JP4787454B2

JP4787454B2 - Screw dehydrator

Info

Publication number: JP4787454B2
Application number: JP2002334298A
Authority: JP
Inventors: 勝俵; 与市佐藤
Original assignee: Sanki Engineering Co Ltd
Current assignee: Sanki Engineering Co Ltd
Priority date: 2002-11-18
Filing date: 2002-11-18
Publication date: 2011-10-05
Anticipated expiration: 2022-11-18
Also published as: JP2004167325A

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば重金属を含むメッキ排液や、金属微粒子を含む工場排液などのろ過原液を圧搾脱水するスクリュー脱水機に関する。
【０００２】
【従来の技術】
本発明では、超音波振動を利用してろ過スクリーンの清掃を行うものであるが、この種のスクリュー脱水機は公知である（例えば、特許文献１参照）。ろ過スクリーンを回転駆動しながら清掃を行うことも公知である（例えば、特許文献２参照）。前者の脱水機では、ろ過スクリーンの外周を覆う外筒の内部に超音波発振器が配されており、清掃時には外筒内に圧搾水を満たした状態で超音波振動子を駆動し、超音波で圧搾水を振動させてスクリーン面から汚泥を剥離除去している。
【０００３】
【特許文献１】
特開２００１−１４９７０９号公報（段落番号００１１、図１）
【特許文献２】
特開２００１−１７９４９２号公報（段落番号０００８、図１）
【０００４】
【発明が解決しようとする課題】
一般的なスクリュー脱水機におけるろ過原液の供給形態には、落差を利用してろ過原液を流下供給する形態と、ポンプを用いてろ過原液を連続送給し、設定液位を越えたろ過原液は原液タンク側へ戻す形態とがある。後者では、ポンプを用いてろ過原液をろ過室へ強制送給しているものの、圧搾スクリューの入口付近におけるろ過原液の圧力は大気圧程度しかなく、従って、ろ過原液のろ過効率は、圧搾スクリューの圧搾作用のみに依存することとなる。
【０００５】
特許文献１に係るスクリュー脱水機においては、外筒内に圧搾水を充満させた後に超音波振動子を駆動するので、外筒内に圧搾水が充満するまでの間は清掃作業を開始できず即応性に欠ける。超音波振動子が外筒内の一箇所に限って配置されているので、超音波振動子から遠く離れた個所や、ろ過スクリーンの周面全体に超音波を到達させることできず、充分な洗浄効果を得難い。
【０００６】
本発明の目的は、圧搾スクリューの脱水作用に加えて、ろ過原液を送給するポンプの送給圧力を利用してろ過原液を前段ろ過でき、その分だけろ過原液を効率よく脱水できるスクリュー脱水機を提供することにある。本発明の目的は、超音波振動を利用して、筒状のろ過スクリーンの全周面を満遍なくしかも確実に清掃でき、しかも、ろ過スクリーンの目詰まり状況に応じていつでもスクリーン清掃を行えるスクリュー脱水機を提供することにある。
【０００７】
【課題を解決するための手段】
本発明のスクリュー脱水機は、図１に示すように、全体が垂直に吊持され回転駆動される主軸２６と主軸２６の外周面に固定した螺旋ブレード２７とを備える圧搾スクリュー９と、圧搾スクリュー９の外周を囲む円筒状のろ過スクリーン１０と、ろ過スクリーン１０の周囲を囲んで垂直に支持される縦長の外殻ケース２と、外殻ケース２の上端に位置してろ過原液を導入する入口室１７と、外殻ケース２の下端に位置して脱水ケーキを排出するケーキ出口１４を有する圧搾スクリュー９の搬送終端の出口室２５と、を備える機体全体が縦長姿勢のスクリュー脱水機に関する。ろ過原液を入口室１７へ脱水運転中に連続して送給するポンプ５を備えて、圧搾スクリュー９で脱水する以前に、入口室１７内におけるろ過原液の圧力を、ポンプ５の送給圧力とほぼ一致させて維持することで、圧搾スクリュー９で脱水する前のろ過原液を、前記螺旋ブレード２７最上面と入口室１７とで囲まれる空間側面にあるろ過スクリーン１０により、前段ろ過することを特徴とする。
【０００８】
具体的には、ろ過原液の圧力を検出する入口圧力センサー１８が、入口室１７に臨んで配置されており、入口圧力センサー１８からの出力信号に基づいてポンプ５の運転状態を制御する制御装置４７を備えている。
【０００９】
圧搾スクリュー９の搬送終端の出口室２５に臨んで、ケーキ出口１４と、ケーキ出口１４の開量を調整する開量調整弁２４と、出口圧力センサー１９とが設けられており、出口圧力センサー１９からの出力信号に基づいて開量調整弁２４の開量を制御する制御装置４７を備えている。出口圧力センサー１９の設定値が、入口圧力センサー１８の設定値よりも大きくなるように設定してある。
【００１０】
外殻ケース２に超音波振動を発振する複数個の超音波発振器４２が、ろ過スクリーン１０と対向する状態で分散配置されており、機体外面に設けた駆動機構４でろ過スクリーン１０を低速度で回転駆動できる。
【００１１】
機体全体は縦長姿勢で配置して、外殻ケース２の上部にろ液の排液口２１を設け、排液口２１で規定されるろ液の液位Ｌより下側の外殻ケース２の周面に、複数個の超音波発振器４２を上下に隣接する状態で直線列状に配置することができる。
【００１２】
ろ過スクリーン１０の上下両端に設けた回転リング２９・３０は、外郭ケース２と回転リング２９・３０との間に設けた軸受３１を介して回転自在に支持し、駆動機構４が、モーター３６と、ろ過スクリーン１０の下端に固定したスクリーン軸３５と、モーター動力をスクリーン軸３５に伝動する巻掛伝動機構とで構成されている。
【００１３】
【発明の作用効果】
本発明のスクリュー脱水機では、圧搾スクリュー９で脱水する以前に、入口室１７内におけるろ過原液の圧力を、ポンプ５の送給圧力とほぼ一致させて前段ろ過するので、前段ろ過した分だけ圧搾スクリュー９による圧搾負荷を軽減して、ろ過原液を効率よく脱水できる。
【００１４】
入口室１７に設けた入口圧力センサー１８からの出力信号に基づいてポンプ５の運転状態を制御装置４７で制御して、前段ろ過を行うスクリュー脱水機によれば、入口室１７内の圧力を常に適正な圧力範囲に維持して、前段脱水を常に適正に行える。
【００１５】
出口室２５に設けたケーキ出口１４に、ケーキ出口１４の開量を調整する開量調整弁２４を設け、出口圧力センサー１９からの出力信号に基づいて開量調整弁２４の開量を制御装置４７で制御できるようにしたスクリュー脱水機によれば、出口室２５内の圧力は、常に適正な圧力範囲に維持できるので、例えば、ろ過隙間に固形物が詰まって、ろ過スクリーン１０が早期に目詰まり状態に陥るのを確実に防止できる。開量調整弁２４の開放量を調整することにより、螺旋ブレード２７に作用する背圧を大小に変更調整できるので、脱水ケーキの状況に応じて開量調整弁２４の開放量を随時調整でき、従来のゲート機構によって背圧を設定する場合に比べて、脱水ケーキの硬さあるいは軟らかさを柔軟に変更できる。
【００１６】
外殻ケース２に超音波発振器４２が、ろ過スクリーン１０と対向する状態で分散配置され、機体外面に設けた駆動機構４でろ過スクリーン１０を低速度で回転駆動できるようにしたスクリュー脱水機によれば、ろ過スクリーン１０が目詰まりした場合には、圧搾作業を中断した後、超音波発振器４２と駆動機構４を駆動するだけで、超音波発振器４２で発生した超音波をろ過スクリーン１０の全周囲に対して均等に作用させて、ろ過隙間の洗浄を確実にしかも短時間で行え、さらにろ過スクリーンの目詰まり状況に応じていつでもスクリーン清掃を行って、脱水機能を適正な状態に回復させることができる。
【００１７】
機体全体を縦長姿勢で配置して、外殻ケース２の上部にろ液の排液口２１を設けて、排液口２１で規定されるろ液の液位Ｌより下側の外殻ケース２の周面に、複数個の超音波発振器４２を上下に隣接する状態で直線列状に配置したスクリュー脱水機によれば、ろ液の充満を待つ必要もなく、ろ過隙間の清掃が簡便にしかも即座に行えるうえ、外殻ケース２の周面に配置した複数個の超音波発振器４２でろ過スクリーン１０の周囲を均等にむらなく洗浄して、脱水機能を効果的に回復できる。また、各超音波発振器４２の本体部分を外殻ケース２の周面に配置するので、外殻ケース２やろ過スクリーン１０などを分解する必要もなく、超音波発振器４２の点検や交換等の補修作業が少ない手間で簡単に行える。縦長に構成したスクリュー脱水機は、その設置スペースが少なくて済む利点もある。
【００１８】
ろ過スクリーン１０の上下両端に回転リング２９・３０を設け、外郭ケース２と回転リング２９・３０との間に設けた軸受３１を介して、ろ過スクリーン１０の全体を回転自在に支持すると、駆動機構４で回転駆動されるろ過スクリーン１０を、圧搾スクリュー９とろ過スクリーン１０との圧搾隙間を適正化して、圧搾むらを解消できる。モーター３６と、ろ過スクリーン１０の下端に固定したスクリーン軸３５と、両者間に設けた巻掛伝動機構とで駆動機構４が構成されていると、駆動機構４の殆どを機外に配置できるので、駆動動力をスクリーン軸３５に対して確実に伝動でき、その保守作業も簡便に行える。
【００１９】
【実施例】
図１ないし図６は本発明に係るスクリュー脱水機の実施例を示す。図２においてスクリュー脱水機は、スタンド１に垂直に支持される縦長の外殻ケース２と、外殻ケース２の上端に配置される減速機付きのモーター３と、外殻ケース２の他側端に設けられる駆動機構４と、ろ過原液を加圧送給するポンプ５とからなる。
【００２０】
外殻ケース２は、スタンド１に固定支持される主ケース６と、主ケース６の上下端に固定される上ケース７および下ケース８とに分割してあり、その内部に圧搾スクリュー９とろ過スクリーン１０とを収容してある。上ケース７の上面一側にはろ過原液の入口１３が、下ケース８の下面一側には脱水ケーキの出口、すなわちケーキ出口１４が、それぞれ開口している。
【００２１】
図１において上ケース７は、下向きに開口する筒状のケースからなり、ケース上壁にモーター３が固定され、ケース内に突出するモーター３の出力軸３ａに圧搾スクリュー９の上端の駆動軸９ａが連結されている。駆動軸９ａはケース上壁のボスに装填したベアリング１５で軸支してあり、シールリング１６でシールしてある。上ケース７の内部は、ろ過原液を貯留する入口室１７になっており、その上壁に入口室１７におけるろ過原液の圧力を検知する入口圧力センサー１８が配置されている。
【００２２】
主ケース６は上下両端が開口する筒ケースからなり、周面一箇所に超音波発信器を装着するためのハウジング２０が膨出形成されている。主ケース６の筒壁の上端一側には、ろ液を回収する排液口２１を設けてある。このように、外殻ケース２の上部に排液口２１が設けられていると、外殻ケース２の内部をろ液で常に満たして、図１の符号Ｌで示す液位より下方に位置する、圧搾スクリュー９およびろ過スクリーン１０の殆どの部分と、ハウジング２０の全体とをろ液に浸漬させておくことができる。
【００２３】
下ケース８は、上下面が開口する筒ケース８ａと、筒ケース８ａの下面に固定される底蓋８ｂとで構成してあり、底蓋８ｂの一側にケーキ出口１４を設け、中央のボスに装着したベアリング２３で、後述するスクリーン軸３５を回転自在に軸支している。ケーキ出口１４には開量調整弁２４が装着してあり、図外のエアーシリンダーで開量調整弁２４の開量を調整することにより、圧搾スクリュー９に作用する背圧を大小に調整変更して、圧搾圧力を変更できる。開量調整弁２４は例えばボール弁で構成してある。
【００２４】
下ケース８の内部は脱水ケーキを貯留する出口室２５になっており、底蓋８ｂに脱水ケーキの圧力を検知する出口圧力センサー１９が配置されている。
【００２５】
圧搾スクリュー９は、中空の主軸２６と、その外周囲に固定した螺旋ブレード２７と、主軸２６の上端に突出する駆動軸９ａと、主軸２６の下端に突出する下軸９ｂとからなり、全体が垂直に吊持されている。主軸２６とろ過スクリーン１０との間隔が大きいと、ろ過スクリーン１０に近い側の圧搾対象のみが圧搾されて、主軸２６に近い側の圧搾対象が圧搾されにくい。そこでこの実施例では、主軸２６の外周面とろ過スクリーン１０の内周面との間隔を２０mmとして、圧搾対象を均一に脱水できるようにした。この間隔は圧搾対象によって１０〜３０mmの範囲で選択できる。螺旋ブレード２７は搬送始端から搬送終端へ向かって同径、同ピッチで形成してある。
【００２６】
図４においてろ過スクリーン１０は、耐圧性に優れたウエッジワイヤー１０ａをろ過要素にして、その周面に図外の補強リングを固定して円筒状に形成されており、その上下両端に回転リング２９・３０を固定してある。主ケース６内にろ過スクリーン１０を差し込み、上下の回転リング２９・３０に設けた軸受３１を主ケース６および下ケース８で軸支することにより、ろ過スクリーン１０の全体を回転自在に支持できる。
【００２７】
軸受３１は四ふっかエチレンや超高分子樹脂（ＵＨＭＷ）などを素材とする樹脂製のリングからなり、下側の回転リング３０を支持する軸受３１には、ラジアル荷重を負担する筒壁に加えて、スラスト荷重を受けるフランジが張り出し形成されてある。ろ過スクリーン１０の内面上下の２箇所には、螺旋ブレード２７で圧搾した脱水ケーキのスリップを防ぐ突起３２が、それぞれ対向状に設けてある。螺旋ブレード２７には、突起３２との接当干渉を防ぐ切り欠きを設けてある。符号３３はシールリングである。
【００２８】
ろ過スクリーン１０を回転駆動するために、図６に示すように下側の回転リング３０の内面に十文字状の支持腕３４を固定し、その中央にスクリーン軸３５が固定されている。スクリーン軸３５は圧搾スクリュー９の下端に突出する下軸９ｂの軸受体を兼ねており、軸内面に嵌め込んだ軸受３６で下軸９ｂを軸支している。軸受３６は先の軸受３１と同じ素材で形成してある。
【００２９】
このように、圧搾スクリュー９の下軸９ｂがスクリーン軸３５で支えられていると、圧搾スクリュー９の下側の回転中心がぶれ動くのを規制して、圧搾スクリュー９を適正に回転駆動できる。スクリーン軸３５は、下ケース８の底蓋８ｂを上下に貫通する状態で設けてあり、脱水機の機外に設けた駆動機構４で回転駆動される。
【００３０】
駆動機構４は、モーター３６と、その出力軸に固定した原動ギヤ３７と、スクリーン軸３５に固定した従動ギヤ３８と、両ギヤ３７・３８に巻き掛けたチェーン３９とからなり、ろ過スクリーン１０を圧搾スクリュー９の回転方向とは逆向きに低速度（１〜２ｒｐｍ）で回転駆動する。両ギヤ３７・３８と、両ギヤ３７・３８に巻き掛けたチェーン３９とで巻掛伝動機構が構成されている。
【００３１】
上記構成のスクリュー脱水機において、目詰まり状態に陥ったろ過スクリーン１０のろ過隙間を清掃して脱水機能を回復するために、主ケース６のハウジング２０に多数個（７個）の超音波発振器４２が設けられている。この超音波発信器４０は市販品からなり、各超音波発振器４２は主ケース６の上下長手方向に沿って直線列状に分散配置され、図４に示すようにその発振部４３をハウジング２０内に臨ませて、発振部４３がろ過スクリーン１０の周面と対向するように取り付けてある。発振部４３における超音波の発振角度は６０度の広がりをもっており、ろ過スクリーン１０の外面においては、上下に隣接する超音波発信器４２から発振された超音波の到達領域どうしが上下に重なっている。
【００３２】
従来は、ろ過原液に高分子凝集剤を加えて微粒子を凝集したうえで、この凝集液をスクリュー脱水機で圧搾することにより、微粒子を含まない水分と脱水ケーキとに分離していたが、本発明のスクリュー脱水機においては、高分子凝集剤による前処理を省略して汚泥原液を直接圧搾する。
【００３３】
具体的には、図３に示すごとくろ過原液槽４４に貯留したろ過原液をポンプ５で入口１３を介して入口室１７へ加圧送給し、入口室１７内の液圧をポンプ５の送給圧力と同じ状態に維持することにより、圧搾スクリュー９で圧搾される前のろ過原液をろ過スクリーン１０でろ過する。つまり、前段ろ過を行って、圧搾スクリュー９の脱水負荷を軽減する。
【００３４】
そのために、図１に示す入口圧力センサー１８で入口室１７の圧力を検出し、この検知信号に基づいてポンプ５を制御装置４７で制御している。詳しくは、入口室１７の圧力が一定値を越えた状態では、ポンプ５の送給量を減少し、入口室１７の圧力が一定値未満になると、ポンプ５の送給量を増加するように制御する。符号４８は圧力調整弁であり、ポンプ５の送給圧力が異常に上昇した場合に送給圧を低減するために設けてある。
【００３５】
開量調整弁２４の制御も制御装置４７で同様にして行う。図４に示すように、出口室２５の圧力を出口圧力センサー１９で検知し、出口室２５の圧力が一定値を越えた状態では、開量調整弁２４の開量を増加し、出口室２５の圧力が一定値以下になると、開量調整弁２４の開量を減少するように制御する。
【００３６】
なお、脱水対象によっても異なるが、入口圧力センサー１８の設定圧力は１〜３kg／cm² の範囲で選択でき、出口圧力センサー１９の設定圧力は1.５〜４kg／cm² の範囲で選択でき、常に出口圧力センサー１９の設定圧力のほうが大きく設定される。
【００３７】
前段ろ過された後のろ過原液は、螺旋ブレード２７で出口室２５へ向かって押し込まれ、出口室２５へ到達するまでの間に圧搾脱水される。このとき、搬送終端付近の螺旋ブレード２７に作用する背圧は、開量調整弁２４の絞り作用に伴う通過抵抗によって規定される。開量調整弁２４を通り抜けた脱水ケーキは、ケーキ容器４５に収容される。ろ過スクリーン１０を通り抜けたろ液は、排液口２１から排出されて排液槽４６に回収される。
【００３８】
例えば、排液口２１からのろ液の流量が一定量未満になると、これを図外の流量センサーで検知することにより、ろ過スクリーン１０が目詰まり状態になっていることが判る。その場合には、まずポンプ５によるろ過原液の送給を停止し、さらにモーター３を逆転駆動して脱水ケーキをほぐし含水させて軟らかくする。
【００３９】
この状態で、ろ過スクリーン１０をゆっくりと回転駆動しながら、超音波発振器４２を駆動し、主ケース６内に充満する圧搾水を介して振動波を作用させると、ろ過スクリーン１０の全周面のろ過隙間に付着の固形物が振動を受けて剥離される。振動波を受けたウエッジワイヤー１０ａこれ自体が振動することによっても、ろ過隙間に付着している固形物が振り落とされる。このとき、超音波発振器４２は一斉に駆動してもよいし、隣接する超音波発振器４２を交互に駆動して、振動波がろ過スクリーン１０に対して異なる位置から交互に到達するようにしてもよい。清掃終了後に、ろ過源液をポンプ５でろ過スクリーン１０内へ送給して、圧搾スクリュー９による圧搾を再開する。
【００４０】
上記以外に、外殻ケース２は圧搾スクリュー９の中心軸が斜めに傾く状態で配置してもよく、その場合には排液口２１は主ケース６の上部に設けて、圧搾スクリュー９とろ過スクリーン１０の大半の部分がろ液中に浸漬されるようにする。
【００４１】
超音波発振器４２の配置形態は、図示例で説明した配置形態と異なっていてもよく、例えば主ケース６の周面に螺旋状に分散配置することができる。要は、超音波の到達領域が上下重なる状態で配置されていればよい。超音波発振器４２はその発振部４３が主ケース６の外周面に密着する状態で配置してもよい。本発明のスクリュー脱水機は、土木建設現場、化学工場、食品工場、製紙工場などにおいて含水物を圧搾する用途に使用できる。
【００４２】
圧搾スクリュー９は先すぼまり形状や、末広がり形状になっていてもよい。螺旋ブレード２７はケーキ出口１４に近づくに従ってそのピッチが小さくなるようにすることができる。実施例で説明した外殻ケース２は上下を反転して、ケーキ出口１４を上端に設け、さらに排液口２１をケーキ出口１４の近傍に設けてもよい。
【００４３】
スタンド１の支持対象は主ケース６であってもよいし、上ケース７と主ケース６との双方であってもよい。開量調整弁２４に換えて、筒ケース８ａの開口を塞ぐゲート機構を設け、ばねや流体圧シリンダでゲート体を閉じ付勢してもよい。ろ過スクリーン１０は、必ずしもウエッジワイヤーをろ過要素とする必要はなく、パンチングメタルや、複数種のろ過要素を内外に重ねて形成されていてもよい。
【図面の簡単な説明】
【図１】スクリュー脱水機の入口室側の縦断側面図
【図２】スクリュー脱水機の概略縦断側面図
【図３】スクリュー脱水機の全体側面図
【図４】スクリュー脱水機の出口室側の縦断側面図
【図５】図４におけるＡ−Ａ線断面図
【図６】図４におけるＢ−Ｂ線断面図
【符号の説明】
２外殻ケース
４駆動機構
５ポンプ
９圧搾スクリュー
１０ろ過スクリーン
１４ケーキ出口
１７入口室
１８入口圧力センサー
１９出口圧力センサー
２１排液口
２４開量調整弁
２５出口室
２９・３０回転リング
３５スクリーン軸
３６モーター
４２超音波発振器
４７制御装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw dehydrator that squeezes and dehydrates a filtrate stock such as a plating effluent containing heavy metals and a factory effluent containing metal fine particles.
[0002]
[Prior art]
In the present invention, the filtration screen is cleaned using ultrasonic vibration. This type of screw dehydrator is known (for example, see Patent Document 1). It is also known to perform cleaning while rotating the filtration screen (see, for example, Patent Document 2). In the former dehydrator, an ultrasonic oscillator is arranged inside the outer cylinder that covers the outer periphery of the filtration screen, and when cleaning, the ultrasonic vibrator is driven in a state where the outer cylinder is filled with compressed water. The compressed water is vibrated to remove and remove sludge from the screen surface.
[0003]
[Patent Document 1]
JP 2001-149709 A (paragraph number 0011, FIG. 1)
[Patent Document 2]
JP 2001-179492 A (paragraph number 0008, FIG. 1)
[0004]
[Problems to be solved by the invention]
In the supply form of the filtrate stock solution in a general screw dehydrator, the filtrate stock solution is fed down using a head, and the filtrate stock solution is continuously fed using a pump. There is a form to return to the stock solution tank side. In the latter case, although the filtrate is forcibly fed to the filtration chamber using a pump, the pressure of the filtrate concentrate in the vicinity of the inlet of the squeeze screw is only about atmospheric pressure, and therefore the filtration efficiency of the filtrate concentrate is the same as that of the squeeze screw. It depends only on the pressing action.
[0005]
In the screw dehydrator according to Patent Literature 1, since the ultrasonic vibrator is driven after the outer cylinder is filled with the compressed water, the cleaning operation cannot be started until the outer cylinder is filled with the compressed water. Lack of responsiveness. Since the ultrasonic transducer is arranged only at one location in the outer cylinder, the ultrasonic wave cannot reach the part far away from the ultrasonic transducer or the entire peripheral surface of the filtration screen, so it can be cleaned sufficiently It is difficult to obtain an effect.
[0006]
The object of the present invention is to provide a screw dehydrator capable of pre-filtering the filtered stock solution using the feed pressure of a pump that feeds the filtered stock solution in addition to the dehydrating action of the compression screw, and efficiently dewatering the filtered stock solution accordingly. Is to provide. An object of the present invention is to provide a screw dehydrator that can clean the entire circumferential surface of a cylindrical filtration screen evenly and reliably using ultrasonic vibration, and can always clean the screen according to the clogging condition of the filtration screen. Is to provide.
[0007]
[Means for Solving the Problems]
As shown in FIG. 1, the screw dehydrator of the present invention includes a main screw 26 that is vertically suspended and rotationally driven, and a press screw 9 that includes a spiral blade 27 fixed to the outer peripheral surface of the main shaft 26, and a press screw a cylindrical filtration screen 10 surrounding the outer periphery of 9, the outer shell case 2 of elongated supported vertically Nde around circumference of the filtration screen 10, an inlet for introducing the filtered stock solution is located at the upper end of the outer shell case 2 The entire machine body including a chamber 17 and an outlet chamber 25 at the conveyance end of the pressing screw 9 having a cake outlet 14 that is located at the lower end of the outer shell case 2 and discharges the dehydrated cake relates to a screw dehydrator having a vertically long posture. Filtered stock solution comprises a pump 5 for feeding continuously during dewatering operation to the inlet chamber 17, prior to dewatering by squeezing screw 9, the pressure of the filtered stock solution at the inlet chamber 17, a feed pressure of the pump 5 By maintaining substantially the same, the filtered raw solution before being dehydrated by the pressing screw 9 is subjected to pre-filtration by the filtration screen 10 on the side surface of the space surrounded by the uppermost surface of the spiral blade 27 and the inlet chamber 17. And
[0008]
Specifically, an inlet pressure sensor 18 that detects the pressure of the filtrate concentrate is disposed facing the inlet chamber 17, and controls the operating state of the pump 5 based on an output signal from the inlet pressure sensor 18. 47 is provided.
[0009]
Facing the exit chamber 25 at the conveyance end of the pressing screw 9, a cake outlet 14, an opening amount adjusting valve 24 for adjusting the opening amount of the cake outlet 14, and an outlet pressure sensor 19 are provided. Is provided with a control device 47 for controlling the opening amount of the opening amount adjusting valve 24 on the basis of the output signal from. The set value of the outlet pressure sensor 19 is set to be larger than the set value of the inlet pressure sensor 18.
[0010]
A plurality of ultrasonic oscillators 42 that oscillate ultrasonic vibrations are distributed in the outer shell case 2 so as to face the filtration screen 10, and the filtration screen 10 is moved at a low speed by the drive mechanism 4 provided on the outer surface of the machine body. Can be rotated.
[0011]
The entire body is arranged in a vertically long posture, and a filtrate drain port 21 is provided at the top of the outer shell case 2, and the outer shell case 2 below the filtrate level L defined by the drain port 21 is provided. A plurality of ultrasonic oscillators 42 can be arranged in a straight line on the circumferential surface in a state where they are vertically adjacent.
[0012]
Rotating rings 29 and 30 provided at both upper and lower ends of the filtration screen 10 are rotatably supported via bearings 31 provided between the outer case 2 and the rotating rings 29 and 30, and the drive mechanism 4 is connected to the motor 36. The screen shaft 35 fixed to the lower end of the filtration screen 10 and a winding transmission mechanism that transmits motor power to the screen shaft 35 are configured.
[0013]
[Effects of the invention]
In the screw dehydrator according to the present invention, before the dehydration by the pressing screw 9, the pre-filtration is performed so that the pressure of the filtrate stock in the inlet chamber 17 is substantially the same as the supply pressure of the pump 5, so that the pre-filtered portion is compressed. The compression load by the screw 9 can be reduced, and the filtrate stock can be efficiently dehydrated.
[0014]
According to the screw dehydrator that controls the operation state of the pump 5 with the control device 47 based on the output signal from the inlet pressure sensor 18 provided in the inlet chamber 17 and performs pre-stage filtration, the pressure in the inlet chamber 17 is always maintained. Maintaining an appropriate pressure range, the previous stage dewatering can always be performed properly.
[0015]
An opening amount adjusting valve 24 for adjusting the opening amount of the cake outlet 14 is provided at the cake outlet 14 provided in the outlet chamber 25, and the opening amount of the opening amount adjusting valve 24 is controlled based on an output signal from the outlet pressure sensor 19. According to the screw dehydrator that can be controlled by 47, the pressure in the outlet chamber 25 can always be maintained in an appropriate pressure range. For example, solid matter is clogged in the filtration gap, and the filtration screen 10 can be quickly observed. It is possible to reliably prevent clogging. By adjusting the opening amount of the opening amount adjusting valve 24, the back pressure acting on the spiral blade 27 can be adjusted to be larger or smaller, so that the opening amount of the opening amount adjusting valve 24 can be adjusted at any time according to the state of the dehydrated cake, Compared with the case where the back pressure is set by the conventional gate mechanism, the hardness or softness of the dewatered cake can be changed flexibly.
[0016]
According to the screw dehydrator in which the ultrasonic oscillator 42 is dispersedly arranged in the outer shell case 2 so as to face the filtration screen 10 and the filtration screen 10 can be rotated at a low speed by the drive mechanism 4 provided on the outer surface of the machine body. For example, when the filtration screen 10 is clogged, the squeezing operation is interrupted, and then the ultrasonic oscillator 42 and the drive mechanism 4 are driven, and the ultrasonic waves generated by the ultrasonic oscillator 42 are all around the filtration screen 10. The filter can be cleaned evenly in a short time, and the screen can be cleaned whenever the filter screen is clogged to restore the dehydration function to an appropriate state. it can.
[0017]
The entire machine body is arranged in a vertically long posture, and a filtrate drain port 21 is provided at the upper part of the outer shell case 2, and the outer shell case 2 below the filtrate level L defined by the drain port 21. According to the screw dehydrator in which a plurality of ultrasonic oscillators 42 are arranged in a straight line with the upper and lower sides adjacent to each other on the peripheral surface, there is no need to wait for the filtrate to be filled, and the filtration gap can be easily cleaned. The dehydrating function can be effectively restored by cleaning the periphery of the filtration screen 10 evenly with the plurality of ultrasonic oscillators 42 arranged on the peripheral surface of the outer shell case 2 in an even manner. Further, since the main body portion of each ultrasonic oscillator 42 is disposed on the peripheral surface of the outer shell case 2, it is not necessary to disassemble the outer shell case 2, the filtration screen 10, etc., and repairs such as inspection and replacement of the ultrasonic oscillator 42 are performed. It can be done easily with less work. The screw dehydrator configured vertically is advantageous in that the installation space is small.
[0018]
When the rotary screens 29 and 30 are provided at both upper and lower ends of the filtration screen 10 and the entire filtration screen 10 is rotatably supported via a bearing 31 provided between the outer case 2 and the rotary rings 29 and 30, a driving mechanism is provided. By optimizing the squeezing gap between the squeezing screw 9 and the filtering screen 10, the squeezing unevenness can be eliminated. If the drive mechanism 4 is composed of the motor 36, the screen shaft 35 fixed to the lower end of the filtration screen 10, and the winding transmission mechanism provided between them, most of the drive mechanism 4 can be arranged outside the machine. The driving power can be reliably transmitted to the screen shaft 35, and the maintenance work can be easily performed.
[0019]
【Example】
1 to 6 show an embodiment of a screw dehydrator according to the present invention. In FIG. 2, the screw dehydrator includes a vertically long outer shell case 2 that is vertically supported by the stand 1, a motor 3 with a speed reducer disposed at the upper end of the outer shell case 2, and the other side end of the outer shell case 2. And a pump 5 for feeding the filtrate solution under pressure.
[0020]
The outer shell case 2 is divided into a main case 6 fixedly supported on the stand 1, and an upper case 7 and a lower case 8 fixed to the upper and lower ends of the main case 6. A screen 10 is accommodated. An inlet 13 for the filtrate solution is opened on one side of the upper surface of the upper case 7, and an outlet for dehydrated cake, that is, a cake outlet 14 is opened on the lower surface of the lower case 8.
[0021]
1, the upper case 7 is formed of a cylindrical case that opens downward, the motor 3 is fixed to the upper wall of the case, the output shaft 3a of the motor 3 protruding into the case, and the drive shaft 9a at the upper end of the squeezing screw 9 Are connected. The drive shaft 9 a is pivotally supported by a bearing 15 loaded on a boss on the upper wall of the case, and is sealed by a seal ring 16. Inside the upper case 7 is an inlet chamber 17 for storing the filtrate stock solution, and an inlet pressure sensor 18 for detecting the pressure of the filtrate stock solution in the inlet chamber 17 is arranged on the upper wall thereof.
[0022]
The main case 6 is formed of a cylindrical case that is open at both upper and lower ends, and a housing 20 for mounting an ultrasonic transmitter is bulged and formed at one place on the peripheral surface. A drainage port 21 for collecting the filtrate is provided on one side of the upper end of the cylindrical wall of the main case 6. Thus, if the drainage port 21 is provided in the upper part of the outer shell case 2, the inside of the outer shell case 2 is always filled with the filtrate, and is positioned below the liquid level indicated by the symbol L in FIG. The most part of the pressing screw 9 and the filtration screen 10 and the entire housing 20 can be immersed in the filtrate.
[0023]
The lower case 8 includes a cylindrical case 8a whose upper and lower surfaces are open, and a bottom lid 8b fixed to the lower surface of the cylindrical case 8a. A cake outlet 14 is provided on one side of the bottom lid 8b, and a central boss is provided. A screen shaft 35 described later is rotatably supported by a bearing 23 attached to the shaft. An opening amount adjusting valve 24 is attached to the cake outlet 14, and the back pressure acting on the squeezing screw 9 is adjusted to be larger or smaller by adjusting the opening amount of the opening amount adjusting valve 24 with an air cylinder (not shown). The pressing pressure can be changed. The opening amount adjusting valve 24 is constituted by a ball valve, for example.
[0024]
The inside of the lower case 8 is an outlet chamber 25 for storing dehydrated cake, and an outlet pressure sensor 19 for detecting the pressure of the dehydrated cake is disposed on the bottom lid 8b.
[0025]
The compression screw 9 includes a hollow main shaft 26, a spiral blade 27 fixed to the outer periphery thereof, a drive shaft 9a protruding at the upper end of the main shaft 26, and a lower shaft 9b protruding at the lower end of the main shaft 26. It is suspended vertically. When the space | interval of the main axis | shaft 26 and the filtration screen 10 is large, only the squeezing object near the filtration screen 10 is squeezed, and the squeezing object near the main axis 26 is difficult to be squeezed. Therefore, in this embodiment, the distance between the outer peripheral surface of the main shaft 26 and the inner peripheral surface of the filtration screen 10 is set to 20 mm so that the object to be squeezed can be dehydrated uniformly. This space | interval can be selected in the range of 10-30 mm by the pressing object. The spiral blades 27 are formed with the same diameter and the same pitch from the conveyance start end toward the conveyance end.
[0026]
In FIG. 4, the filtration screen 10 is formed in a cylindrical shape by using a wedge wire 10a having excellent pressure resistance as a filtration element, and a reinforcing ring (not shown) is fixed to the peripheral surface thereof.・ 30 is fixed. The entire filtration screen 10 can be rotatably supported by inserting the filtration screen 10 into the main case 6 and pivotally supporting the bearings 31 provided on the upper and lower rotary rings 29 and 30 with the main case 6 and the lower case 8.
[0027]
The bearing 31 is made of a resin ring made of tetrafluoroethylene, ultra high polymer resin (UHMW), or the like. The bearing 31 supporting the lower rotating ring 30 has a cylindrical wall bearing a radial load. Thus, a flange that receives a thrust load is formed in an overhanging manner. Protrusions 32 that prevent slipping of the dewatered cake squeezed by the spiral blade 27 are provided at two locations above and below the inner surface of the filtration screen 10, respectively. The spiral blade 27 is provided with a notch that prevents contact interference with the protrusion 32. Reference numeral 33 denotes a seal ring.
[0028]
In order to rotationally drive the filtration screen 10, as shown in FIG. 6, a cross-shaped support arm 34 is fixed to the inner surface of the lower rotary ring 30, and a screen shaft 35 is fixed to the center thereof. The screen shaft 35 also serves as a bearing body for the lower shaft 9b protruding from the lower end of the pressing screw 9, and supports the lower shaft 9b with a bearing 36 fitted on the inner surface of the shaft. The bearing 36 is made of the same material as the previous bearing 31.
[0029]
Thus, if the lower shaft 9b of the pressing screw 9 is supported by the screen shaft 35, the lower rotation center of the pressing screw 9 is restricted from moving and the pressing screw 9 can be driven to rotate appropriately. The screen shaft 35 is provided in a state of vertically passing through the bottom lid 8b of the lower case 8, and is rotationally driven by the drive mechanism 4 provided outside the dehydrator.
[0030]
The drive mechanism 4 includes a motor 36, a driving gear 37 fixed to the output shaft thereof, a driven gear 38 fixed to the screen shaft 35, and a chain 39 wound around both gears 37 and 38. The rotary screw 9 is rotationally driven at a low speed (1 to 2 rpm) in the direction opposite to the rotational direction of the pressing screw 9. The both gears 37 and 38 and the chain 39 wound around both the gears 37 and 38 constitute a winding transmission mechanism.
[0031]
In the screw dehydrator configured as described above, a large number (seven) of ultrasonic oscillators 42 are provided in the housing 20 of the main case 6 in order to restore the dewatering function by cleaning the filtration gap of the filtration screen 10 that has become clogged. Is provided. This ultrasonic transmitter 40 is a commercially available product, and each ultrasonic oscillator 42 is distributed and arranged in a straight line along the vertical direction of the main case 6. As shown in FIG. The oscillator 43 is attached so as to face the peripheral surface of the filtration screen 10. The oscillating angle of the ultrasonic wave in the oscillating unit 43 has a spread of 60 degrees, and on the outer surface of the filtration screen 10, the arrival areas of the ultrasonic waves oscillated from the ultrasonic transmitters 42 adjacent to each other overlap vertically. .
[0032]
In the past, the polymer flocculant was added to the filtered stock solution to agglomerate the fine particles, and this agglomerated liquid was squeezed with a screw dehydrator to separate the water and fine cake without fine particles. In the screw dehydrator of the invention, the pretreatment with the polymer flocculant is omitted and the sludge stock solution is directly squeezed.
[0033]
Specifically, as shown in FIG. 3, the filtrate stock solution stored in the filtrate stock solution tank 44 is pressurized and fed to the inlet chamber 17 through the inlet 13 by the pump 5, and the fluid pressure in the inlet chamber 17 is fed by the pump 5. By maintaining the same state as the pressure, the filtrate stock solution before being squeezed with the squeezing screw 9 is filtered by the filtration screen 10. That is, pre-stage filtration is performed to reduce the dehydration load of the pressing screw 9.
[0034]
For this purpose, the pressure in the inlet chamber 17 is detected by the inlet pressure sensor 18 shown in FIG. 1, and the pump 5 is controlled by the controller 47 based on this detection signal. Specifically, in a state where the pressure in the inlet chamber 17 exceeds a certain value, the feed amount of the pump 5 is decreased, and when the pressure in the inlet chamber 17 becomes less than a certain value, the feed amount of the pump 5 is increased. Control. Reference numeral 48 denotes a pressure adjusting valve, which is provided to reduce the supply pressure when the supply pressure of the pump 5 rises abnormally.
[0035]
The control of the opening amount adjusting valve 24 is similarly performed by the control device 47. As shown in FIG. 4, when the pressure in the outlet chamber 25 is detected by the outlet pressure sensor 19 and the pressure in the outlet chamber 25 exceeds a certain value, the opening amount of the opening amount adjusting valve 24 is increased, and the outlet chamber 25 is increased. When the pressure becomes lower than a certain value, the opening amount of the opening amount adjusting valve 24 is controlled to decrease.
[0036]
In addition, although it changes with dehydration objects, the set pressure of the inlet pressure sensor 18 can be selected in the range of 1 to ³ kg / cm ² , and the set pressure of the outlet pressure sensor 19 can be selected in the range of 1.5 to 4 kg / cm ^2. The set pressure of the outlet pressure sensor 19 is always set larger.
[0037]
The filtered stock solution after the preceding filtration is pushed toward the outlet chamber 25 by the spiral blade 27 and is pressed and dehydrated before reaching the outlet chamber 25. At this time, the back pressure acting on the spiral blade 27 in the vicinity of the conveyance end is defined by the passage resistance accompanying the throttle action of the opening amount adjusting valve 24. The dehydrated cake that has passed through the opening amount adjusting valve 24 is accommodated in the cake container 45. The filtrate that has passed through the filtration screen 10 is discharged from the drain port 21 and collected in the drain tank 46.
[0038]
For example, when the flow rate of the filtrate from the drainage port 21 becomes less than a certain amount, it is found that the filtration screen 10 is clogged by detecting this with a flow sensor outside the figure. In that case, the supply of the filtrate stock solution by the pump 5 is first stopped, and the motor 3 is driven in reverse to loosen the dehydrated cake and make it soft so as to soften it.
[0039]
In this state, when the ultrasonic oscillator 42 is driven while slowly driving the filtration screen 10 to rotate, and a vibration wave is applied via the compressed water filled in the main case 6, the entire circumferential surface of the filtration screen 10 is driven. Solid matter adhering to the filtration gap is peeled off by vibration. The solid matter adhering to the filtration gap is also shaken off when the wedge wire 10a itself that has received the vibration wave vibrates. At this time, the ultrasonic oscillators 42 may be driven all at once, or the adjacent ultrasonic oscillators 42 may be alternately driven so that the vibration waves alternately reach the filtration screen 10 from different positions. Good. After completion of cleaning, the filtration source liquid is fed into the filtration screen 10 by the pump 5 and the squeezing by the squeezing screw 9 is resumed.
[0040]
In addition to the above, the outer shell case 2 may be disposed in a state where the central axis of the pressing screw 9 is inclined, and in that case, the drain port 21 is provided at the upper part of the main case 6 and the pressing screw 9 and the filtering screw 9 are filtered. The majority of the screen 10 is immersed in the filtrate.
[0041]
The arrangement form of the ultrasonic oscillators 42 may be different from the arrangement form described in the illustrated example. For example, the ultrasonic oscillator 42 may be arranged in a spiral manner on the peripheral surface of the main case 6. In short, it suffices if the ultrasonic wave arrival areas are arranged so as to overlap each other. The ultrasonic oscillator 42 may be disposed in a state in which the oscillating portion 43 is in close contact with the outer peripheral surface of the main case 6. The screw dehydrator of the present invention can be used for squeezing hydrated materials at civil engineering construction sites, chemical factories, food factories, paper factories and the like.
[0042]
The pressing screw 9 may have a tapered shape or a divergent shape. The pitch of the spiral blade 27 can be reduced as it approaches the cake outlet 14. The outer shell case 2 described in the embodiment may be turned upside down, the cake outlet 14 may be provided at the upper end, and the drain port 21 may be provided in the vicinity of the cake outlet 14.
[0043]
The support target of the stand 1 may be the main case 6 or both the upper case 7 and the main case 6. Instead of the opening amount adjusting valve 24, a gate mechanism for closing the opening of the cylindrical case 8a may be provided, and the gate body may be closed and biased by a spring or a fluid pressure cylinder. The filtration screen 10 does not necessarily need to use a wedge wire as a filtration element, and may be formed by stacking a punching metal or a plurality of types of filtration elements inside and outside.
[Brief description of the drawings]
[Fig. 1] Vertical side view of the screw dehydrator on the inlet chamber side [Fig. 2] Schematic vertical side view of the screw dehydrator [Fig. 3] Overall side view of the screw dehydrator [Fig. 4] FIG. 5 is a sectional view taken along line AA in FIG. 4. FIG. 6 is a sectional view taken along line BB in FIG.
2 Outer shell case 4 Drive mechanism 5 Pump 9 Squeeze screw 10 Filtration screen 14 Cake outlet 17 Inlet chamber 18 Inlet pressure sensor 19 Outlet pressure sensor 21 Drain outlet 24 Opening adjustment valve 25 Outlet chamber 29/30 Rotating ring 35 Screen shaft 36 Motor 42 Ultrasonic oscillator 47 Control device

Claims

A compression screw (9) having a main shaft (26) that is suspended and rotated vertically and a helical blade (27) fixed to the outer peripheral surface of the main shaft (26), and an outer periphery of the compression screw (9) A cylindrical filtration screen (10), a vertically long outer shell case (2) that surrounds the periphery of the filtration screen (10) and is vertically supported, and an upper portion of the outer shell case (2) are used for filtering stock solution. An inlet chamber (17) to be introduced, and an outlet chamber (25) at the end of conveyance of the pressing screw (9) having a cake outlet (14) for discharging the dehydrated cake located at the lower end of the outer shell case (2). The entire machine equipped with is a vertically long screw dehydrator,
A pump (5) for continuously feeding the filtrate stock solution to the inlet chamber (17) during the dehydration operation,
Before dewatering with the pressing screw (9), the pressure of the filtrate solution in the inlet chamber (17) is maintained substantially equal to the supply pressure of the pump (5), thereby dewatering with the pressing screw (9). The previous filtration stock solution is pre-filtered by a filtration screen (10) on the side of the space surrounded by the uppermost surface of the spiral blade (27) and the inlet chamber (17),
An inlet pressure sensor (18) for detecting the pressure of the filtrate concentrate is arranged facing the inlet chamber (17), and faces the outlet chamber (25). The cake outlet (14) and the opening amount of the cake outlet (14) An opening amount adjusting valve (24) for adjusting the pressure and an outlet pressure sensor (19) are provided,
The operating state of the pump (5) is controlled based on the output signal from the inlet pressure sensor (18), and the opening amount of the opening adjustment valve (24) is controlled based on the output signal from the outlet pressure sensor (19). Control device (47)
The control device (47) compares the detected pressure of the inlet chamber (17) detected by the inlet pressure sensor (18) with a preset set pressure, and when the detected pressure exceeds the set pressure, the pump (5) When the feed amount is decreased and the detected pressure becomes less than the set pressure, control is performed to increase the feed amount of the pump (5).
In addition, the control device (47) compares the detected pressure of the outlet chamber (25) detected by the outlet pressure sensor (19) with a preset pressure, and adjusts the opening when the detected pressure exceeds the preset pressure. The opening amount of the valve (24) is increased, and when the detected pressure is lower than the set pressure, the opening amount of the opening amount adjusting valve (24) is controlled to decrease.
The set pressure that is the comparison target of the detected pressure by the outlet pressure sensor (19) and that is the reference for the increase / decrease control of the opening amount adjustment valve (24) is the comparison target of the detected pressure by the inlet pressure sensor (18) , and the and the pump (5) screw dehydrator characterized that you have been set larger than the reference become set pressure of the feed amount of the increase or decrease control.

A filtrate drainage port (21) is provided in the upper part of the outer shell case (2), and the outer shell case (2) below the filtrate liquid level (L) defined by the drainage port (21). A plurality of ultrasonic oscillators (42) that oscillate ultrasonic vibrations are arranged in a straight line in a state of being adjacent to each other in the vertical direction in a state of facing the filtration screen (10),
The screw dehydrator according to claim 1, wherein the filtration screen (10) can be driven to rotate at a low speed by a drive mechanism (4) provided on the outer surface of the machine body.

Rotating rings (29, 30) provided at the upper and lower ends of the filtration screen (10) can be freely rotated via bearings (31) provided between the outer shell case (2) and the rotating rings (29, 30). Supported,
The drive mechanism (4) includes a motor (36), a screen shaft (35) fixed to the lower end of the filtration screen (10), and a winding transmission mechanism that transmits motor power to the screen shaft (35). The screw dehydrator according to claim 2.