JP2004008901A

JP2004008901A - Drug injection control device

Info

Publication number: JP2004008901A
Application number: JP2002164817A
Authority: JP
Inventors: Naoya Kawarabayashi; 河原林　直也
Original assignee: Kurita Water Industries Ltd
Current assignee: Kurita Water Industries Ltd
Priority date: 2002-06-05
Filing date: 2002-06-05
Publication date: 2004-01-15
Anticipated expiration: 2022-06-05
Also published as: JP3941595B2

Abstract

【課題】被処理水側の急激な水質変動に迅速に対応可能な薬剤の注入制御を可能にし、処理水の水質の安定化を図った薬剤注入制御装置を提供すること。
【解決手段】被処理水（原水）に薬剤（ＰＡＣ、無機凝集剤、高分子凝集剤）を注入する薬剤注入手段（凝集剤貯槽４、注入ポンプ６、８）を備えて薬剤注入をする水処理システムにおける薬剤の注入量を制御する薬剤注入制御装置である。液質計測手段（濁度計２２）、演算手段（２５）、演算結果保持手段（２７）、補正量演算手段（２９）及び出力手段（３１）を含んで構成され、薬剤注入後の処理水の液質の計測結果に基づき、薬剤の注入量を演算し、その演算結果を所定時間（保持時間ＴＳ）保持し、その注入量を計測結果により補正している。この結果、被処理水側の急激な水質変動に迅速に対応可能な薬注制御が可能となり、処理水の水質の安定化を図ることができる。
【選択図】　　　　図１An object of the present invention is to provide a chemical injection control device capable of controlling injection of chemicals capable of promptly responding to rapid fluctuations in water quality on the treated water side and stabilizing the quality of treated water.
SOLUTION: Water for injecting a drug is provided with a drug injecting means (coagulant storage tank 4, injection pumps 6, 8) for injecting a drug (PAC, inorganic coagulant, polymer coagulant) into water to be treated (raw water). It is a medicine injection control device for controlling an injection amount of a medicine in a processing system. It comprises liquid quality measurement means (turbidity meter 22), calculation means (25), calculation result holding means (27), correction amount calculation means (29) and output means (31), and the treated water after chemical injection Based on the measurement result of the liquid quality, the injection amount of the medicine is calculated, the calculation result is held for a predetermined time (holding time TS), and the injection amount is corrected based on the measurement result. As a result, it is possible to perform chemical injection control capable of promptly responding to a sudden change in water quality on the treated water side, and to stabilize the quality of treated water.
[Selection diagram] Fig. 1

Description

【０００１】
【発明の属する技術分野】
本発明は、被処理水に薬剤を注入するときに薬剤注入量を制御する装置に関する。特に、濁質（ＳＳ）を含有した排水等を凝集剤により固液分離する等の薬注処理を含む水処理システムの薬剤注入制御装置に係り、詳しくは処理水の濁度に応じて凝集剤等の薬剤の注入量を制御して処理水の安定化を実現する薬剤注入制御装置に関する。
【０００２】
【従来の技術】
従来、排水の凝集処理には、塩化アルミニウム、ポリ塩化アルミニウム、硫酸アルミニウム、塩化第二鉄、ポリ硫酸第二鉄等の無機系凝集剤や高分子凝集剤が用いられ、被処理水に添加する凝集剤は一定量とされてきた。このため、排水流量、濁度、その他水質に変動があった場合には、手作業で凝集剤の添加率を調整しない限りは、凝集剤過剰や凝集剤不足となり、処理水の水質悪化等を生じていた。
【０００３】
このような不都合を回避する対策として、特公平７−２９１０１号「無機系排水の凝集処理装置」が提案されている。この装置は、排水流量及び濁度の検出値を積算して総濁質負荷を算出し、予め想定した濁質負荷と凝集剤薬注量との関係を求める関係式を用いて凝集剤の添加率を演算し、薬注量の自動制御をしている。単一の制御式では被処理水の質の変動に既存の薬注制御方式で対応できず、手作業によって手直しが余儀なくされる等の問題がある。
【０００４】
また、処理水濁度、原水流量及び原水濁度値を用いたフィードフォワード制御を用いた浄水処理等を対象とする排水処理として、例えば、特開昭５８−４０１１４号「水処理における凝集剤注入制御装置」が提案されている。原水側に設置される濁度計に原水による汚れが付着すると、制御不能に陥ることや、流量計が高価であることに加え、排水系においては、無機凝集剤の必要量を決定する因子中、流量が占める割合が低く、換言すれば、濁度やアルカリ度等、流量以外の因子が占める割合が高く、フィードフォワード制御が困難になるという問題があった。
【０００５】
このため、処理水の濁度によって凝集剤の注入量を制御するフィードバック制御が用いられているが、このフィードバック制御では、処理系の遅れ時間に起因する濁度出力の変動（振幅変化）を抑制するため、処理系の遅れ時間分の保持時間で制御時間を繰り返すサンプル値制御が用いられる。
【０００６】
【発明が解決しようとする課題】
ところで、凝集剤の注入量が保持時間で一定値となるサンプル値制御では、その保持時間中に急な水質変動が生じても、その変動に対応できないか、対応したとしても初期動作が遅延し、その結果、被処理水側の水質変動が処理水の濁度に現れ、処理水の水質の不安定、即ち、濁度が不安定になるという不都合があった。
【０００７】
そこで、本発明は、被処理水側の急激な水質変動に迅速に対応可能な薬剤の注入制御を可能にし、処理水の水質の安定化を図った薬剤注入制御装置を提供することを課題とする。
【０００８】
【課題を解決するための手段】
係る課題を解決した手段としての本発明の構成を実施の形態で用いた符号を付して列挙すれば、次の通りである。
【０００９】
請求項１に係る本発明の薬剤注入制御装置は、被処理水（原水）に薬剤（ＰＡＣ、無機凝集剤、高分子凝集剤）を注入する薬剤注入手段（凝集剤貯槽４、注入ポンプ６、８）を備えて薬剤注入をする水処理システムにおける薬剤の注入量を制御する薬剤注入制御装置であって、薬剤注入後の処理水の液質を計測する液質計測手段（濁度計２２）と、この液質計測手段の計測結果に基づき、前記被処理水に対する薬剤の注入量を演算する演算手段（注入量演算手段２５）と、この演算手段で得られた演算結果を所定時間（保持時間ＴＳ）保持する演算結果保持手段（２７）と、前記液質計測手段の計測結果に基づき、前記注入量の補正量を算出する補正量演算手段（２９）と、前記演算結果保持手段に保持されている前記注入量を前記補正量演算手段で得られる補正量で補正し、その結果を用いて薬剤の注入量を出力する出力手段（３１）とを備えたことを特徴とする。ここで、薬剤の注入量とは、注入量及びその制御に用いる中間値の何れも含むものである。
【００１０】
請求項２に係る本発明の薬剤注入制御装置は、被処理水に凝集剤を注入する凝集剤注入手段を備えて凝集剤注入後の被処理水を固液分離する水処理システムにおける凝集剤の注入量を制御する薬剤注入制御装置であって、前記固液分離後の処理水の液質を計測する液質計測手段と、この液質計測手段の計測結果に基づき、前記凝集剤注入手段における注入量を演算する演算手段と、この演算手段によって得られる演算結果を所定時間保持する演算結果保持手段と、前記液質計測手段の計測結果に基づき、前記注入量の補正量を算出する補正量演算手段と、前記演算結果保持手段で保持されている前記注入量を前記補正量演算手段で得られる補正量で補正し、その結果を用いて凝集剤の注入量を出力する出力手段とを備えたことを特徴とする。
【００１１】
請求項３に係る本発明の薬剤注入制御装置は、請求項１又は２記載の薬剤注入制御装置において、前記補正量演算手段が予め設定される液質の目標値と前記液質計測手段から得られる計測結果の差を補正量とすることを特徴とする。
【００１２】
請求項４に係る本発明の薬剤注入制御装置は、請求項１又は２記載の薬剤注入制御装置において、前記補正量演算手段が予め設定される液質計測結果の上限値及び／又は下限値と前記液質計測手段から得られる計測結果を比較し、計測値が上限値を超えた場合、又は、下限値を下回った場合に、所定の薬注増量又は所定の薬注減量を補正量とすることを特徴とする。
【００１３】
請求項５に係る本発明の薬剤注入制御装置は、請求項１又は２記載の薬剤注入制御装置において、前記補正量演算手段が予め設定される液質計測結果の上限値及び／又は下限値と前記液質計測手段から得られる計測結果を比較し、計測値が上限値を超えた場合、又は、下限値を下回った場合に、所定の薬注増量又は所定の薬注減量とし、これら薬注増量又は薬注減量の少なくとも一方を予め設定される液質の目標値と前記液質計測手段から得られる計測結果の差を用いて算出した結果を補正量とすることを特徴とする。
【００１４】
このような水処理システムの薬剤注入制御装置は、シックナ、クライファイヤ、横流式沈澱池、加圧浮上装置等、無機凝集剤、高分子凝集剤等を使用する各種の固液分離装置、その他の水処理装置を対象とし、処理系で発生するサンプル値ＰＩ制御が持つ処理の安定化とともに、凝集剤等の薬剤注入の最適化を実現し、処理水の液質の安定化を実現できる。
【００１５】
【発明の実施の形態】
本発明の薬剤注入制御装置は、例えば、図１に示す実施の形態のように構成することができる。
【００１６】
薬剤反応槽としての凝集反応槽２は、排水等の被処理水である原水と、注入薬剤としての凝集剤とを反応させる手段である。この凝集反応槽２に対して凝集剤注入手段として凝集剤を貯める凝集剤貯槽４、注入ポンプ６、８等が備えられ、この実施の形態では、凝集剤貯槽４には無機凝集剤としてポリ塩化アルミニウム（ＰＡＣ）を貯めたＰＡＣ貯槽１０、高分子凝集剤を貯めた高分子貯槽１２が設置されている。凝集反応槽２には、ＰＡＣ貯槽１０から無機凝集剤としてＰＡＣが注入ポンプ６により、高分子貯槽１２から高分子凝集剤が注入ポンプ８により連続的又は断続的に注入される。各注入ポンプ６、８はインバータ１４、１６の各出力によって駆動される。
【００１７】
また、凝集反応槽２の下流側には、固液分離手段として固液分離槽１８、濁質が分離された処理水を貯める処理水槽２０が設置されている。処理水槽２０には、処理水の液質を計測する液質計測手段として、濁度（ＳＳ）を計測する濁度計２２が設置されており、この濁度計２２の計測値（濁度）が演算及び制御手段としてのコントローラ２４に加えられている。
【００１８】
このコントローラ２４には、ディジタル演算処理又はアナログ演算処理等を行うコンピュータが用いられ、図示しないが、演算・制御手段としてのプロセッサ、記憶手段としてのＲＯＭ、ＲＡＭ、外部記憶手段としてのＭＯ、ハードディスク装置の他、入出力手段（Ｉ／Ｏ）等も備えられている。ＲＯＭには、演算プログラムや薬注制御プログラム等の各種のプログラムや固定データ等が格納されている。また、ＲＡＭには、演算途上のデータや制御履歴等が格納される。そして、このコントローラ２４は演算処理によって制御出力を発生し、この制御出力が各インバータ１４、１６に加えられ、注入ポンプ６、８が制御される。
【００１９】
そこで、このコントローラ２４の演算及び制御処理を中心に機能的に表せば、例えば、図２に示すように、コントローラ２４には、薬剤の注入量演算手段２５、演算結果保持手段２７、補正量演算手段２９、出力手段３１等を備えている。注入量演算手段２５は、液質計測手段である濁度計２２の計測結果、即ち、濁度計測値３３に基づき、被処理水に対する薬剤の注入量を演算し、演算結果保持手段２７は、注入量演算手段２５で得られた演算結果を所定時間保持し、また、補正量演算手段２９は、濁度計測値３３に基づき、薬剤の注入量の補正量を算出する。ここで、補正量としては、例えば、上限値及び下限値を設定し、上限値＜計測値のとき＋ｘ、下限値＞計測値のとき−ｙとすればよく、また、例えば、補正量＝（計測値−目標値）×ｋ（係数）としてもよい。そして、出力手段３１は、演算結果保持手段２７に保持されている保持データである注入量Ｄ１を補正量演算手段２９で得られる補正量Ｄ２で補正し、その結果を用いて薬剤の注入量を出力する。この出力は、制御出力としてインバータ１４、１６に加えられている。
【００２０】
そして、このような演算及び制御処理機能を実現するコントローラ２４を具体的に説明すれば、例えば、図３に示すように、濁度計２２からの計測値を取り込む検出部２６、その濁度を用いて凝集剤の注入量やその修正量を演算する演算部２８、濁度等の注入制御量や注入量を所定の時間間隔（タイミング）で保持するサンプル・ホールド部３０、演算部２８で算出された注入量や修正量に基づく制御出力を発生する制御出力部３２、サンプル・ホールド部３０及び制御出力部３２等に所定のタイミング信号を付与するタイミング制御部３４等を備えた構成とすることができる。
【００２１】
この薬剤注入制御動作を説明すると、原水が導入された凝集反応槽２にＰＡＣ貯槽１０から注入ポンプ６によってＰＡＣ、高分子貯槽１２から注入ポンプ８によって高分子凝集剤が注入される。各凝集剤及び原水は凝集反応槽２内で攪拌された後、固液分離槽１８に流れる。凝集剤によって原水には凝集フロックが形成されるが、固液分離槽１８では固体物と処理水とに分離され、固体物はスラッジとして排出され、また、処理水は処理水槽２０に導かれる。処理水槽２０では、処理水の状態が濁度計２２によって計測され、処理水の濁度が凝集剤の制御情報としてコントローラ２４に加えられる。
【００２２】
このコントローラ２４による薬注制御では、例えば、図４に示すように、濁度に応じたサンプル値ＰＩ制御と、水質の急変に対応する修正制御ｆ（ｘ）とが併用される。
【００２３】
コントローラ２４の演算処理では、予め定められた処理水の濁度の目標値に対する濁度の偏差を演算処理によって認識し、サンプル値Ｐ（比例）Ｉ（積分）制御により、処理水の濁度が目標値へ近づくように最適な凝集剤の注入量が演算され、それを表す信号がインバータ１４に加えられ、その出力によって注入ポンプ６が駆動される。このような処理は、注入ポンプ８側でも同様である。
【００２４】
ところで、サンプル値ＰＩ制御は、例えば、凝集反応槽２から処理水槽２０に至る処理系での時間遅れによる制御の行き過ぎによって処理水槽２０側に生じる濁度変化（振幅）を防止するために、数十秒の制御動作後、その効果が処理水の濁度に現れるまでの遅れ時間だけ保持時間を設定し、無機凝集剤の制御をホールドすることを繰り返すアドバンスドＰＩＤ制御の一種である。
【００２５】
この場合、処理水の水質、即ち、濁度のみで凝集剤の注入量をフィードバック制御した場合、水質の急変による初期対応の遅延を回避するには、制御量の保持時間を短縮すればよいが、系内の遅れ時間ＴＤより保持時間を短縮すると、制御出力が振幅傾向となり、保持時間の短縮が処理の不安定化要因になる。
【００２６】
そこで、系内の遅れ時間ＴＤと同一又は遅れ時間ＴＤより長い保持時間を持つサンプル値ＰＩ制御を維持しながら、その保持時間中であっても、濁度の急変に対応する値を加算し、サンプル値ＰＩ制御の制御出力量を修正し、サンプル値ＰＩ制御を補完するものである。即ち、サンプル値ＰＩ制御によって無機凝集剤の出力注入量が求められるが、この注入量とは別に、検出した処理水の濁度（ＰＶ）値（％）と、目標（ＳＰ）値（％）との偏差（ＤＶ）値（％）を求める。即ち、偏差（ＤＶ）値（％）は、
偏差（ＤＶ）値（％）＝濁度（ＰＶ）値（％）−目標（ＳＰ）値（％）・・・（１）
で求められる。この偏差値（ＤＶ値）（＝ＰＶ−ＳＰ）に比例する値を出力注入量に加算すれば、処理水の水質が急変したとき、サンプル値ＰＩ制御の保持時間内であっても、その水質の急変に対応した薬注制御を行うことができ、水質の安定化を図ることができる。
【００２７】
このような制御では、例えば、図５の（Ａ）に示すように、凝集反応槽２に流れ込む原水に水質変化が生じ、濁度計２２には、例えば、図５の（Ｂ）に示すように、処理水の濁度が検出されたとし、ＴＤを系の遅れ時間、ＴＳをサンプリングの時間間隔に設定する。この実施の形態では、ＴＤ＝ＴＳとしている。
【００２８】
濁度（ＰＶ）値は時間間隔ＴＳ毎の値が演算情報となり、その濁度変化に応じたサンプル値ＰＩ制御の制御出力量が演算され、例えば、図５の（Ｃ）に実線で示すように、所定の時間間隔ＴＳで一定値に保持された凝集剤注入量ＭＶ_１が得られる。
【００２９】
そして、図５の（Ｂ）に示すように、目標（ＳＰ）値が設定されると、この目標（ＳＰ）値を演算情報とし、式（１）から、濁度（ＰＶ）値との偏差（ＤＶ）値が演算される。この偏差（ＤＶ）値（＝ＰＶ−ＳＰ）に比例する凝集剤注入量ＭＶ_２が演算される。この凝集剤注入量ＭＶ_２は、サンプル値ＰＩ制御で求められた凝集剤注入量ＭＶ_１に加算され、凝集剤注入量ＭＶは、
ＭＶ＝ＭＶ_１＋ＭＶ_２　　　　　　　　　・・・・（２）
となる。このような凝集剤注入量とすれば、処理水の水質が急変したとき、サンプル値ＰＩ制御の保持時間内であっても、その水質の急変に対応した薬注制御を行うことができ、水質の安定化を図ることができる。
【００３０】
ところで、凝集剤の注入量、即ち、必要添加量（ｇ／Ｌ）は、
ａ　排水の流量（Ｌ／Ｈｒ）
ｂ　排水のＳＳ濃度（ｇ／Ｌ）
ｃ　それ以外の因子（ｇ／ｇ）
によって決まる。ｃは、ａ、ｂ以外の要因を総括したパラメータであるから、凝集剤の必要注入量（ｇ／Ｈｒ）は、

で与えられる。即ち、この必要注入量（ｇ／Ｈｒ）は、ｄｒｙＳＳ＝１ｇ当たりの必要薬注率（ｇ／ｇ）で表すことができる。
【００３１】
また、この実施の形態では、例えば、図６に示すフローチャートに従って薬注制御を行う。即ち、流量負荷が高い場合、無機凝集剤を増加させても、高分子凝集剤の注入量が不足する（フロック沈降速度の低下）と、凝集したフロック自体が処理水側にキャリーオーバーし、処理水の濁度が改善されない場合がある。そこで、ステップＳ１では、図４に示す薬注制御により、無機凝集剤の注入量を増加し、ステップＳ２では、処理水の濁度が改善されたか否かを濁度計２２の計測値から判定する。この場合、濁度が改善されているときには、ステップＳ３に移行し、無機凝集剤の注入制御を続行する。
【００３２】
また、無機凝集剤の注入によって処理水の濁度が改善されていない場合には、ステップＳ４に移行し、その濁度に応じて高分子凝集剤の注入制御を行い、ステップＳ２に戻る。高分子凝集剤の注入制御は、インバータ１６を通して注入ポンプ８を駆動して高分子貯槽１２から高分子凝集剤を凝集反応槽２に注入し、その制御は既に述べた図４のサンプル値ＰＩ制御及び修正制御を実行する。この場合、高分子凝集剤の注入率も処理水の濁度の出力値に応じて多段階に注入量を制御することで、排水の流量、水質の変動に対して対応幅の拡大が可能となる。
【００３３】
このような高分子凝集剤の注入制御を併用すれば、処理水の濁度によるＰＡＣのフィードバック制御の実施では、処理水の濁度が改善できないとき、即ち、濁度が一定値を超えたとき、高分子凝集剤の不足（フロックの沈降速度の低下）であると認識し、高分子凝集剤の注入量を増加させ、その結果、自動制御によるＰＡＣ等の無機凝集剤の過剰添加を防止することができる。
【００３４】
また、本発明の薬剤注入制御装置は、図１に示した実施の形態のコントローラ２４を例えば、図７に示す実施の形態のように構成してもよい。この実施の形態では、コントローラ２４に限界値設定部３８を設けることにより、処理水の濁度の測定（ＰＶ）値に上限値ＳＰＨ、下限値ＳＰＬの何れか一方又は双方を設定し、これらの限界値を演算情報に用いて例えば、図８に示す薬注制御を行うようにしたものである。この場合、上限値ＳＰＨは、サンプル値ＰＩ制御の目標（ＳＰ）値より大きな値とし、下限値ＳＰＬは、サンプル値ＰＩ制御の目標（ＳＰ）値より小さな値とする。
【００３５】
第１の実施形態で述べたように、サンプル値ＰＩ制御を実行中に、処理水の濁度が上限値ＳＰＨを超えた場合、薬注出力値（＝ＭＶ）に一定量（α）を加算し、また、処理水の濁度が下限値ＳＰＬを下回った場合には、薬注出力（ＭＶ）値に一定量（β）を減算し、薬注出力（ＭＶ）値を修正する。この場合、薬注出力（ＭＶ）値に加算又は減算する値は、一定量に代え、濁度変化に応じた値、上限値ＳＰＨを超える値又は下限値ＳＰＬを下回る値に応じて求めた変動値ｆ（α）、ｇ（β）としてもよい。
【００３６】
図９の（Ａ）〜（Ｃ）は、この制御の一例であり、（Ａ）は原水の濁度変化、（Ｂ）は測定（ＰＶ）値、（Ｃ）は薬注出力（ＭＶ）値を示し、ＴＤは系の遅れ時間、ＴＳはサンプリングの時間間隔である。測定（ＰＶ）値には、目標（ＳＰ）値に対し、上限値ＳＰＨ、下限値ＳＰＬが設定されている。この場合、測定値が上限値ＳＰＨを超えたとき、サンプル値ＰＩ制御で求められた凝集剤注入量ＭＶ_１に一定値の注入量ＭＶ_２が加算され、また、測定値の下限値ＳＰＬを下回ったとき、凝集剤注入量ＭＶ_１に一定値の注入量ＭＶ_２が減算される。これを式で示すと、次の通りである。
ＭＶ＝ＭＶ_１＋ＭＶ_２　　　　　　　　　・・・・（４）
ＭＶ＝ＭＶ_１−ＭＶ_２　　　　　　　　　・・・・（５）
【００３７】
従って、このような凝集剤注入量とすれば、処理水の水質が急変したとき、サンプル値ＰＩ制御の保持時間内であっても、その水質の急変に対応した薬注制御を行うことができ、水質の安定化を図ることができる。
【００３８】
このような制御を施した場合においても、流量負荷が高いと、無機凝集剤を増加させても、高分子凝集剤の注入量が不足する（フロックの沈降速度の低下）と、凝集したフロック自体が処理水側にキャリーオーバーし、処理水濁度が改善されないとき、図６のフローチャートに示した高分子凝集剤の注入制御を併用すればよく、同様に、ＰＡＣ等の無機凝集剤の過剰注入を防止できる。
【００３９】
なお、図５及び図９に示す実施の形態では、サンプル・ホールド処理による測定値ＰＶの保持時間ＴＳを系の遅れ時間ＴＤと同等（ＴＳ＝ＴＤ）に設定しているが、ＴＳ＞ＴＤとしてもよい。
【００４０】
また、前記実施の形態では、被処理水である原水に注入すべき薬剤をＰＡＣや高分子薬剤を例にとって説明したが、本発明は、被処理水に酸やアルカリ等の薬剤を注入する等、各種の薬剤の注入制御を包含するものであり、凝集剤注入に限定されるものではない。
【００４１】
また、前記実施の形態では、コントローラ２４を薬剤注入制御装置として説明したが、本発明は、被処理水である原水を入力、処理水を出力にし、実施の形態で述べた水処理システムを薬剤注入制御装置として捉えてもよく、実施の形態に開示した発明には次に列挙する技術的思想を包含するものである。
【００４２】
即ち、凝集剤の添加によって被処理水の固液分離を行う水処理システムの薬剤注入制御装置としては、被処理水（原水）に凝集剤（ＰＡＣ、無機凝集剤、高分子凝集剤）を注入する凝集剤注入手段（凝集剤貯槽４、注入ポンプ６、８）と、前記凝集剤の注入による固液分離後の処理水の濁度を検出する濁度検出手段（濁度計２２）と、この濁度検出手段の検出濁度を用いて凝集剤の注入量を演算し、その注入量を所定時間（保持時間ＴＳ）だけ保持するとともに、その保持時間中の濁度変化により前記注入量を修正する制御手段（コントローラ２４）とを備えるように構成してもよい。同様に、処理水の液質を安定化させることができる。
【００４３】
また、この水処理システムの薬剤注入制御装置において、前記保持時間には、処理系の時間遅れに対応した時間を用いてもよい。
【００４４】
また、この水処理システムの薬剤注入制御装置において、前記注入量の保持時間（ＴＳ）中の濁度を検出し、その濁度と目標値との偏差を演算し、その偏差に応じて前記注入量を修正するようにしてもよい。
【００４５】
また、この水処理システムの薬剤注入制御装置において、前記注入量の保持時間中の濁度が所定の上限値（ＳＰＨ）を超え、又は下限値（ＳＰＬ）を下回ったとき、前記注入量に対して一定値又は濁度変化に応じた値を加算又は減算するようにしてもよい。
【００４６】
また、この水処理システムの薬剤注入制御装置において、前記濁度の上限値は前記目標値を超える値、前記濁度の下限値は前記目標値を下回る値を用いてもよい。
【００４７】
また、この水処理システムの薬剤注入制御装置において、前記被処理水に対する無機凝集剤の注入量を増加させても、前記濁度検出手段の検出濁度に変化が生じないとき、前記凝集剤注入手段から高分子凝集剤を前記被処理水に注入するようにしてもよい。
【００４８】
【発明の効果】
以上説明したように、本発明によれば、次の効果が得られる。
ａ　被処理水側の急激な水質変動に迅速に対応可能な薬注制御を可能にし、処理水の水質の安定化を図ることができる。
ｂ　フィードフォワード制御が困難な排水系等に用いても、凝集反応槽における時間遅れ等の影響を受け難く、且つ急激な水質の変動にも対応して処理水の濁度の安定化、水質の安定化を図ることができる。
ｃ　処理水の濁度値によるフィードバック制御のみで、初期応答の遅れを解消でき、処理水の水質を安定化を図ることができる。
【図面の簡単な説明】
【図１】本発明の薬剤注入制御装置の第１の実施形態を示すブロック図である。
【図２】コントローラの機能及び構成を示すブロック図である。
【図３】コントローラの構成を示すブロック図である。
【図４】本発明の薬剤注入制御装置の第１の実施形態における薬注制御を示すフローチャートである。
【図５】本発明の第１の実施形態における薬注制御タイミングを示す図である。
【図６】高分子凝集剤を併用する薬注制御を示すフローチャートである。
【図７】本発明の薬剤注入制御装置の第２の実施形態に係るコントローラの構成を示すブロック図である。
【図８】本発明の薬剤注入制御装置の第２の実施形態における薬注制御を示すフローチャートである。
【図９】本発明の第２の実施形態における薬注制御タイミングを示す図である。
【符号の説明】
４　凝集剤貯槽（薬剤注入手段）
６、８　注入ポンプ（薬剤注入手段）
２２　濁度計（液質計測手段）
２４　コントローラ（制御手段）
２５　注入量演算手段
２７　演算結果保持手段
２９　補正量演算手段
３１　出力手段[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a device for controlling a drug injection amount when a drug is injected into water to be treated. In particular, the present invention relates to a chemical injection control device for a water treatment system including a chemical injection process such as solid-liquid separation of wastewater containing turbidity (SS) using a coagulant, and more particularly, to a coagulant according to the turbidity of treated water. The present invention relates to a drug injection control device that controls the injection amount of a drug or the like to stabilize treated water.
[0002]
[Prior art]
Conventionally, in the coagulation treatment of wastewater, an inorganic coagulant or a polymer coagulant such as aluminum chloride, polyaluminum chloride, aluminum sulfate, ferric chloride, and ferric polysulfate are used and added to the water to be treated. Flocculants have been used in fixed amounts. For this reason, if there is a change in the flow rate of effluent water, turbidity, or other water quality, the coagulant becomes excessive or insufficient, unless the addition rate of the coagulant is manually adjusted. Had occurred.
[0003]
As a countermeasure to avoid such inconvenience, Japanese Patent Publication No. 7-29101, "Inorganic wastewater coagulation treatment apparatus" has been proposed. This device calculates the total turbidity load by integrating the detected values of the wastewater flow rate and the turbidity, and adds the flocculant using a relational expression that calculates the relationship between the presumed turbidity load and the coagulant drug injection amount. The rate is calculated, and the amount of chemical injection is controlled automatically. A single control method cannot cope with fluctuations in the quality of the water to be treated by the existing chemical injection control method, and there is a problem that manual adjustment is required.
[0004]
Further, as wastewater treatment for water purification treatment using feedforward control using treated water turbidity, raw water flow rate, and raw water turbidity value, for example, JP-A-58-40114, “Coagulant injection in water treatment” A control device "has been proposed. If dirt from the raw water adheres to the turbidity meter installed on the raw water side, it becomes uncontrollable, the flowmeter is expensive, and in the drainage system, factors that determine the required amount of inorganic coagulant However, the ratio occupied by the flow rate is low, in other words, the ratio occupied by factors other than the flow rate, such as turbidity and alkalinity, is high, and there has been a problem that feedforward control becomes difficult.
[0005]
For this reason, feedback control that controls the amount of coagulant injected based on the turbidity of the treated water is used. In this feedback control, fluctuations (amplitude changes) in the turbidity output due to the delay time of the processing system are suppressed. Therefore, sample value control in which the control time is repeated with the holding time for the delay time of the processing system is used.
[0006]
[Problems to be solved by the invention]
By the way, in the sample value control in which the injection amount of the coagulant becomes a constant value during the holding time, even if a sudden change in water quality occurs during the holding time, the fluctuation cannot be dealt with or the initial operation is delayed even if it is handled. As a result, fluctuations in the water quality of the water to be treated appear in the turbidity of the treated water, and the water quality of the treated water becomes unstable, that is, the turbidity becomes unstable.
[0007]
Therefore, an object of the present invention is to provide a drug injection control device which enables injection control of a drug capable of promptly responding to a rapid change in water quality on the treated water side and stabilizes the quality of treated water. I do.
[0008]
[Means for Solving the Problems]
The configuration of the present invention as a means for solving such a problem is given as follows with reference to the reference numerals used in the embodiments.
[0009]
The medicine injection control device of the present invention according to claim 1 is a medicine injection means (coagulant storage tank 4, injection pump 6, and injection pump 6) for injecting medicine (PAC, inorganic coagulant, polymer coagulant) into the water to be treated (raw water). 8) A drug injection control device for controlling the injection amount of a drug in a water treatment system for injecting a drug having 8), wherein a liquid quality measuring means (turbidity meter 22) for measuring the liquid quality of the treated water after the injection of the drug. Calculating means for calculating the amount of chemical to be injected into the water to be treated based on the result of measurement by the liquid quality measuring means (injection amount calculating means 25); and calculating the result obtained by the calculating means for a predetermined time (holding). Time TS) Calculation result holding means (27) for holding, correction amount calculation means (29) for calculating a correction amount of the injection amount based on the measurement result of the liquid quality measurement means, and holding in the calculation result holding means Of the injection amount that has been Corrected by the correction amount obtained by the means, characterized in that an output means (31) for outputting the injection amount of the agent using the results. Here, the injection amount of the medicine includes both the injection amount and an intermediate value used for controlling the injection amount.
[0010]
The chemical injection control device of the present invention according to claim 2 comprises a coagulant injection means for injecting the coagulant into the water to be treated, the coagulant in a water treatment system for solid-liquid separation of the water to be treated after the coagulant injection. A drug injection control device that controls an injection amount, wherein a liquid quality measurement unit that measures the liquid quality of the treated water after the solid-liquid separation, and a coagulant injection unit based on a measurement result of the liquid quality measurement unit. Calculation means for calculating the injection amount, calculation result holding means for holding the calculation result obtained by the calculation means for a predetermined time, and a correction amount for calculating the correction amount of the injection amount based on the measurement result of the liquid quality measurement means Calculating means, and output means for correcting the injection amount held by the calculation result holding means with a correction amount obtained by the correction amount calculating means, and outputting the injection amount of the coagulant using the result. It is characterized by having.
[0011]
According to a third aspect of the present invention, there is provided the drug injection control device according to the first or second aspect, wherein the correction amount calculating means obtains from a preset liquid quality target value and the liquid quality measuring means. The difference between the measurement results obtained is used as a correction amount.
[0012]
According to a fourth aspect of the present invention, there is provided the drug injection control device according to the first or second aspect, wherein the correction amount calculating means sets an upper limit value and / or a lower limit value of a liquid quality measurement result set in advance. Compare the measurement results obtained from the liquid quality measurement means, if the measured value exceeds the upper limit, or, if less than the lower limit, the predetermined amount of injection or reduction of the predetermined injection is a correction amount. It is characterized by the following.
[0013]
According to a fifth aspect of the present invention, there is provided the drug injection control device according to the first or second aspect, wherein the correction amount calculating means sets an upper limit value and / or a lower limit value of a liquid quality measurement result set in advance. Compare the measurement results obtained from the liquid quality measurement means, if the measured value exceeds the upper limit, or if it is less than the lower limit, as a predetermined drug injection increase or predetermined drug injection reduction, these drug injection The correction amount is obtained by calculating at least one of the increase and the decrease in the amount of chemical injection using a difference between a preset target value of the liquid quality and a measurement result obtained from the liquid quality measuring means.
[0014]
Chemical injection control devices of such water treatment systems include thickeners, cryifiers, cross-flow settling basins, pressure flotation devices, various solid-liquid separation devices using inorganic coagulants, polymer coagulants, etc. For the water treatment apparatus, it is possible to stabilize the processing of sample value PI control generated in the processing system, optimize injection of a coagulant or the like, and stabilize the liquid quality of the treated water.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The drug injection control device of the present invention can be configured, for example, as in the embodiment shown in FIG.
[0016]
The coagulation reaction tank 2 as a chemical reaction tank is a means for reacting raw water, which is water to be treated such as waste water, with a coagulant as an injection medicine. The coagulation reaction tank 2 is provided with a coagulant storage tank 4 for storing a coagulant as coagulant injection means, injection pumps 6 and 8, and the like. A PAC storage tank 10 storing aluminum (PAC) and a polymer storage tank 12 storing a polymer flocculant are provided. PAC as an inorganic coagulant is injected from the PAC storage tank 10 into the coagulation reaction tank 2 by the injection pump 6, and a polymer coagulant is injected from the polymer storage tank 12 continuously or intermittently by the injection pump 8. Each infusion pump 6, 8 is driven by each output of

inverters

14, 16.
[0017]
On the downstream side of the coagulation reaction tank 2, a solid-liquid separation tank 18 as a solid-liquid separation means and a treated water tank 20 for storing treated water from which turbid matter has been separated are provided. In the treated water tank 20, a turbidity meter 22 for measuring turbidity (SS) is installed as a liquid quality measuring means for measuring the liquid quality of the treated water, and a measured value (turbidity) of the turbidity meter 22 is provided. Is added to the controller 24 as arithmetic and control means.
[0018]
As the controller 24, a computer for performing digital operation processing or analog operation processing is used. Although not shown, a processor as operation / control means, a ROM and a RAM as storage means, an MO as an external storage means, a hard disk drive In addition, input / output means (I / O) and the like are also provided. The ROM stores various programs such as an arithmetic program and a drug injection control program, fixed data, and the like. In addition, the RAM stores data being processed, control history, and the like. The controller 24 generates a control output through arithmetic processing, and the control output is applied to each of the

inverters

14 and 16 to control the infusion pumps 6 and 8.
[0019]
Therefore, functionally expressing the calculation and control processing of the controller 24 as a center, for example, as shown in FIG. 2, the controller 24 includes a medicine injection amount calculation unit 25, a calculation result holding unit 27, a correction amount calculation unit Means 29, output means 31 and the like. The injection amount calculation means 25 calculates the injection amount of the chemical into the water to be treated based on the measurement result of the turbidity meter 22 as the liquid quality measurement means, that is, the turbidity measurement value 33, and the calculation result holding means 27 The calculation result obtained by the injection amount calculation means 25 is held for a predetermined time, and the correction amount calculation means 29 calculates a correction amount of the injection amount of the medicine based on the turbidity measurement value 33. Here, as the correction amount, for example, an upper limit value and a lower limit value may be set, and the upper limit value may be set to + x when the measured value is smaller, and the lower limit value may be set to −y when the measured value is set. (Measured value−target value) × k (coefficient). Then, the output unit 31 corrects the injection amount D1 which is the data held in the calculation result holding unit 27 with the correction amount D2 obtained by the correction amount calculation unit 29, and uses the result to determine the injection amount of the medicine. Output. This output is applied to

inverters

14 and 16 as a control output.
[0020]
The controller 24 that realizes such calculation and control processing functions will be described in detail. For example, as shown in FIG. 3, a detection unit 26 that takes in a measurement value from the turbidimeter 22 A calculation unit 28 for calculating the injection amount of the coagulant and the correction amount thereof using the control unit; a sample and hold unit 30 for holding the injection control amount such as turbidity and the injection amount at predetermined time intervals (timing); A control output unit 32 for generating a control output based on the injected injection amount and the correction amount, a timing control unit 34 for giving a predetermined timing signal to the sample and hold unit 30, the control output unit 32, and the like. Can be.
[0021]
Describing this chemical injection control operation, PAC is injected from the PAC storage tank 10 by the injection pump 6 into the coagulation reaction tank 2 into which raw water is introduced, and a polymer flocculant is injected from the polymer storage tank 12 by the injection pump 8. After each flocculant and raw water are stirred in the flocculation reaction tank 2, they flow into the solid-liquid separation tank 18. The flocculant forms flocculated floc in the raw water, but is separated into solid matter and treated water in the solid-liquid separation tank 18, the solid matter is discharged as sludge, and the treated water is led to the treated water tank 20. In the treated water tank 20, the state of the treated water is measured by the turbidimeter 22, and the turbidity of the treated water is added to the controller 24 as control information of the flocculant.
[0022]
In the chemical injection control by the controller 24, for example, as shown in FIG. 4, a sample value PI control according to turbidity and a correction control f (x) corresponding to a sudden change in water quality are used in combination.
[0023]
In the arithmetic processing of the controller 24, a deviation of turbidity from a predetermined target value of the turbidity of the treated water is recognized by the arithmetic processing, and the turbidity of the treated water is controlled by the sample value P (proportional) I (integral) control. An optimum injection amount of the coagulant is calculated so as to approach the target value, a signal representing the calculated amount is added to the inverter 14, and the output thereof drives the injection pump 6. Such processing is the same on the infusion pump 8 side.
[0024]
The sample value PI control is performed, for example, in order to prevent a change in turbidity (amplitude) generated on the side of the treatment water tank 20 due to excessive control due to a time delay in the treatment system from the flocculation reaction tank 2 to the treatment water tank 20. This is a type of advanced PID control in which the holding time is set for a delay time until the effect appears in the turbidity of the treated water after the control operation for 10 seconds, and the control of the inorganic flocculant is repeated.
[0025]
In this case, when the quality of the treated water, that is, the injection amount of the flocculant is feedback-controlled only by the turbidity, in order to avoid a delay in the initial response due to a sudden change in the water quality, the holding time of the control amount may be reduced. If the holding time is shorter than the delay time TD in the system, the control output tends to have an amplitude, and the shortening of the holding time becomes a factor of destabilizing the processing.
[0026]
Therefore, while maintaining the sample value PI control having a holding time equal to or longer than the delay time TD in the system, even during the holding time, a value corresponding to a sudden change in turbidity is added, The control output amount of the sample value PI control is corrected to complement the sample value PI control. That is, the output injection amount of the inorganic coagulant is obtained by controlling the sample value PI. Apart from this injection amount, the detected turbidity (PV) value (%) of the treated water and the target (SP) value (%) (DV) value (%) is obtained. That is, the deviation (DV) value (%) is
Deviation (DV) value (%) = turbidity (PV) value (%) − target (SP) value (%) (1)
Is required. If a value proportional to this deviation value (DV value) (= PV-SP) is added to the output injection amount, when the water quality of the treated water changes suddenly, even if it is within the holding time of the sample value PI control, Control can be performed in response to sudden changes in the water quality, and water quality can be stabilized.
[0027]
In such control, for example, as shown in FIG. 5A, a change in water quality occurs in the raw water flowing into the coagulation reaction tank 2, and the turbidity meter 22 displays, for example, as shown in FIG. Then, assuming that the turbidity of the treated water is detected, TD is set to the system delay time, and TS is set to the sampling time interval. In this embodiment, TD = TS.
[0028]
As for the turbidity (PV) value, the value for each time interval TS becomes the calculation information, and the control output amount of the sample value PI control according to the turbidity change is calculated. For example, as shown by a solid line in FIG. , the coagulant injection amount MV ₁ held at a constant value at a predetermined time interval TS is obtained.
[0029]
Then, as shown in FIG. 5B, when the target (SP) value is set, the target (SP) value is used as calculation information, and the deviation from the turbidity (PV) value is calculated from Expression (1). (DV) value is calculated. The deviation (DV) values (= PV-SP) proportional to coagulant injection amount MV ₂ is calculated. The coagulant injection amount MV ₂ is added to the coagulant injection amount MV ₁ obtained by the sample values PI control, coagulant injection amount MV is
MV = MV ₁ + MV ₂ ... (2)
It becomes. With such a coagulant injection amount, when the water quality of the treated water changes suddenly, even during the holding time of the sample value PI control, it is possible to perform chemical injection control corresponding to the sudden change in the water quality. Can be stabilized.
[0030]
By the way, the injection amount of the flocculant, that is, the required addition amount (g / L) is
a Flow rate of wastewater (L / Hr)
b SS concentration of wastewater (g / L)
c Other factors (g / g)
Depends on Since c is a parameter summarizing factors other than a and b, the required injection amount (g / Hr) of the flocculant is

Given by That is, the required injection amount (g / Hr) can be expressed by drySS = 1 required injection rate per g (g / g).
[0031]
In this embodiment, for example, the medicine injection control is performed according to the flowchart shown in FIG. In other words, when the flow rate load is high, even if the amount of the inorganic flocculant is increased, if the injection amount of the polymer flocculant is insufficient (decrease in floc sedimentation speed), the floc itself flocculated will carry over to the treated water side, and Water turbidity may not be improved. Therefore, in step S1, the injection amount of the inorganic coagulant is increased by the chemical injection control shown in FIG. 4, and in step S2, it is determined from the measured value of the turbidimeter 22 whether or not the turbidity of the treated water has been improved. I do. In this case, when the turbidity has been improved, the process proceeds to step S3, and the injection control of the inorganic coagulant is continued.
[0032]
If the turbidity of the treatment water has not been improved by the injection of the inorganic coagulant, the process proceeds to step S4, in which the injection of the polymer coagulant is controlled according to the turbidity, and the process returns to step S2. The injection control of the polymer flocculant is performed by driving the injection pump 8 through the inverter 16 to inject the polymer flocculant from the polymer storage tank 12 into the flocculation reaction tank 2, which is controlled by the sample value PI control of FIG. And the correction control is executed. In this case, by controlling the injection rate of the polymer flocculant in multiple stages according to the output value of the turbidity of the treated water, it is possible to expand the range of response to fluctuations in the flow rate of wastewater and water quality. Become.
[0033]
When such a polymer coagulant injection control is used in combination, the PAC feedback control based on the turbidity of the treated water does not improve the turbidity of the treated water, that is, when the turbidity exceeds a certain value. Recognizing that there is a shortage of the polymer flocculant (decrease in floc sedimentation speed), the injection amount of the polymer flocculant is increased, and as a result, excessive addition of an inorganic flocculant such as PAC by automatic control is prevented. be able to.
[0034]
Further, in the medicine injection control device of the present invention, the controller 24 of the embodiment shown in FIG. 1 may be configured, for example, as in the embodiment shown in FIG. In this embodiment, by providing the controller 24 with the limit value setting unit 38, one or both of the upper limit SPH and the lower limit SPL are set for the measurement (PV) value of the turbidity of the treated water. Using the limit value as the calculation information, for example, the medicine injection control shown in FIG. 8 is performed. In this case, the upper limit SPH is set to a value larger than the target (SP) value of the sample value PI control, and the lower limit SPL is set to a value smaller than the target (SP) value of the sample value PI control.
[0035]
As described in the first embodiment, when the turbidity of the treated water exceeds the upper limit SPH during the execution of the sample value PI control, a certain amount (α) is added to the chemical injection output value (= MV). If the turbidity of the treated water is lower than the lower limit SPL, a certain amount (β) is subtracted from the MV value to correct the MV value. In this case, the value to be added to or subtracted from the chemical injection output (MV) value is not a fixed amount, but a variation obtained according to a value corresponding to a change in turbidity, a value exceeding the upper limit SPH, or a value below the lower limit SPL. The values may be f (α) and g (β).
[0036]
9 (A) to 9 (C) are examples of this control, where (A) is a change in turbidity of raw water, (B) is a measured (PV) value, and (C) is a chemical injection output (MV) value. Where TD is the delay time of the system and TS is the sampling time interval. For the measurement (PV) value, an upper limit SPH and a lower limit SPL are set with respect to the target (SP) value. In this case, when the measured value exceeds the upper limit SPH, injection volume MV ₂ of constant value coagulant injection amount MV ₁ obtained by the sample value PI control is added, also below the lower limit SPL measurements when the injection amount MV ₂ of constant value is subtracted coagulant injection amount MV _1. This is expressed by the following equation.
MV = MV ₁ + MV ₂ ... (4)
MV = MV ₁ −MV ₂ (5)
[0037]
Therefore, with such a coagulant injection amount, when the water quality of the treated water changes suddenly, even within the holding time of the sample value PI control, it is possible to perform the chemical injection control corresponding to the sudden change in the water quality. The water quality can be stabilized.
[0038]
Even when such a control is performed, if the flow rate load is high, even if the amount of the inorganic flocculant is increased, the injection amount of the polymer flocculant becomes insufficient (the sedimentation speed of the floc is reduced), and the floc itself itself is flocculated. Is carried over to the treated water side, and when the turbidity of the treated water is not improved, the injection control of the polymer flocculant shown in the flowchart of FIG. 6 may be used together, and similarly, excessive injection of the inorganic flocculant such as PAC. Can be prevented.
[0039]
In the embodiments shown in FIGS. 5 and 9, the holding time TS of the measured value PV by the sample and hold processing is set to be equal to the delay time TD of the system (TS = TD). Is also good.
[0040]
Further, in the above-described embodiment, the PAC or the high molecular drug is used as an example of the chemical to be injected into the raw water that is the water to be treated. And control of injection of various drugs, and is not limited to injection of a coagulant.
[0041]
Further, in the above embodiment, the controller 24 is described as the chemical injection control device. However, the present invention uses the raw water which is the water to be treated as the input and the treated water as the output, and converts the water treatment system described in the embodiment into the chemical. The invention may be regarded as an injection control device, and the invention disclosed in the embodiment includes the technical ideas listed below.
[0042]
That is, as a chemical injection control device of a water treatment system that performs solid-liquid separation of water to be treated by adding a coagulant, a coagulant (PAC, inorganic coagulant, polymer coagulant) is injected into water to be treated (raw water). A coagulant injecting means (coagulant storage tank 4, infusion pumps 6 and 8), and a turbidity detecting means (turbidity meter 22) for detecting turbidity of treated water after solid-liquid separation by injecting the coagulant. The injection amount of the flocculant is calculated by using the turbidity detected by the turbidity detecting means, and the injection amount is held for a predetermined time (holding time TS), and the injection amount is determined by the turbidity change during the holding time. It may be configured to include a control unit (controller 24) for correction. Similarly, the quality of the treated water can be stabilized.
[0043]
Further, in the chemical injection control device of the water treatment system, a time corresponding to a time delay of the treatment system may be used as the holding time.
[0044]
Further, in the chemical injection control device of the water treatment system, turbidity during the holding time (TS) of the injection amount is detected, a deviation between the turbidity and a target value is calculated, and the injection is performed according to the deviation. The amount may be modified.
[0045]
Further, in the chemical injection control device of this water treatment system, when the turbidity during the holding time of the injection amount exceeds a predetermined upper limit (SPH) or falls below a lower limit (SPL), Alternatively, a constant value or a value corresponding to a change in turbidity may be added or subtracted.
[0046]
In the chemical injection control device for the water treatment system, the upper limit of the turbidity may be a value exceeding the target value, and the lower limit of the turbidity may be a value lower than the target value.
[0047]
Further, in the chemical injection control device of the water treatment system, when the detected turbidity of the turbidity detecting means does not change even if the injection amount of the inorganic coagulant into the water to be treated is increased, the coagulant injection is performed. The polymer coagulant may be injected into the water to be treated by a means.
[0048]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
a It is possible to perform chemical injection control capable of promptly responding to a rapid change in water quality on the treated water side, and to stabilize the quality of treated water.
b Even when used in a drainage system or the like in which feed-forward control is difficult, it is hardly affected by time delay in the coagulation reaction tank, and stabilizes the turbidity of treated water and responds to sudden fluctuations in water quality. Stabilization can be achieved.
c Only the feedback control based on the turbidity value of the treated water can eliminate the delay of the initial response and stabilize the quality of the treated water.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a drug injection control device of the present invention.
FIG. 2 is a block diagram illustrating functions and configurations of a controller.
FIG. 3 is a block diagram illustrating a configuration of a controller.
FIG. 4 is a flowchart showing a medicine injection control in the medicine injection control device according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a chemical injection control timing according to the first embodiment of the present invention.
FIG. 6 is a flowchart showing a drug injection control using a polymer coagulant in combination.
FIG. 7 is a block diagram illustrating a configuration of a controller according to a second embodiment of the drug injection control device of the present invention.
FIG. 8 is a flowchart showing a drug injection control in a drug injection control device according to a second embodiment of the present invention.
FIG. 9 is a diagram showing a chemical injection control timing according to the second embodiment of the present invention.
[Explanation of symbols]
4 flocculant storage tank (drug injection means)
6, 8 injection pump (drug injection means)
22 Turbidimeter (liquid quality measurement means)
24 Controller (control means)
25 injection amount calculating means 27 calculation result holding means 29 correction amount calculating means 31 output means

Claims

A drug injection control device that controls the injection amount of a drug in a water treatment system that includes a drug injection unit that injects a drug into water to be treated, and that performs drug injection,
Liquid quality measuring means for measuring the liquid quality of the treated water after the chemical injection,
Based on the measurement result of the liquid quality measuring means, calculating means for calculating the injection amount of the chemical to the water to be treated,
Calculation result holding means for holding a calculation result obtained by the calculation means for a predetermined time;
Based on the measurement result of the liquid quality measurement unit, a correction amount calculation unit that calculates a correction amount of the injection amount,
An output unit that corrects the injection amount held by the calculation result holding unit with a correction amount obtained by the correction amount calculation unit, and outputs an injection amount of the medicine using the result,
A drug injection control device comprising:

A chemical injection control device for controlling the injection amount of a flocculant in a water treatment system that includes a flocculant injecting unit that injects a flocculant into the water to be treated and that performs a solid-liquid separation of the water to be treated after the flocculant injection,
Liquid quality measuring means for measuring the liquid quality of the treated water after the solid-liquid separation,
Based on the measurement result of the liquid quality measuring means, calculating means for calculating the injection amount in the coagulant injection means,
Calculation result holding means for holding a calculation result obtained by the calculation means for a predetermined time;
Based on the measurement result of the liquid quality measurement unit, a correction amount calculation unit that calculates a correction amount of the injection amount,
Output means for correcting the injection amount held by the calculation result holding means with a correction amount obtained by the correction amount calculation means, and outputting the injection amount of the flocculant using the result,
A drug injection control device comprising:

3. The drug injection control device according to claim 1, wherein the correction amount calculating means sets a difference between a preset liquid quality target value and a measurement result obtained from the liquid quality measuring means as a correction amount.

The correction amount calculating means compares an upper limit value and / or a lower limit value of a preset liquid quality measurement result with a measurement result obtained from the liquid quality measurement means, and when the measured value exceeds the upper limit value, or 3. The drug injection control device according to claim 1, wherein when the value is lower than the predetermined value, a predetermined increase in the amount of the medicine injection or a predetermined amount of the decrease in the medicine injection is set as the correction amount.

The correction amount calculation means compares the measurement result obtained from the liquid quality measurement means with an upper limit value and / or a lower limit value of a preset liquid quality measurement result, and when the measurement value exceeds the upper limit value, or When the value falls below the lower limit value, the predetermined amount is increased or decreased, and at least one of the increased amount and decreased amount is obtained from a preset target value of the liquid quality and the liquid quality measuring means. 3. The drug injection control device according to claim 1, wherein a result calculated using the difference between the measured results is used as a correction amount.