JP3566586B2 - Method for measuring powder properties - Google Patents

Description

【００２０】
図５の（２）は、流動状態にある粉体５と振動板６との衝突により生じる振動の、上記設定値以上の周波数帯の強度と設定粒径（本実施形態では７００μｍ）以上の粒子の重量割合である粗粉率との関係の一例を示す。図中〇は粒度分布定数が２．３、図中△は粒度分布定数が３．０、図中□は粒度分布定数が４〜６の場合を示す。これより、その周波数帯の振動強度と粗粉率とは相関し、その粗粉率が大きくなる程に周波数帯の振動強度が大きくなり、しかも、その相関関係に粉体の粒度分布が影響しないことを確認できる。よって、その粗粉率と振動強度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の粗粉率を求めることができる。直線Ｂは、上記信号処理装置１０に記憶される粗粉率と振動強度との予め求めた関係の一例を示す。
【００２１】
図６の（１）は、その粉体５と振動板６との衝突により生じる振動強度の別の一例を示し、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設定値（好ましくは６００Ｈｚ、より好ましくは７００Ｈｚ、さらに好ましくは４００Ｈｚ）以下の周波数帯（本実施形態では７５〜２００Ｈｚ）の振動強度として実効値が求められる。図６の（１）において粉体構成粒子の平均粒径は実線が２８１μｍ、１点鎖線が３７２μｍ、２点鎖線が５０４μｍである。ここでいう振動強度は上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。
【００２２】
図６の（２）は、流動状態にある粉体５と振動板６との衝突により生じる振動の、上記設定値以下の周波数帯の強度と設定粒径（本実施形態では１２５μｍ）以下の粒子の重量割合である微粉率との関係の一例を示す。図中〇は粒度分布定数が２．３、図中△は粒度分布定数が３．０、図中□は粒度分布定数が４〜６の場合を示す。これより、その周波数帯の振動強度と微粉率とは相関し、その微粉率が大きくなる程に周波数帯の振動強度が大きくなり、しかも、その相関関係に粉体５の粒度分布が影響しないことを確認できる。よって、その微粉率と振動強度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の微粉率を求めることができる。直線Ｄは、その信号処理装置１０に記憶される微粉率と振動強度との予め求めた関係の一例を示す。
【００２３】
上記構成によれば、振動強度の測定により粉体５の粗粉率あるいは微粉率を、その粉体５の粒度分布の影響を受けることなく求めることができる。
【００２４】
なお、振動板６に粉体５が付着すると振動強度が変化して測定精度が低下する。そこで、振動板６への粉体５の付着程度が振動強度に与える影響と振動板６の厚さとの関係を求めた。すなわち、振動板６として図４における長さＬが１５０ｍｍ、幅Ｗが７０ｍｍであって、厚さｔが２ｍｍ、３ｍｍ、４ｍｍの場合それぞれについて、同一量の粉体５が付着した時と付着しない時の振動強度を求め、図７の（１）、（２）、（３）に示した。なお、振動板６の自重に対する付着した粉体５の重量割合である付着率は、厚さｔが２ｍｍの場合が２．３％、ｔが３ｍｍの場合が１．５％、ｔが４ｍｍの場合が１．１％である。図７の（１）、（２）、（３）において、実線は粉体５が付着した場合であり、一点鎖線は付着しない場合である。これより、振動板６の厚さが大きい程に粉体５の付着率が小さくなるため、粉体５の付着の影響が小さいことを確認できた。なお、振動板６は重量が大きくなると振動し難くなってＳ／Ｎ比が低下するので、その厚さは適当な値にするのが好ましい。
【００２５】
図８は、振動板６に衝突する粉体５の平均粒子流量と振動強度との関係を示す。その流量が一定であれば問題はないが、変動する場合は流量が低いと振動強度の変動が大きいため、一定以上の流量にするのが好ましい。
【００２６】
図９は、振動板６への粉体５の上下方向における衝突位置と振動強度との関係を示す。その衝突位置は、上下方向中間位置を零とし、上方側を負、下方側を正により表している。なお、振動板６として長さＬが１００ｍｍ、幅Ｗが３５ｍｍであって、厚さｔが２ｍｍのものを使用した。その衝突位置が一定であれば問題はないが、変動する場合は上下方向中間よりも下方であると振動強度の変動が大きいため、上下方向中間よりも上方に衝突させるのが好ましい。
【００２７】
図１０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、粉末洗剤等の製造工程において造粒を行うために粉体を第１、第２造粒装置１１１、１１２内で流動させる。
【００２８】
その第１造粒装置１１１は、横軸心の円筒形状を有する攪拌容器１１１ａと、この容器１１１ａ内で原動機１１１ｂにより横軸１１１ｃ中心に回転駆動されるブレード状の攪拌部材１１１ｄと、その攪拌部材１１１ｄの回転軸１１１ｃの外周部に対向する容器１１１ａの内周部に設けられるブレード状の粉砕部材１１１ｅとを備える。その粉砕部材１１１ｅは粉体の流動領域に位置し、容器１１１ａにより片持ち梁状に支持され、原動機１１１ｆにより容器１１１ａ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１１１ａ内で攪拌部材１１１ｄ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１１１ｅにより粉砕される。また、その容器１１１ａ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１１１ｅとの衝突により生じる振動の強度を検出するセンサ１１４ａが、その粉砕部材１１１ｅの原動機１１１ｆに取り付けられ、そのセンサ１１４ａは信号処理装置１１５に接続される。
【００２９】
その第２造粒装置１１２は、縦軸心の筒形状を有する攪拌容器１１２ａと、この容器１１２ａ内で原動機１１２ｂにより縦軸１１２ｃ中心に回転駆動されるブレード状の攪拌部材１１２ｄと、その攪拌部材１１２ｄの回転軸１１２ｃの外周部に対向する容器１１２ａの内周部に設けられるブレード状の粉砕部材１１２ｅとを備える。その粉砕部材１１２ｅは粉体の流動領域に位置し、容器１１２ａにより片持ち梁状に支持され、原動機１１２ｆにより容器１１２ａ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１１２ａ内で攪拌部材１１２ｄ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１１２ｅにより粉砕される。また、その容器１１２ａ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１１２ｅとの衝突により生じる振動の強度を検出するセンサ１１４ｂが、その粉砕部材１１２ｅの原動機１１２ｆに取り付けられ、そのセンサ１１４ｂは上記信号処理装置１１５に接続される。
【００３０】
その信号処理装置１１５は、第１、第２主増幅器１１５ａ′、１１５ａ″、第１、第２バンドパスフィルター１１５ｂ′、１１５ｂ″、第１、第２補助増幅器１１５ｃ′、１１５ｃ″、第１、第２実効値変換回路１１５ｄ′、１１５ｄ″、第１、第２Ａ／Ｄ変換器１１５ｅ′、１１５ｅ″、および制御装置１１５ｆを有する。
【００３１】
その第１造粒装置１１１のセンサ１１４ａから送られる振動強度の検出信号は、第１の主増幅器１１５ａ′により増幅され、バンドパスフィルター１１５ｂ′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１１５ｃ′により増幅され、実効値変換回路１１５ｄ′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１１５ｅ′によってＡ／Ｄ変換された後に演算装置１１５ｆに入力される。また、第２造粒装置１１２のセンサ１１４ｂから送られる振動強度の検出信号も、第２の主増幅器１１５ａ″、バンドパスフィルター１１５ｂ″、補助増幅器１１５ｃ″、実効値変換回路１１５ｄ″、Ａ／Ｄ変換器１１５ｅ″により、第１造粒装置１１１のセンサ１１４ａから送られる振動強度の検出信号と同様に処理された後に演算装置１１５ｆに入力される。
【００３２】
第１バンドパスフィルター１１５ｂ′を通過する信号の周波数帯は、その粉体と第１造粒装置１１１の粉砕部材１１１ｅ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１１５ｂ″を通過する信号の周波数帯は、その粉体と第２造粒装置１１２の粉砕部材１１２ｅ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粗粉率または微粉率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、粗粉率を求める場合の下限値は例えば７００Ｈｚとされ、微粉率を求める場合の上限値は例えば６００Ｈｚとされる。これにより、粉体と各粉砕部材１１１ｅ、１１２ｅ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。
【００３３】
その制御装置１１５ｆ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１１７、外部記憶装置やプリンター等のデータ記録部１１８、ＣＲＴや液晶ディスプレイ等の表示部１１９が接続される。
【００３４】
その制御装置１１５ｆは、粗粉率を求める場合、第１造粒装置１１１において造粒される粉体の粗粉率と第１バンドパスフィルター１１５ｂ′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１１１において造粒される粉体の目標粗粉率に対応する予め求めた第１バンドパスフィルター１１５ｂ′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１１２において造粒される粉体の目標粗粉率と第２バンドパスフィルター１１５ｂ″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１１２において造粒される粉体の目標粗粉率に対応する予め求めた第２バンドパスフィルター１１５ｂ″を通過する信号の周波数帯の振動強度である第２設定値を記憶する。
また、微粉率を求める場合、その制御装置１１５ｆは、第１造粒装置１１１において造粒される粉体の微粉率と第１バンドパスフィルター１１５ｂ′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１１１において造粒される粉体の目標微粉率に対応する予め求めた第１バンドパスフィルター１１５ｂ′を通過する信号の周波数帯の振動強度である第３設定値、第２造粒装置１１２において造粒される粉体の目標微粉率と第２バンドパスフィルター１１５ｂ″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１１２において造粒される粉体の目標微粉率に対応する予め求めた第２バンドパスフィルター１１５ｂ″を通過する信号の周波数帯の振動強度である第４設定値を記憶する。
【００３５】
そして制御装置１１５ｆは、その第１造粒装置１１１において検出された上記各周波数帯の振動強度に対応する粗粉率または微粉率と、第２造粒装置１１２において検出された上記各周波数帯の振動強度に対応する粗粉率または微粉率とを、上記各記憶した関係に基づき演算し、その演算結果をデータ記録部１１８や表示部１１９に出力する。
【００３６】
また、その制御装置１１５ｆは、その第１造粒装置１１１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、または、その第１造粒装置１１１において検出された上記周波数帯の振動強度が第３設定値である時は、第１造粒装置１１１の各原動機１１１ｂ、１１１ｆを停止させる制御信号を出力し、第１造粒装置１１１による造粒を終了させ、その第２造粒装置１１２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、または、その第２造粒装置１１１において検出された上記周波数帯の振動強度が第４設定値である時は、第２造粒装置１１２の各原動機１１２ｂ、１１２ｆを停止させる制御信号を出力し、第２造粒装置１１２による造粒を終了させる。上記周波数帯の振動強度と粗粉率との関係、および上記周波数帯の振動強度と微粉率との関係は、粉体の粒度分布の影響を受けないので、この構成によれば、造粒過程で粉体の粒度分布が変化しても造粒終点を精度良く求めることが可能になる。
【００３７】
図１１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。
第３実施形態は第２実施形態と信号処理装置を除いて同様の構成を有する。その第３実施形態の信号処理装置１１５′は、第２実施形態の信号処理装置１１５と制御装置を除いては同様とされ、第１造粒装置１１１における粉体と粉砕部材１１１ｅ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１１２における粉体と粉砕部材１１２ｅ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を、それぞれ時系列に検出する。
【００３８】
第３実施形態の信号処理装置１１５′の制御装置１１５ｆ′は、粗粉率を求める場合、第１造粒装置１１１における造粒開始からの経過時間と粉体の基準粗粉率に対応する第１バンドパスフィルター１１５ｂ′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、および、第２造粒装置１１２における造粒開始からの経過時間と粉体の基準粗粉率に対応する第２バンドパスフィルター１１５ｂ″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。
また、微粉率を求める場合、その制御装置１１５ｆ′は、第１造粒装置１１１における造粒開始からの経過時間と粉体の基準微粉率に対応する第１バンドパスフィルター１１５ｂ′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３の関係、および、第２造粒装置１１２における造粒開始からの経過時間と粉体の基準微粉率に対応する第２バンドパスフィルター１１５ｂ″を通過する周波数帯の振動強度との予め定めた第４の関係を記憶する。
各基準粗粉率および各基準微粉率は、その予め定めた経過時間と周波数帯の強度との関係が満たされる時、その時点での粉体の粗粉率または微粉率の目標値として設定される値であって、任意の値に設定できる。
【００３９】
粗粉率を求める場合、その制御装置１１５ｆ′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１１１において検出した上記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粗粉率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１１１の造粒条件を変更し、また、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１１２において検出した上記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粗粉率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１１２の造粒条件を変更する。
【００４０】
微粉率を求める場合、その制御装置１１５ｆ′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１１１において検出した上記周波数帯の振動強度を、上記第３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微粉率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１１１の造粒条件を変更し、また、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１１２において検出した上記周波数帯の振動強度を、上記第４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微粉率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１１２の造粒条件を変更する。
【００４１】
なお、各検出した周波数帯の振動強度と基準粗粉率または微粉率に対応する周波数帯の振動強度との差と、第１造粒装置１１１または第２造粒装置１１２の造粒条件の変更量との関係は、予め定められて制御装置１１５ｆ′に記憶される。
【００４２】
バッチプロセスにより造粒を行う場合、各造粒装置１１１、１１２の攪拌部材１１１ｄ、１１２ｄや粉砕部材１１１ｅ、１１２ｅ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１１１ｂ、１１１ｆ、１１２ｂ、１１２ｆ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１１１ａ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１２５に送ることで造粒条件を変更できる。
例えば、造粒開始から任意時間の経過時間において、検出された周波数帯の振動強度が基準粗粉率に対応する周波数帯の振動強度よりも小さい場合や、検出された周波数帯の振動強度が基準微粉率に対応する周波数帯の振動強度よりも大きい場合、造粒を促進する必要があることから、その差に応じて予め設定されて記憶された量だけ、攪拌部材１１１ｄ、１１２ｄや粉砕部材１１１ｅ、１１２ｅの回転速度を増速したり、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。
また、造粒開始から任意時間の経過時間において、検出された周波数帯の振動強度が基準粗粉率に対応する周波数帯の振動強度よりも大きい場合や、検出された周波数帯の振動強度が基準微粉率に対応する周波数帯の振動強度よりも小さい場合、造粒を抑制する必要があることから、その差に応じて予め設定されて記憶された量だけ、攪拌部材１１１ｄ、１１２ｄや粉砕部材１１１ｅ、１１２ｅの回転速度を減速したり、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。
これにより、造粒過程で粉体の粒度分布が変化しても、粉体の粗粉率または微粉率を任意の目標値に精度良く近付けることができる。他は第２実施形態と同様とされている。
【００４３】
なお、上記各実施形態では粗粉率と微粉率の中の一方を測定したが、粗粉率を求めるための信号処理装置と微粉率を求めるための信号処理装置の双方を設けることで、両方を同時に測定するようにしてもよい。なお、造粒制御において粗粉率と微粉率の両方を求める場合において、粗粉率による制御量と微粉率による制御量とが一致しない場合は、何れを優先させるか予め定めておけばよい。また、第２、第３実施形態を組み合わせ、造粒終点の制御と、造粒条件の制御を同時に行うようにしてもよい。また、第２、第３実施形態における粉砕部材１１１ｅ、１１２ｅに代えて、第１実施形態に示す振動板６を、各造粒装置１１１、１１２に設け振動強度を検出してもよい。
【００４４】
【発明の効果】
本発明によれば、粉体の粒度分布の影響を受けることのない粉体性状として粗粉率および微粉率を精度良く求めることができる測定方法と、造粒の終点を精度良く求めることができ、造粒時において粗粉率や微粉率を所望の値に精度良く近付けて品質管理に寄与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】（１）、（２）、（３）は粒度分布定数が互いに異なる粉体の粒度分布を示す図
【図２】粉体構成粒子の平均粒径と予め定めた周波数帯における振動強度と粒度分布定数との関係を示す図
【図３】本発明の第１実施形態における粉体性状の測定方法を実施するための構成説明図
【図４】本発明の第１実施形態における粉体性状の測定方法を実施するための要部の構成説明図
【図５】本発明の第１実施形態における（１）は予め定めた周波数帯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粗粉率との関係を示す図
【図６】本発明の第１実施形態における（１）は予め定めた周波数帯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微粉率との関係を示す図
【図７】（１）、（２）、（３）はそれぞれ、本発明の第１実施形態における振動板の厚さが互いに異なる場合の振動スペクトルを示す図
【図８】本発明の第１実施形態における粉体流量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９】本発明の第１実施形態における振動板への粉体衝突位置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１０】本発明の第２実施形態における造粒制御を実施するための構成説明図
【図１１】本発明の第３実施形態における造粒制御を実施するための構成説明図
【符号の説明】
１ 測定装置
５ 粉体
６ 振動板
８ センサ
１０ 信号処理装置
１１１ 第１造粒装置
１１１ｅ 粉砕部材
１１２ 第２造粒装置
１１２ｅ 粉砕部材
１１４ａ センサ
１１４ｂ センサ
１１５ 信号処理装置
１１５′ 信号処理装置[0001]
TECHNICAL FIELD OF THE INVENTION
In the present invention, as a property of a powder in a fluidized state, a coarse powder ratio which is a weight ratio of particles having a set particle size or more in the powder and a fine powder ratio which is a weight ratio of particles having a set particle size or less are measured. The present invention relates to a method and a method for controlling granulation performed by flowing powder.
[0002]
[Prior art]
In the production process of pharmaceuticals, agricultural chemicals, detergents, and the like, it is necessary to measure the properties of powder in a fluid state. For example, a granulation end point control device disclosed in Japanese Patent Application Laid-Open No. 63-232831 is provided in a stirring vessel when powder is caused to flow by a stirring rotor in a stirring vessel in order to perform granulation. By detecting the collision pressure of the powder on the probe, converting the collision pressure into an electric signal and performing a fast Fourier transform, the characteristic frequency corresponding to the product of the rotation speed of the stirring rotor and the number of stirring blades is obtained. Find the vibration intensity of Since the vibration intensity corresponds to the particle size of the powder constituent particles, the granulation is terminated when the vibration intensity reaches a predetermined value, whereby a powder having a desired particle size can be obtained.
[0003]
Further, the method for detecting a granulation state disclosed in Japanese Patent Application Laid-Open No. Hei 5-237357 discloses a method for detecting the vibration intensity of a container when a powder is flowed by an impeller in a stirring container to perform granulation, and the condition in which the container is empty. Then, the vibration intensity of the container when the impeller is driven is obtained, and the frequency for clearly discriminating the two is defined as the specific frequency. Focusing on the correlation between the vibration intensity at the specific frequency and the bulk density of the powder, the granulation state is detected according to the bulk density corresponding to the vibration intensity.
[0004]
[Problems to be solved by the invention]
In the first prior art, the characteristic frequency is the product of the number of rotations of the stirring rotor and the number of the stirring blades. Therefore, the vibration intensity at the characteristic frequency is accompanied by the stirring blade passing near the probe. Corresponding to the collision pressure between the particles and the probe. Therefore, the above-mentioned conventional technology is applicable only when the particle flow rate colliding with the probe periodically fluctuates due to the stirring blade, and cannot be applied when the particle flow rate is constant and lacks versatility. There's a problem. Further, the characteristic frequency is a relatively low frequency of about several tens of Hz because it is a product of the number of rotations of the stirring rotor and the number of stirring blades, and is therefore based on vibrations of other devices existing around. The influence of noise is large, and the granulation end point cannot be obtained with high accuracy.
[0005]
In the second conventional technique, the specific frequency is a relatively low frequency of about several tens of Hz, and therefore, the influence of noise due to vibrations of other devices existing in the surroundings is large, and the granulation state cannot be detected with high accuracy. . Further, since the vibration intensity at the specific frequency is based on the correlation with the bulk density of the powder, when the powder constituent particles include, for example, a substance that causes a chemical reaction or the like during granulation, the The surface properties and the like of the particles change due to a chemical reaction or the like, and the bulk density fluctuates. Then, the vibration intensity does not correlate with the bulk density of the powder, and the granulation state cannot be detected.
[0006]
Therefore, the average particle size is measured from the vibration intensity based on the correlation between the average particle size of the powder constituent particles and the vibration intensity in a predetermined frequency band including the natural frequency of the portion located in the powder flow region. However, it is conceivable to use it for granulation control.However, when the particle size distribution of the powder in the granulation process, that is, the weight ratio of the respective powder constituent particles having different particle sizes in the powder changes, the frequency band of the The correlation between the vibration intensity and the average particle diameter is weakened, and the measurement accuracy is reduced. For example, FIG. 1 (1) shows a powder having a particle size distribution constant of 2.3, FIG. 1 (2) shows a particle size distribution constant of 3.0, and FIG. Shows the particle size distribution of the body, the horizontal axis is the particle size, the vertical axis is the weight ratio of the powder constituting particles of each particle size in the powder, using a plurality of stacked sieves having different aperture sizes from each other It was determined by dividing the powder. In (1) of FIG. 1, the average particle diameter of the particles constituting the powder is 274 μm in the solid line, 351 μm in the one-dot chain line, and 438 μm in the two-dot chain line. The average particle diameter of the particles constituting the powder is 287 μm, the solid line is 387 μm, the two-dot chain line is 526 μm. The particle size distribution constant is obtained from the Rosin-Rammler equation. As this constant is larger, the weight ratio of particles of any particle size in the powder is intensively increased. FIG. 2 is an example showing the relationship between the vibration intensity in the frequency band and the average particle size of the particles constituting the powder. In FIG. 2, 〇 indicates a particle size distribution constant of 2.3, and △ indicates a particle size distribution constant of 3. 0, □ in the figure indicate the case where the particle size distribution constant is 4 to 6. If the particle size distribution is constant, the average particle size is substantially proportional to the vibration intensity. The correlation becomes weak, and it becomes impossible to accurately determine the average particle size from the vibration intensity.
[0007]
In view of the above circumstances, an object of the present invention is to provide a method for measuring powder properties that can be used for granulation end point detection and granulation control without being affected by the particle size distribution.
[0008]
[Means for Solving the Problems]
A first characteristic of the powder property measuring method of the present invention is that a predetermined set value including a natural frequency of a vibration generated by a collision between the powder and a portion located in a flow region of the powder in a flowing state. Detecting the intensity of the above frequency band, based on a previously determined relationship between the coarse powder ratio and the vibration intensity of the frequency band, which is a weight ratio of particles having a set particle size or more in the powder, based on the detected frequency band. The point is to determine the coarse powder ratio corresponding to the vibration intensity.
The second feature of the powder property measuring method of the present invention is that a predetermined set value including a natural frequency of a vibration generated by a collision between the powder and a portion located in a flow region of the powder in a flowing state. Detecting the intensity of the following frequency band, based on a relationship previously determined between the fine powder ratio, which is a weight ratio of particles having a particle size equal to or less than the set particle size, and the vibration intensity of the frequency band, the vibration of the detected frequency band. The point is to determine the fine powder ratio corresponding to the strength.
In the present invention, the intensity of the frequency band including the natural frequency of the vibration generated by the collision between the powder and the portion located in the flow region of the powder in the flowing state is correlated with the coarse powder ratio in the frequency band above a certain level. However, it is correlated with the fine powder ratio in a frequency band below a certain level, and the correlation is based on the finding that the correlation is not affected by the particle size distribution of the powder. Thus, the coarse powder ratio and the fine powder ratio of the powder can be obtained by measuring the vibration intensity in each frequency band without being affected by the particle size distribution of the powder.
[0009]
When determining the coarse powder ratio, the lower limit of the set particle size for specifying the coarse powder and the lower limit of the frequency band for measuring the vibration intensity are set so that the correlation between the vibration intensity and the coarse powder ratio becomes strong. Is preferred. When determining the fine powder ratio, the upper limit of the set particle size for specifying the fine powder and the upper limit of the frequency band for measuring the vibration intensity are set so that the correlation between the vibration intensity and the fine powder ratio becomes strong. Is preferred.
[0010]
The first feature of the granulation control method of the present invention is that, when the powder is flowed to perform granulation, at least one of the measurement of the coarse powder ratio and the measurement of the fine powder ratio by the method of the present invention is performed. When at least one of the measured coarse powder ratio and fine powder ratio is a predetermined set value, the granulation is terminated.
The relationship between the vibration intensity in the frequency band and the coarse powder ratio, and the relationship between the vibration intensity in the frequency band and the fine powder ratio are not affected by the particle size distribution of the powder. Thus, even if the particle size distribution of the powder changes, the granulation end point can be obtained with high accuracy. Thereby, the coarse powder ratio or the fine powder ratio of the powder can be set to a predetermined value required in a processing step such as powder crushing after granulation.
[0011]
The second feature of the granulation control method of the present invention is that, when the powder is flowed to perform granulation, at least one of the measurement of the coarse powder ratio and the measurement of the fine powder ratio according to the method of the present invention is performed. , Comparison of the predetermined relationship between the elapsed time from the start of granulation and the reference coarse powder ratio and the coarse powder ratio measured at an arbitrary time after the start of granulation, and the elapsed time from the start of granulation Perform at least one of the predetermined relationship between the reference fine powder ratio of the powder and the comparison of the fine powder ratio measured at an arbitrary time after the start of granulation, and the measured coarse powder ratio and the reference coarse powder ratio. The point is to change the granulation conditions so as to reduce at least one of the difference between the fine powder ratio and the difference between the fine powder ratio and the reference fine powder ratio.
Difference between the coarse powder ratio determined from the vibration intensity of the frequency band detected at the elapse of an arbitrary time from the start of granulation and a predetermined reference coarse powder ratio, or the fine powder ratio determined from the vibration intensity of the frequency band. By changing the granulation conditions so as to reduce the difference from the predetermined reference fine powder rate, the influence of the particle size distribution of the powder is small, and the coarse powder rate or the fine powder rate of the powder can be set to an arbitrary target value. Can be accurately approached.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
The measuring device 1 shown in FIG. 3 conveys the powder 5 fed into the hopper 2 by the electromagnetic feeder 3 controlled by the control device 10e, throws the powder 5 into the chute 4, and falls from the chute 4 so that the powder 5 flows. Is measured, and the bulk density is further measured. A diaphragm 6 is arranged in the flow region of the powder 5 for measuring the coarse powder ratio and the fine powder ratio. As shown in FIG. 4, the diaphragm 6 is supported in a cantilever shape by a support member 7 attached to the fixed side. A sensor 8 such as an acceleration sensor for detecting the intensity of vibration generated by the collision between the powder 5 and the vibration plate 6 in time series is attached to the vibration plate 6, and the sensor 8 is connected to the signal processing device 10. .
[0013]
The signal processing device 10 includes a main amplifier 10a, a filter circuit 10b, an auxiliary amplification and effective value detection circuit 10c, an average value calculation and scaling circuit 10d, and a control device 10e.
[0014]
The detection signal of the vibration intensity sent from the sensor 8 is amplified by the main amplifier 10a, a signal in a frequency band other than a predetermined frequency band is removed by the filter circuit 10b, and amplified by the auxiliary amplification and effective value detection circuit 10c. Is converted into a DC voltage signal having a value corresponding to an effective value corresponding to the intensity of the frequency band. This DC voltage signal is integrated during the set time period by the average value calculation and scaling circuit 10d that receives a trigger signal output from the control device 10e at the timing of starting the electromagnetic feeder 3. The average value calculation and scaling circuit 10d obtains the average vibration intensity by dividing the integrated value by the integration time, and calculates the coarse powder ratio and the fine powder ratio corresponding to the average vibration intensity by dividing the coarse powder ratio and the frequency band. A signal Sa corresponding to the determined coarse powder ratio or fine powder ratio is determined based on a relationship previously determined with the vibration intensity and a previously determined relationship between the fine powder ratio and the vibration intensity in the frequency band. And so on.
[0015]
The frequency band of the signal passing through the filter circuit 10b is determined so as to include the natural frequency of the vibration generated by the collision between the powder and the vibration plate 6, and the specific value is the coarse powder ratio or the fine powder ratio. It can be predetermined by experiment so that it can be obtained with desired accuracy. As a result, the intensity of the vibration generated by the collision between the powder and the diaphragm 6 in the predetermined frequency band including the natural frequency is detected.
[0016]
The control device 10e outputs a trigger signal to the control circuit 13 of the electromagnetic valve 12 provided in the middle of the compressed air conveying pipe 11 at the timing when the electromagnetic feeder 3 is stopped. Air is blown from the nozzle 11a to the diaphragm 6 to prevent powder constituent particles from adhering to the diaphragm 6.
[0017]
A bulk density measuring container 21 is arranged at a position for receiving the powder 5 falling after vibrating the vibrating plate 6. The powder 5 stored in the container 21 is slid off by a slicing plate 23 attached to an air cylinder 22b reciprocally driven by a pneumatic device 22a controlled by a control device 10e. The weight is measured, and this measurement signal is output to the control device 10e. The control device 10e calculates the bulk density of the powder 5 from the measured weight of the powder 5, the container 21, and the known weight and volume of the container 21, and outputs a signal Sb corresponding to the determined bulk density to a printer. Output to device, personal computer, etc. Thereby, the bulk density can be determined while continuously measuring the coarse powder ratio or the fine powder ratio of the powder 5. When the container 21 is inverted by the actuator 25 controlled by the control device 10e, the powder 5 is discharged from the container 21 and collected. The measurement area of the coarse powder ratio, the fine powder ratio, and the bulk density of the powder 5 is covered with the cover 29. The weight measurement of the powder 5 and the container 21 by the load cell 24 is detected based on the bending of the output shaft 25a of the actuator 25 that rotates the container 21.
[0018]
FIG. 5A shows an example of the vibration intensity generated by the collision between the powder 5 and the diaphragm 6, and in the present embodiment, a predetermined set value including a natural frequency in a range indicated by A in the figure (FIG. 5A). The effective value is obtained as a vibration intensity in a frequency band (preferably 700 Hz, more preferably 1000 Hz, and still more preferably 1500 Hz) or higher (in the present embodiment, 6350 to 6700 Hz). In (1) of FIG. 5, the average particle diameter of the particles constituting the powder is 281 μm for the solid line, 372 μm for the one-dot chain line, and 504 μm for the two-dot chain line. Here, the vibration intensity is calculated by calculating the effective value of the AC signal according to the following equation, but the vibration intensity may be calculated using a time average of the absolute value of the AC signal.
[0019]
(Equation 1)

[0020]
FIG. 5 (2) shows the intensity of the frequency band and the particle size (700 μm in the present embodiment) or more of the frequency band equal to or higher than the set value of the vibration generated by the collision between the powder 5 and the vibration plate 6 in the flowing state. An example of a relationship with the coarse powder ratio, which is the weight ratio of the powder, is shown. In the figure, 〇 indicates a case where the particle size distribution constant is 2.3, △ indicates a case where the particle size distribution constant is 3.0, and □ indicates a case where the particle size distribution constant is 4 to 6. Thus, the vibration intensity in the frequency band is correlated with the coarse powder ratio, and the higher the coarse powder ratio, the greater the vibration intensity in the frequency band, and furthermore, the particle size distribution of the powder does not affect the correlation. You can confirm that. Therefore, from the stored relationship between the coarse powder ratio and the vibration intensity, the coarse powder ratio of the powder corresponding to the detected value of the vibration intensity can be obtained. A straight line B indicates an example of a previously determined relationship between the coarse powder ratio and the vibration intensity stored in the signal processing device 10.
[0021]
FIG. 6A shows another example of the vibration intensity generated by the collision between the powder 5 and the diaphragm 6, and in this embodiment, a predetermined setting including a natural frequency in a range indicated by C in the drawing. The effective value is obtained as the vibration intensity in a frequency band (preferably 600 Hz, more preferably 700 Hz, and still more preferably 400 Hz) or less (75 to 200 Hz in the present embodiment). In (1) of FIG. 6, the average particle diameter of the powder constituent particles is 281 μm for the solid line, 372 μm for the one-dot chain line, and 504 μm for the two-dot chain line. Here, the vibration intensity is calculated by calculating the effective value of the AC signal according to the above equation, but the vibration intensity may be calculated using a time average of the absolute value of the AC signal.
[0022]
FIG. 6 (2) shows the intensity of the frequency band below the above set value and the particle size below the set particle size (125 μm in this embodiment) of the vibration generated by the collision between the powder 5 and the diaphragm 6 in the flowing state. An example of the relationship with the fine powder ratio, which is the weight ratio of, is shown. In the figure, 〇 indicates a case where the particle size distribution constant is 2.3, △ indicates a case where the particle size distribution constant is 3.0, and □ indicates a case where the particle size distribution constant is 4 to 6. Thus, the vibration intensity in the frequency band and the fine powder ratio are correlated, and the higher the fine powder ratio, the greater the vibration intensity in the frequency band, and the particle size distribution of the powder 5 does not affect the correlation. Can be confirmed. Therefore, from the stored relationship between the fine powder ratio and the vibration intensity, the fine powder ratio of the powder corresponding to the detected value of the vibration intensity can be obtained. A straight line D indicates an example of a relationship between the fine powder ratio and the vibration intensity stored in the signal processing device 10 in advance.
[0023]
According to the above configuration, the coarse powder ratio or the fine powder ratio of the powder 5 can be obtained by measuring the vibration intensity without being affected by the particle size distribution of the powder 5.
[0024]
When the powder 5 adheres to the vibration plate 6, the vibration intensity changes and the measurement accuracy decreases. Therefore, the relationship between the effect of the degree of adhesion of the powder 5 to the diaphragm 6 on the vibration strength and the thickness of the diaphragm 6 was determined. That is, when the length L in FIG. 4 is 150 mm, the width W is 70 mm, and the thickness t is 2 mm, 3 mm, and 4 mm in FIG. The vibration intensity at the time was obtained and shown in (1), (2) and (3) of FIG. The adhesion ratio, which is the weight ratio of the powder 5 adhered to the weight of the diaphragm 6, is 2.3% when the thickness t is 2 mm, 1.5% when the thickness t is 3 mm, and 4% when the thickness t is 4 mm. The case is 1.1%. In (1), (2), and (3) of FIG. 7, the solid line indicates the case where the powder 5 is attached, and the dashed line indicates the case where the powder 5 is not attached. From this, it was confirmed that the effect of the adhesion of the powder 5 was small because the larger the thickness of the diaphragm 6 was, the smaller the adhesion ratio of the powder 5 was. It is preferable that the thickness of the diaphragm 6 be set to an appropriate value because the vibration plate 6 becomes hard to vibrate and the S / N ratio decreases when the weight increases.
[0025]
FIG. 8 shows the relationship between the average particle flow rate of the powder 5 colliding with the diaphragm 6 and the vibration intensity. If the flow rate is constant, there is no problem. However, if the flow rate fluctuates, if the flow rate is low, the fluctuation of the vibration intensity is large.
[0026]
FIG. 9 shows the relationship between the impact position of the powder 5 on the diaphragm 6 in the vertical direction and the vibration intensity. The collision position is represented by zero at the middle position in the vertical direction, negative on the upper side, and positive on the lower side. Note that the diaphragm 6 used had a length L of 100 mm, a width W of 35 mm, and a thickness t of 2 mm. There is no problem if the collision position is constant, but if it fluctuates, it is preferable to make the collision higher than the middle in the up-down direction because the fluctuation of the vibration intensity is large below the middle in the up-down direction.
[0027]
A second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, powder is made to flow in the first and second granulating devices 111 and 112 in order to perform granulation in a manufacturing process of a powder detergent or the like.
[0028]
The first granulator 111 includes a stirring vessel 111a having a cylindrical shape with a horizontal axis, a blade-shaped stirring member 111d that is driven to rotate about a horizontal axis 111c by a motor 111b in the vessel 111a, And a blade-like crushing member 111e provided on the inner periphery of the container 111a facing the outer periphery of the rotation shaft 111c of the rotation shaft 111d. The pulverizing member 111e is located in the flow region of the powder, is supported in a cantilever shape by the container 111a, and is rotationally driven by the motor 111f about the axis along the radial direction of the container 111a. The powder is fluidized by being stirred by the stirring member 111d in the container 111a, and is crushed by the crushing member 111e. In addition, a granulating liquid for granulating the powder, a reaction liquid that causes a chemical reaction upon contact with the powder, and the like are supplied into the container 111a from a pipe (not shown). A sensor 114a for detecting the intensity of vibration generated by the collision between the powder and the crushing member 111e is attached to a motor 111f of the crushing member 111e, and the sensor 114a is connected to the signal processing device 115.
[0029]
The second granulator 112 includes a stirring vessel 112a having a cylindrical shape with a vertical axis, a blade-like stirring member 112d that is driven to rotate about a vertical axis 112c by a motor 112b in the vessel 112a, A blade-like crushing member 112e provided on the inner periphery of the container 112a facing the outer periphery of the rotation shaft 112c of the 112d. The pulverizing member 112e is located in the flow region of the powder, is supported in a cantilever shape by the container 112a, and is rotationally driven by the motor 112f about an axial center along the radial direction of the container 112a. The powder flows while being stirred by the stirring member 112d in the container 112a, and is pulverized by the pulverizing member 112e. In addition, a granulating liquid for granulating the powder, a reaction liquid that causes a chemical reaction upon contact with the powder, and the like are supplied into the container 112a from a pipe (not shown). A sensor 114b for detecting the intensity of vibration generated by the collision between the powder and the crushing member 112e is attached to a motor 112f of the crushing member 112e, and the sensor 114b is connected to the signal processing device 115.
[0030]
The signal processing device 115 includes first and second main amplifiers 115a ′ and 115a ″, first and second bandpass filters 115b ′ and 115b ″, first and second auxiliary amplifiers 115c ′ and 115c ″, first and second It has second effective value conversion circuits 115d 'and 115d ", first and second A / D converters 115e' and 115e", and a control device 115f.
[0031]
The detection signal of the vibration intensity sent from the sensor 114a of the first granulator 111 is amplified by a first main amplifier 115a ', and a signal other than a predetermined frequency band is removed by a band-pass filter 115b'. After being amplified by an amplifier 115c ', converted by an effective value conversion circuit 115d' into a DC signal having a value corresponding to an effective value corresponding to the intensity of the frequency band, and subjected to A / D conversion by an A / D converter 115e ', It is input to the arithmetic unit 115f. Further, the detection signal of the vibration intensity sent from the sensor 114b of the second granulator 112 also includes the second main amplifier 115a ″, the band-pass filter 115b ″, the auxiliary amplifier 115c ″, the effective value conversion circuit 115d ″, and the A / D After being processed in the same manner as the vibration intensity detection signal sent from the sensor 114a of the first granulating device 111 by the converter 115e ″, it is input to the arithmetic device 115f.
[0032]
The frequency band of the signal passing through the first band-pass filter 115b 'is determined to include the natural frequency of the vibration generated by the collision between the powder and the pulverizing member 111e of the first granulating device 111, and the second band The frequency band of the signal passing through the pass filter 115b ″ is determined so as to include the natural frequency of the vibration generated by the collision between the powder and the pulverizing member 112e of the second granulator 112, and the specific value Can be determined by an experiment so that the coarse powder ratio or the fine powder ratio can be obtained with a desired accuracy, the lower limit value for obtaining the coarse powder ratio is, for example, 700 Hz, and the upper limit value for obtaining the fine powder ratio is, for example, Accordingly, the intensity of a predetermined frequency band including a natural frequency of each of the vibrations caused by the collision between the powder and each of the crushing members 111e and 112e is set to 600 Hz. It is detected.
[0033]
The control device 115f is configured by a computer, and is connected to an input device 117 such as a keyboard, a data recording unit 118 such as an external storage device or a printer, and a display unit 119 such as a CRT or a liquid crystal display.
[0034]
When calculating the coarse powder ratio, the control device 115f compares the coarse powder ratio of the powder granulated in the first granulating device 111 with the vibration intensity of the frequency band of the signal passing through the first band-pass filter 115b '. A predetermined relationship, which is the vibration intensity in the frequency band of the signal passing through the first band-pass filter 115b ', which is obtained in advance and corresponds to the target coarseness ratio of the powder to be granulated in the first granulator 111, 1, a predetermined relationship between the target coarse powder ratio of the powder to be granulated in the second granulator 112 and the vibration intensity in the frequency band of the signal passing through the second band-pass filter 115b ″; The second set value, which is the vibration intensity of the frequency band of the signal passing through the second band-pass filter 115b ″ corresponding to the target coarse powder ratio of the powder to be granulated in the second granulator 112, is stored.
When determining the fine powder ratio, the control device 115f calculates the difference between the fine powder ratio of the powder granulated by the first granulating device 111 and the vibration intensity of the frequency band of the signal passing through the first band-pass filter 115b '. A third relationship, which is a predetermined relationship, the vibration intensity in the frequency band of the signal passing through the first band-pass filter 115b ', which is obtained in advance and corresponds to the target fineness ratio of the powder to be granulated in the first granulator 111. A predetermined relationship between the set value, the target fineness ratio of the powder granulated by the second granulator 112 and the vibration intensity of the frequency band of the signal passing through the second band-pass filter 115b ″, and the second granulation A fourth set value which is a vibration intensity in a frequency band of a signal passing through the second band-pass filter 115b ″ corresponding to a target fineness ratio of the powder to be granulated in the granulation device 112 is stored. .
[0035]
Then, the control device 115f controls the coarse powder ratio or the fine powder ratio corresponding to the vibration intensity of each of the frequency bands detected by the first granulating device 111 and the frequency of the respective frequency bands detected by the second granulating device 112. A coarse powder ratio or a fine powder ratio corresponding to the vibration intensity is calculated based on the stored relationships, and the calculation result is output to the data recording unit 118 and the display unit 119.
[0036]
Further, the control device 115f is configured to control whether the vibration intensity of the frequency band detected by the first granulating device 111 is a first set value or the frequency band detected by the first granulating device 111. When the vibration intensity of the first granulator 111 is the third set value, a control signal for stopping each of the motors 111b and 111f of the first granulator 111 is output, and the granulation by the first granulator 111 is terminated. When the vibration intensity of the frequency band detected by the granulator 112 is the second set value, or when the vibration intensity of the frequency band detected by the second granulator 111 is the fourth set value Outputs a control signal for stopping each of the prime movers 112b and 112f of the second granulator 112, and terminates granulation by the second granulator 112. The relationship between the vibration intensity in the frequency band and the coarse powder ratio and the relationship between the vibration intensity in the frequency band and the fine powder ratio are not affected by the particle size distribution of the powder. Thus, even if the particle size distribution of the powder changes, the granulation end point can be obtained with high accuracy.
[0037]
A third embodiment of the present invention will be described with reference to FIG. The same parts as those in the second embodiment are denoted by the same reference numerals.
The third embodiment has the same configuration as the second embodiment except for the signal processing device. The signal processing device 115 'of the third embodiment is the same as the signal processing device 115 of the second embodiment except for the control device, and the collision between the powder in the first granulating device 111 and the crushing member 111e is performed. The intensity of a predetermined frequency band including the natural frequency of the generated vibration, and the intensity of the predetermined frequency band including the natural frequency of the vibration generated by the collision between the powder and the crushing member 112e in the second granulating device 112. Are detected in time series.
[0038]
When determining the coarse powder ratio, the control device 115f 'of the signal processing device 115' of the third embodiment determines the elapsed time from the start of granulation in the first granulating device 111 and the reference coarse powder ratio of the powder. The first predetermined relationship with the vibration intensity in the frequency band of the signal passing through the one band-pass filter 115b ', the elapsed time from the start of granulation in the second granulator 112, and the reference coarse powder ratio And a second predetermined relationship with the vibration intensity of the frequency band passing through the second band-pass filter 115b ″ corresponding to.
When obtaining the fine powder ratio, the control device 115f 'controls the signal passing through the first band-pass filter 115b' corresponding to the elapsed time from the start of granulation in the first granulator 111 and the reference fine powder ratio. And the second band-pass filter 115b ″ corresponding to the predetermined relationship with the vibration intensity in the frequency band of the second, the elapsed time from the start of granulation in the second granulator 112, and the reference fineness ratio of the powder. A fourth relationship that is predetermined with the vibration intensity of the passing frequency band is stored.
Each reference coarse powder rate and each reference fine powder rate are set as target values of the coarse powder rate or the fine powder rate at that time when the relationship between the predetermined elapsed time and the intensity of the frequency band is satisfied. And can be set to any value.
[0039]
When calculating the coarse powder ratio, the control device 115f 'compares the vibration intensity of the frequency band detected by the first granulating device 111 with the first relationship at the time when an arbitrary time has elapsed from the start of granulation. Find the difference between the detected vibration intensity of the frequency band and the vibration intensity of the frequency band corresponding to the reference coarse powder ratio, change the granulation conditions of the first granulator 111 to reduce the difference, and At an elapse of an arbitrary time from the start of granulation, the vibration intensity of the frequency band detected by the second granulator 112 is compared with the second relationship, and the vibration intensity of the detected frequency band and the reference coarse powder are compared. The difference from the vibration intensity in the frequency band corresponding to the rate is determined, and the granulation conditions of the second granulator 112 are changed so as to reduce the difference.
[0040]
When determining the fine powder ratio, the control device 115f 'compares the vibration intensity of the frequency band detected by the first granulation device 111 with the third relationship at the time when an arbitrary time has elapsed from the start of granulation, The difference between the detected vibration intensity in the frequency band and the vibration intensity in the frequency band corresponding to the reference fine powder ratio is obtained, and the granulation conditions of the first granulator 111 are changed so as to reduce the difference. At an elapse of an arbitrary time from the start of the granulation, the vibration intensity of the frequency band detected by the second granulator 112 is compared with the fourth relation, and the vibration intensity of the detected frequency band and the reference fine powder rate are corresponded. The difference between the frequency and the vibration intensity of the frequency band to be obtained is obtained, and the granulation conditions of the second granulator 112 are changed so as to reduce the difference.
[0041]
In addition, the difference between the vibration intensity of each detected frequency band and the vibration intensity of the frequency band corresponding to the reference coarse powder ratio or the fine powder ratio, and the change of the granulation conditions of the first granulator 111 or the second granulator 112. The relationship with the quantity is predetermined and stored in the control device 115f '.
[0042]
When performing granulation by a batch process, the rotational speeds of the stirring members 111d and 112d and the crushing members 111e and 112e of each of the granulators 111 and 112 can be set as granulation conditions to be changed. For example, the prime movers 111b and 111f , 112b, 112f can change the granulation conditions. When granulation is performed by a continuous process, the residence time of the powder can be used as the granulation condition. For example, the opening control signal of the gate valve for taking out the powder from the stirring vessel 111a is transmitted to the gate valve driving device 125. The granulation conditions can be changed by sending to
For example, when the vibration intensity of the detected frequency band is smaller than the vibration intensity of the frequency band corresponding to the reference coarse powder ratio, or the vibration intensity of the detected frequency band When the vibration intensity is higher than the vibration intensity in the frequency band corresponding to the fine powder ratio, it is necessary to promote the granulation. Therefore, the stirring members 111d and 112d and the crushing member 111e are stored in an amount preset and stored according to the difference. , 112e in order to increase the rotation speed and to prolong the residence time of the powder, the opening of the gate valve for powder removal is reduced.
In addition, when the vibration intensity of the detected frequency band is greater than the vibration intensity of the frequency band corresponding to the reference coarse powder ratio during the lapse of an arbitrary time from the start of granulation, or when the vibration intensity of the detected frequency band is When the vibration intensity is smaller than the vibration intensity in the frequency band corresponding to the fine powder ratio, it is necessary to suppress granulation. Therefore, the stirring members 111d and 112d and the pulverizing member 111e are stored in an amount preset and stored according to the difference. , 112e, and the opening of the powder take-out gate valve is increased in order to reduce the powder residence time.
Thereby, even if the particle size distribution of the powder changes during the granulation process, the coarse powder ratio or the fine powder ratio of the powder can be brought close to an arbitrary target value with high accuracy. Others are the same as the second embodiment.
[0043]
In the above embodiments, one of the coarse powder ratio and the fine powder ratio was measured. However, by providing both a signal processing device for obtaining the coarse powder ratio and a signal processing device for obtaining the fine powder ratio, both of them were measured. May be measured simultaneously. In the case where both the coarse powder ratio and the fine powder ratio are obtained in the granulation control, if the control amount based on the coarse powder ratio and the control amount based on the fine powder ratio do not match, it may be determined in advance which one should be prioritized. Further, the second and third embodiments may be combined to control the granulation end point and the granulation conditions at the same time. Instead of the crushing members 111e and 112e in the second and third embodiments, the vibration plate 6 shown in the first embodiment may be provided in each of the granulating devices 111 and 112 to detect the vibration intensity.
[0044]
【The invention's effect】
According to the present invention, it is possible to accurately determine the coarse powder ratio and the fine powder ratio as a powder property not affected by the particle size distribution of the powder, and to accurately determine the end point of granulation. In addition, it is possible to provide a granulation control method which can bring a coarse powder ratio or a fine powder ratio close to a desired value with high accuracy at the time of granulation and can contribute to quality control.
[Brief description of the drawings]
1 (1), (2), and (3) are diagrams showing particle size distributions of powders having different particle size distribution constants.
FIG. 2 is a diagram showing the relationship between the average particle size of powder constituent particles, vibration intensity in a predetermined frequency band, and a particle size distribution constant.
FIG. 3 is a configuration explanatory view for implementing a powder property measuring method according to the first embodiment of the present invention.
FIG. 4 is a configuration explanatory view of a main part for implementing a method for measuring powder properties according to the first embodiment of the present invention.
5A and 5B are diagrams illustrating a relationship between the vibration intensity in a predetermined frequency band and a coarse powder ratio in the first embodiment of the present invention, wherein FIG.
6A and 6B are diagrams illustrating a relationship between the vibration intensity in a predetermined frequency band and the fine powder ratio in the first embodiment of the present invention.
FIGS. 7 (1), (2), and (3) are diagrams illustrating vibration spectra when the thicknesses of the diaphragms are different from each other in the first embodiment of the present invention.
FIG. 8 is a diagram showing a relationship between a powder flow rate and a vibration intensity in a predetermined frequency band according to the first embodiment of the present invention.
FIG. 9 is a diagram showing the relationship between the position of powder collision with the diaphragm and the vibration intensity in a predetermined frequency band according to the first embodiment of the present invention.
FIG. 10 is a configuration explanatory view for performing granulation control in a second embodiment of the present invention.
FIG. 11 is a configuration explanatory view for performing granulation control in a third embodiment of the present invention.
[Explanation of symbols]
1 Measuring device
5 powder
6 diaphragm
8 Sensor
10 Signal processing device
111 first granulator
111e crushing member
112 Second granulator
112e crushing member
114a sensor
114b sensor
115 signal processor
115 'signal processor

Claims (4)

Vibration caused by the collision between the powder and the portion located in the flow region of the powder in the flowing state, detects the intensity of a frequency band equal to or higher than a predetermined set value including the natural frequency,
Based on a previously determined relationship between a coarse powder ratio, which is a weight ratio of particles having a set particle size or more in the powder, and a vibration intensity in the frequency band, a coarse powder ratio corresponding to the detected vibration intensity in the frequency band is obtained. Method for measuring powder properties. Vibration caused by collision of the powder with a part located in the flow region of the powder in a flowing state, detects the intensity of a frequency band equal to or less than a predetermined set value including a natural frequency,
Based on a previously determined relationship between the fine powder ratio, which is a weight ratio of particles having a particle size equal to or smaller than the set particle size, and the vibration intensity in the frequency band, the powder for obtaining the fine powder ratio corresponding to the detected vibration intensity in the frequency band. How to measure properties. When flowing the powder for granulation, at least one of the measurement of the coarse powder ratio by the method of claim 1 and the measurement of the fine powder ratio by the method of claim 2,
A granulation control method for terminating the granulation when at least one of the measured coarse powder ratio and fine powder ratio is a predetermined set value. When flowing the powder for granulation, at least one of the measurement of the coarse powder ratio by the method of claim 1 and the measurement of the fine powder ratio by the method of claim 2,
Comparison of the predetermined relationship between the elapsed time from the start of granulation and the standard coarse powder ratio of the powder and the coarse powder ratio measured at an arbitrary time after the start of the granulation, and the elapsed time from the start of the granulation Perform at least one of the predetermined relationship with the reference fine powder ratio of the powder and the comparison with the fine powder ratio measured at an arbitrary time after the start of granulation,
A granulation control method for changing granulation conditions so as to reduce at least one of the difference between the measured coarse powder ratio and the reference coarse powder ratio and the difference between the fine powder ratio and the reference fine powder ratio.

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