JP3919161B2 - Method and apparatus for heat sterilization of liquid to be treated - Google Patents

Description

【００２０】
図２は本発明の滅菌方法の流れ図の一例を示す。以下、図１のブロック図と図２の流れ図とを参照して本発明の滅菌方法を説明する。先ずステップ201において、加熱器２に滅菌温度が得られる熱量を加えつつ、被処理液Ａの加熱器２への流入を開始する。被処理液Ａの流入開始時は加熱器２の加熱不足が発生しがちであるが、本発明者は、被処理液Ａの流入を加熱器２の一通過工程（ワンパス）で滅菌温度に昇温できる初期流量で開始することにより、滅菌不十分な被処理液Ａの発生を避け得ることに注目した。流入開始時に被処理液Ａを滅菌温度に昇温できれば、その後は保持手段３から戻る処理済液Ｅにより予熱器６、７が働くので、加熱器２の出口は徐々に滅菌温度以上に上昇する。この温度上昇に応じて被処理液Ａの流量を制御することにより、滅菌不十分な被処理液Ａの発生を避けながら被処理液Ａの流量を滅菌路４の定常流量（例えば、滅菌路４において135℃に90秒以上保持できる最大流量）まで増やすことができる。この場合、加熱器２の容量の増加により流入初期段階の加熱不足を避けることも可能であるが、省スペース及び省エネルギーの点からは被処理液Ａの流量制御による方が望ましい。
【００２１】
図２のステップ201では、加熱器２への流入開始時に被処理液Ａを加熱器２の出口で滅菌温度となる初期流量で流入させ、加熱器２の出口の液温が滅菌温度となるように流量を制御する。このような流量処理は、図１の送入路11に設けた流量制御手段20により実現できる。流量制御手段20の一例は、与えられた目標値に従って送入路11の流量を制御すると共に、温度検出器８の出力信号によって流量の目標値を変えるように構成したカスケード制御計である。例えば、温度検出器８の出力信号が１〜２℃上昇するに応じて流量の目標値を変更する。図１の符号５は流量制御手段20により制御可能なポンプ等の送入手段を示す。
【００２２】
加熱器２への被処理液Ａの流入を開始したのち、ステップ202において加熱器２の出口温度を温度検出器８で継続的に検出し、ステップ203において出口温度が不足しているか否かを判断する。ステップ202以降は、定常流量まで増加した後だけでなく、定常流量まで増加する間も継続的に行うことができる。例えば加熱器出口の液温が滅菌温度以上である場合は温度不足なしと判断してステップ207へ進み、出口温度が滅菌温度に保たれるように被処理液Ａの流量及び／又は加熱器２に加える熱量を制御する。加熱器２を熱交換器とした図１の例では、ステップ207において熱媒入力弁V7の開度の調節により加熱器２の出口温度を制御する。ただし、ステップ207における制御は図示例に限定されず、従来技術に属する他の制御技術を用いることができる。
【００２３】
ステップ203において温度不足と判断した場合はステップ204へ進み、抜取手段10により送入路11の開閉弁V3を閉鎖し、滅菌不十分な被処理液Ａが滅菌路４の下流路へ流出するのを防止する。保持手段３による保持時間では６桁滅菌が確保できないような加熱器２の出口の液温低下又はその持続、例えば（滅菌温度−２℃）の液温の１分間以上の持続は温度不足に該当する。また、加熱器２により被処理液Ａを滅菌温度より２℃程度高温に加熱し、加熱器出口で（滅菌温度−２℃）程度の液温が検出された時点で温度不足と判断してもよい。更にステップ205において温度不足の原因を調査し、例えば熱媒入力弁V7、流量制御手段20、送入手段５等の装置・器具に異常が無いことを確認する。必要な場合は装置・器具を修理又は調整する。
【００２４】
装置・器具に異常が無いことを確認したのち、ステップ206において抜取手段10により切替手段V1・V2を抜取路14側へ切り替え、加熱器２及び保持手段３内の滅菌不十分な残留液を排液溜18へ抜き取る。例えば排液溜18を加熱前の被処理液Ａの貯液槽19（図１参照）とし、抜き取った残留液を他の被処理液Ａと共に再び滅菌路４へ戻すことができる。また、後述するライン洗浄ユニット16を排液溜18とし、排液溜18に抜き取った残留液をライン洗浄ユニット16においてバッチ処理により加熱滅菌又は化学滅菌することも可能である。ライン洗浄ユニット16を排液溜18とする場合は、抜取路14上に設けた切替手段V5、V6を抜取手段10により洗浄ユニット16側へ切り替える。切替手段V5、V6の一例も、切替手段V1、V2と同様の一対の開閉弁又は切替弁である。
【００２５】
加熱器２及び保持手段３内の残留液は、例えば抜取路14上に設けた引抜ポンプ（図示せず）等により排液溜18へ引き抜くことができる。また、送入路11に洗浄液V4を介して連通する洗浄液槽17（図１参照）を設け、洗浄液弁V4の開放により送入路11から加熱器２へ流入させた洗浄液Ｉにより前記残留液を排液溜18に押し出してもよい。この場合は、洗浄液Ｉを水酸化ナトリウム（NaOH）、水酸化カルシウム（Ca(OH)₂）等の添加により蛋白質が沈澱しないpHとした水溶液とし、残留液の押し出し時に加熱器２及び保持手段３内における蛋白質の沈澱を抑制することが望ましい。また、ステップ201における被処理液Ａの流量制御と同様に、洗浄液Ｉの流入を加熱器２の出口で滅菌温度となる初期流量で開始し、加熱器２の出口の液温が滅菌温度となるように洗浄液Ｉの流量を制御することにより、洗浄液Ｉを滅菌しながら前記残留液を押し出すことも可能である。このような洗浄液Ｉの流量制御も、図１の流量制御手段20により実現可能である。前記残留液の抜き取り後に洗浄液弁V4を閉鎖する。
【００２６】
加熱器２及び保持手段３内の残留液を抜き取った後ステップ201へ戻り、被処理液Ａの流入を再開する。流入の再開時も、被処理液Ａを前記初期流量で流入させ、加熱器２の出口の温度上昇に応じて流量を制御することにより、滅菌不十分な被処理液Ａの発生を避ける。すなわち図２の流れ図によれば、滅菌不十分な被処理液Ａの発生を極力抑えることができ、たとえ発生した場合でも滅菌路４の下流路への流出を防止できるので、下流路の微生物及び／又はウィルスによる汚染を確実に防止できる。
【００２７】
こうして本発明の目的である「被処理液を連続的に加熱滅菌する滅菌装置の下流路の汚染を確実に防止できる加熱滅菌方法及び装置」の提供が達成できる。
【００２８】
なお、例えば加熱器２により被処理液Ａを滅菌温度より２℃程度高温に加熱し、加熱器出口で（滅菌温度−２℃）程度の液温を検出した時点で温度不足と判断する場合は、温度不足検出時点で既に加熱器２及び保持手段３内の残留液は滅菌温度に達しているので、ステップ204〜205において残留液の温度が低下しなければステップ206における残留液の抜き取りを省略し、ステップ205からステップ201へ戻してもよい。さらに例えば、送入路11の閉鎖時にも加熱器２による加熱を継続すれば前記残留液の温度低下を防ぐことができ、再開時にステップ201の初期流量及び流量制御を行えば滅菌不十分な被処理液Ａの発生を防止できる。
【００２９】
【実施例】
90m³／日の被処理液Ａを10時間で滅菌処理すると仮定して図１に示す装置を試設計し、図２の流れ図による滅菌処理が可能であることを確認した。先ず、被処理液Ａの温度が30℃であることに基づき、加熱器２の伝熱板で焦げ付きが生じない最小流速0.06ｍ／secが確保できるように、流量制御手段20により被処理液Ａの初期流量を20リットル／分に調整して加熱器２への流入を開始した。この流量の被処理液Ａが加熱器２へ流入してから排出するまでの時間（加熱器２の通過時間）は7.5分間であり、加熱器２の出口で135℃の滅菌温度となることが確認できた。また、被処理液Ａの温度が20℃である場合も、初期流量の調整により加熱器２の出口で135℃の滅菌温度とすることができた。
【００３０】
初期流量での流入を7.5分間以上継続したのち、温度検出器８の出力信号により流量制御手段20の目標値を変更するカスケード制御に移行した。本設計の保持手段３において90秒の保持時間が確保できる最大流量は150リットル／分であり、前記カスケード制御により加熱器２の出口で135℃の滅菌温度を保ちながら被処理液Ａの流量を150リットル／分まで徐々に増加させることができた（ステップ201）。
【００３１】
また、加熱器２の出口の温度不足が発生したと仮定して、抜取手段10により送入路11の開閉弁V3を閉鎖すると共に切替手段V1・V2を抜取路14側へ切り替え、加熱器２及び保持手段３内の滅菌不十分な残留液を排液溜18へ抜き取った（ステップ202〜206）。残留液の抜き取り後、30℃の被処理液Ａの流入を20リットル／分の初期流量で再開し、前記カスケード制御により被処理液Ａの流量を150リットル／分まで増加させた。
【００３２】
この再開過程においても加熱器２の出口で135℃の滅菌温度が保たれることが確認できた。また、再開後に排液路13から排出された処理済液Ｅ中の生菌数を確認したところ、６桁滅菌が確保できていることが確認できた。このことから、前記流量のカスケード制御と残留液の抜き取りとにより、滅菌路４の下流路の微生物及び／又はウィルスによる汚染が防止できることが確認できた。
【００３３】
比較のため、前記カスケード機能のない流量制御手段20を設けた図１の装置に、90m³／日の被処理液Ａ（温度30℃）を150リットル／分の流量で流入させたところ、被処理液Ａの流入初期段階において加熱器２の出口の温度検出器８は90℃程度までしか上昇しなかった。被処理液Ａの流入の継続により加熱器２の出口温度は135℃の滅菌温度に上昇したが、滅菌温度まで上昇後に処理済液Ｅ中の生菌数を確認したところ６桁滅菌が確保できていないことが確認された。これは、流入初期段階の滅菌不十分な被処理液Ａが滅菌路４の下流路へ流れ出たことにより下流路が微生物やウィルスにより汚染され、滅菌温度まで上昇した後も下流路で再汚染が起こるからと考えられる。この比較実験から、本発明における被処理液Ａの流量のカスケード制御と残留液の抜き取りとが６桁滅菌の確保に極めて有効であることが確認できた。
【００３４】
図１の実施例では、加熱器２を熱媒（蒸気）と被処理液Ａとの熱交換器とし、２段の予熱器６、７を被処理液Ａと同量の処理済液Ｅとが流入する熱交換器としている。例えば被処理液Ａの受け入れ温度を30℃とし、90m³／日の被処理液Ａを加熱器２で135℃に昇温して90秒保持するとした場合、予熱器６、７の伝熱面積を45m²、加熱器２の伝熱面積を８m²とすると、被処理液Ａは前段予熱器６により75℃に昇温し、後段予熱器７により120℃に昇温し、加熱器２により135℃となる。また、保持手段３から排出される処理済液Ｅは後段予熱器７により90℃まで降温し、前段予熱器６により45℃となる。この場合、加熱器２には４KGの蒸気圧力で300kg／時の熱媒（蒸気）を投入すれば足りる。
【００３５】
他方、90m³／日の被処理液Ａをキルタンク（直接蒸気投入式の密閉容器）又は単一の直接熱交換器を用いて135℃、90秒保持の滅菌処理をする場合は、必要な蒸気量は2,200kg／時となる。更にこの場合は、保持手段３通過後の処理済液Ｅを降温するため、別途に降温エネルギーを加えるか又は降温する時間とスペースが必要となる。このことから、本発明のように予熱器６、７を設けることにより、外部から供給するエネルギーの節減により省エネルギーが図れることを確認できた。
【００３６】
本発明は予熱器を１台の熱交換器とした場合も適用できるが、熱交換器１台で30℃の被処理液Ａを120℃まで昇温しようとすると熱交伝面を大きくする必要があり、熱交伝面が大きくなると偏流が発生しやすくなり、偏流は被処理液Ａの温度分布ムラの原因となる。加熱殺菌における被処理液Ａの温度分布ムラの発生は、滅菌温度に加熱できない部分が生じるおそれがあるので好ましくない。
【００３７】
本発明者は、低温流体と同量の高温流体とが流入する熱交換器において、低温流体の入口温度と高温流体の出口温度との温度差ΔT1に対する低温流体の上昇温度又は高温流体の下降温度ΔT2（交換温度差）の比（ΔT2／ΔT1）が４より大きくなると、前記温度分布ムラが発生しやすいことを実験的に見出した。例えば、図１の予熱器を１台の熱交換器とすると、交換温度差ΔT2（低温流体である被処理液Ａの上昇温度又は高温流体である処理済液Ｅの下降温度）は90℃（＝120℃−30℃）であり、低温流体である被処理液Ａの入口温度と高温流体である処理済液Ｅの出口温度との温度差ΔT1は15℃（45℃−30℃）であるから、前記比ΔT2／ΔT1は６（＝90／15）となり温度分布ムラの発生が懸念される。
【００３８】
図１の実施例では、低温流体と同量の高温流体とが流入する熱交換器を直列に接続した多段熱交換器を予熱器６、７とし、各熱交換器における前記比ΔT2／ΔT1を４以下、好ましくは３程度とすることにより、被処理液Ａの温度分布ムラの発生を予防している。すなわち、図１の前段予熱器６では交換温度差ΔT2は45℃（＝75℃−30℃）、低温流体の入口温度と高温流体の出口温度との温度差ΔT1は15℃（45℃−30℃）であるから前記比ΔT2／ΔT1は３（＝45／15）となる。また、後段予熱器７においても交換温度差ΔT2は45℃（＝120℃−75℃）、低温流体の入口温度と高温流体の出口温度との温度差ΔT1は15℃（90℃−75℃）であるから前記比ΔT2／ΔT1は３（＝45／15）となる。被処理液Ａの温度分布ムラの発生を予防することにより、滅菌温度に加熱できない部分の発生の防止が期待できる。
【００３９】
図１における加熱器２、及び予熱器６、７として使う熱交換器に特に制限はないが、例えばスパイラル式熱交換器とすることができる。スパイラル式熱交換器は多管式熱交換器に比し流路が単一で滑らかである。このため、熱交換器の配管内にスケールが付着すると付着箇所の断面積が小さくなることによって流速が増大し、スケールを剥離させる自己浄化作用が働く。従ってスパイラル式熱交換器の使用により、スケールが付着し難くメンテナンスが容易な装置とすることが期待できる。
【００４０】
更に図１の実施例では、加熱器２へ送る被処理液Ａの貯液槽19にpH調整装置32を設け、被処理液Ａを微生物及び／又はウィルスの構成蛋白質やその他の有機物が滅菌による変性後も沈澱しないpHとすることにより、輸液路内への蛋白質の沈澱を抑制している。また、輸液路内に蛋白質又は無機物等のスケールが沈澱・付着した場合の対策として、予熱器６、７通過後の処理済液Ｅの排液路13と送入路11との間に弁V8、V9、V10を介してライン洗浄ユニット16を接続している。送入路11と滅菌路４と放出路12と予熱装置６、７とからなる輸液路の洗浄時に、弁V8、V9、V10の切替により、前記輸液路とライン洗浄ユニット16とからなる閉流路を形成する。
【００４１】
例えば滅菌処理の開始前又は中断時に、開閉弁V3を閉鎖して弁V10を開放することによりライン洗浄ユニット16を送入路11に接続し、切替手段V8、V9を洗浄路15側へ切り替え、前記閉流路にスケール除去剤その他の薬液を循環させることにより前記輸液路内を洗浄する。切替手段V8、V9の一例も一対の開閉弁又は切替弁である。好ましくは前記輸液路をステンレス製とし、硝酸を循環させる。硝酸はスケールを溶解すると共にステンレス配管に不動態皮膜を形成し耐食性を増加させる。不動態皮膜の形成により寿命の長い装置とすることが期待できる。ただし、薬液は硝酸に限定されず他の適当な酸又はアルカリ等を利用することができる。
【００４２】
ライン洗浄ユニット16は、前記輸液路のあらゆる部分に十分な量の適切な温度の洗浄液又は蒸気を行き渡らせる従来技術のCIPユニットとすることができる。加熱器２を熱交換器とした場合は、加熱器２の出口蒸気をライン洗浄ユニット16へ導いて再利用することにより、全ての輸液路及び装置を熱洗浄ないし熱滅菌（Sterilization-in-place、SIP）することが可能である。薬液のみでなく蒸気を用いた簡易滅菌により、装置の開放点検などの頻度を減らし、メンテナンスの更なる容易化を図ることができる。
【００４３】
【発明の効果】
以上詳細に説明した通り、本発明による被処理液の加熱滅菌方法及び装置は、被処理液を加熱器で滅菌温度に加熱のうえ保持手段で所要時間保持し且つ保持後の処理済液を予熱器に導いて加熱前の被処理液の予熱に用いる加熱滅菌において、保持手段と予熱器との間に抜取路を切替手段経由で接続し、加熱器出口の温度不足検出時に加熱器への被処理液の流入を停止すると共に前記切替手段を抜取路側へ切り替えて加熱器及び保持手段内の残留液を抜き取るので、次の顕著な効果を奏する。
【００４４】
（イ）滅菌不十分な被処理液が滅菌装置の下流路へ流出するのを防止できるので、下流路の微生物及び／又はウィルスによる汚染を確実に防止できる。
（ロ）抜き取った残留液を加熱前の被処理液の貯液槽等に戻し、容易に再滅菌処理することが可能である。
（ハ）被処理液を加熱器出口で滅菌温度となる初期流量で流入させ、加熱器出口の温度上昇に応じて流量を増加させる被処理液の流量制御と組合わせることにより、滅菌不十分な被処理液の発生を極力防止しながら被処理液を連続的に処理することができる。
（ニ）大量の被処理液を連続的に処理することが可能であり、省スペースかつコンパクトな装置とすることができる。
【００４５】
（ホ）被処理液を蛋白質が沈澱しないpHとすることにより、配管の閉塞等を避けつつ、大量の被処理液を連続的に処理することが可能である。
（ヘ）加熱器経由で流入させた洗浄液で残留液を抜き取る場合は、洗浄液を蛋白質が沈澱しないpHとすることにより、抜き取り時の蛋白質の沈澱等を避けることができる。
（ト）高温の処理済液を加熱前の被処理液の予熱に用いるので、直接蒸気投入等のバッチ式熱処理法に比し、外部から供給するエネルギーを減らして省エネルギーが図れる。
【００４６】
（チ）加熱処理により滅菌するので、薬液では充分に滅菌できない細菌・ウィルスも、滅菌温度及び時間の調整により確実に不活化することが可能である。
（リ）薬剤による滅菌処理に比し環境を汚染するおそれが少ない。また、薬剤コストが削減できるのでランニングコストを大幅に削減できる。
（ヌ）例えば蒸気圧力を変えることで任意に滅菌温度（不活化温度）を変更することが可能であり、将来の未知の細菌やウィルスを含む排水の滅菌処理にも容易に対応可能である。
【図面の簡単な説明】
【図１】は、本発明装置の一実施例のブロック図である。
【図２】は、本発明方法を示す流れ図の一例である。
【図３】は、従来の滅菌装置の説明図である。
【符号の説明】
１…滅菌装置 ２…加熱器
３…保持手段 ４…滅菌路
５…送入手段 ６…前段予熱器
７…後段予熱器 ８…温度検出器
９…圧力検出器 10…抜取手段
11…送入路 12…放出路
13…排液路 14…抜取路
15…洗浄路 16…ライン洗浄ユニット
17…洗浄液槽 18…排液溜
19…貯液槽 20…流量制御手段
31…原水受槽 32…pH調整装置
33…熱交換装置 34…熱交換器
35…ホールディングチューブ
36…温度センサ 37…圧力センサ
38…送水管 39…輸液ポンプ
40…温度センサ 41…放水管
42…予熱装置 43…予熱装置
44…管路洗浄ユニット 45…弁
46…弁
Ａ…被処理液 Ｅ…処理済液
Ｇ…熱媒 Ｉ…洗浄液
A'…微生物及び／又はウィルス含有排水
B'…昇温排水 C'…昇温排水
D'…高温排水 E'…滅菌済排水
F'…低温排水 G'…蒸気
H'…処理水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for heat sterilization of a liquid to be treated, and particularly refers to one or more microorganisms and / or viruses (bacteria, filamentous fungi, yeast, cyanobacterium, protozoa, virus / phage, prion, etc.). The same shall apply hereinafter.) The present invention relates to a heat sterilization method and apparatus for inactivating waste liquid, waste water and other liquids to be treated.
[0002]
[Prior art]
In facilities such as pharmaceutical factories and hospitals for blood products that discharge waste liquids and wastewater (hereinafter sometimes referred to as liquids to be treated) that are concerned about the presence of microorganisms and / or viruses, In addition to preventing infection, inactivation of the liquid to be treated discharged outside the facility is required. The inactivation of the liquid to be treated is to suppress the activities of microorganisms and viruses in the liquid to be treated, and the conditions vary depending on the types of microorganisms and viruses, but sterilization, sterilization, disinfection, etc. Is achieved.)
[0003]
Conventionally, the liquid to be treated is (1) separated and incinerated by pH adjustment and coagulation precipitation, and the liquid phase is sterilized with a chemical such as sodium hypochlorite and then neutralized with excess chemicals. Sterilization such as a method of discharging outside the facility, (2) a method of storing in a kill tank, autoclave, etc., direct injection of steam or chemicals by batch processing, heat treatment or chemical treatment, and discharging outside the facility . However, since sterilization with chemicals requires a large amount of chemicals and incineration energy, there is a problem that running costs increase. In addition, since sterilization using a kill tank or autoclave is a batch type, a large-scale device is required, and there is a problem that equipment costs increase.
[0004]
On the other hand, if a heat exchanger is used, the liquid to be treated can be continuously processed with a relatively small apparatus, so that economical sterilization can be expected. However, in sterilization using a heat exchanger, microorganisms, viruses, and other organic substances (for example, plasma proteins in the liquid to be treated such as blood products) that are solidified and denatured during heat treatment are transmitted (electrical) in the heat plate or piping. There is a risk that the pipe will be blocked by sedimentation.
[0005]
The present inventor has developed a sterilization method and apparatus using a heat exchanger that does not cause clogging of piping by passing the liquid to be treated through a heat exchanger at a pH at which protein does not precipitate, and disclosed in Japanese Patent Application No. 2000-165344. . Referring to FIG. 3, the sterilization apparatus of the same application includes a raw water receiving tank 31 for storing microorganisms and / or virus-containing waste water A ′, a pH adjusting device 32 for adjusting the pH of the waste water A ′ in the raw water receiving tank 31, and a waste water A ′. A heat exchange device 33 for holding the sterilization temperature for a required time, and a water supply pipe 38 for sending the waste water A ′ in the raw water receiving tank 31 to the heat exchange device 33, and the waste water A ′ is microorganisms and / or viruses by the pH adjustment device 32. After the pH is adjusted such that the constituent protein of the protein does not precipitate even after denaturation by sterilization, the protein is sent to the heat exchanger 33. The heat exchanging device 33 raises the waste water A ′ to the sterilization temperature by the heat exchanger 34 and holds the high temperature waste water D ′ at the sterilization temperature by the holding tube 35 for a required time. The sterilization effect by the heat exchange device 33 is not affected by the pH of the drainage A ′. According to the sterilization apparatus shown in the figure, protein precipitation can be suppressed, so that maintenance and management can be facilitated and running costs can be reduced.
[0006]
Furthermore, by providing preheating devices 42 and 43 for raising the temperature by exchanging heat with the sterilized waste water E ′ after maintaining the waste water A ′ before passing to the heat exchange device 33 at the sterilization temperature in the water pipe 38, the heat exchange device The energy required for the temperature increase at 33 and the temperature decrease of the sterilized waste water E ′ can be reduced and the energy required for the temperature increase can be recovered and reused, thereby further reducing the running cost. Reference numeral 36 in the figure denotes a temperature sensor that measures the liquid temperature at the outlet of the heat exchanger 34, and reference numeral 37 denotes a pressure sensor that measures the pressure in the holding tube 35.
[0007]
[Problems to be solved by the invention]
However, in the sterilizer that continuously treats the wastewater A ′ as shown in FIG. 3, the wastewater A ′ is insufficiently heated at the initial stage of the inflow of the wastewater A ′ or at any abnormality (when the flow control is malfunctioning or the pump is broken). There is a problem to get. Generally, Sterility Assurance Level is the initial viable count N ₀ Survival rate of viable bacterial count N after sterilization (= N / N ₀ ) Is one millionth (10 ^-6 ) It is defined as follows (Masayoshi Furuhashi, “Sterilization and Disinfection Manual”, Nihon Hoshin Shinposha, January 1999, p37, hereinafter referred to as 6-digit sterilization). For example, 6-digit sterilization of general bacteria requires holding at 121 ° C. for 9 minutes (preferably 15 minutes) or more, and at 134 ° C. for 0.45 minutes (preferably 3 minutes) or more. In addition, 6-digit sterilization of hepatitis B virus requires holding at 98 ° C for 2 minutes, and at 108 ° C for 72 seconds (see "Sterilization and disinfection manual" above, p49. Sterilization method and microbial killing method "Japanese Standards Association, February 1998, p19). Thus, securing 6-digit sterilization requires heating to the sterilization temperature and maintaining the sterilization temperature for the required time. Therefore, if the sterilization temperature cannot be obtained due to insufficient heating of the heat exchanger 34, the holding tube 35 is used. With this holding time, 6-digit sterilization cannot be secured, and the drainage A ′ may flow out to the preheating devices 42 and 43 and the downstream discharge pipe 41 with insufficient sterilization.
[0008]
If the drainage A ′ flows out of the holding tube 35 with insufficient sterilization, simply collecting the drainage A ′ does not solve the problem, and the pipe line downstream of the holding tube 35 (hereinafter referred to as the lower flow path of the sterilizer). There is a problem of contamination by microorganisms and viruses. When the lower flow path is contaminated with microorganisms or viruses, the sterilized drainage E ′ from the holding tube 35 passes through the lower flow path even if the heating of the heat exchange device 33 recovers and 6-digit sterilization can be secured. The process can be recontaminated by microorganisms and / or viruses. In particular, in the example of FIG. 3 in which the preheating devices 42 and 43 are provided, the temperature of the sterilized waste water E ′ is lowered in the preheating devices 42 and 43, so that the sterilization action of the lower flow path by the sterilized waste water E ′ cannot be expected. Therefore, when the lower flow path of the sterilizer is contaminated, a large-scale disinfection operation or construction such as decomposition and sterilization of the lower flow path is required. In the continuous heat sterilization treatment of the liquid to be treated, it is necessary to take measures to prevent contamination by microorganisms and / or viruses in the lower flow path of the sterilizer and avoid recontamination in the lower flow path.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a heat sterilization method and apparatus that can reliably prevent contamination of a downstream path of a sterilization apparatus that continuously sterilizes a liquid to be treated.
[0010]
[Means for Solving the Problems]
Referring to the block diagram of FIG. 1 and the flowchart of FIG. 2, the method for heat sterilization of the liquid to be treated according to the present invention is to heat the liquid A to be sterilized by the heater 2 and hold it for the required time by the holding means 3. In the heat sterilization method used for preheating the treated liquid A before heating by introducing the treated liquid E after holding to the preheaters 6 and 7, a drainage reservoir 18 is provided between the holding means 3 and the preheaters 6 and 7. Is connected via switching means V1 and V2 to stop the inflow of liquid A into the heater 2 and detect the switching means V1 and V2 when the temperature is detected at the outlet of the heater 2 Switch to the 14 side, drain the residual liquid in the heater 2 and the holding means 3 to the drainage reservoir 18, return the switching means V1 and V2 when sterilization resumes, and resume the inflow of the liquid A to be treated into the heater 2 It will be.
[0011]
Preferably, the residual liquid is pushed out to the drainage reservoir 18 by the cleaning liquid I introduced via the heater 2 when the temperature shortage at the outlet of the heater 2 is detected. More preferably, at the start or resumption of the inflow of the liquid A or the cleaning liquid I into the heater 2, the inflow liquid is caused to flow at an initial flow rate at a sterilization temperature at the outlet of the heater 2, and the liquid at the outlet of the heater 2 is discharged. The flow rate of the liquid A or the cleaning liquid I is controlled so that the temperature becomes the sterilization temperature.
[0012]
Referring to the block diagram of FIG. 1, the apparatus for heat sterilization of a liquid to be processed according to the present invention includes a heater 2 for heating the liquid A to be sterilized and a liquid A to be processed communicating with the inlet of the heater 2. The opening / closing valve V3 provided in the inlet 11 and the outlet of the heater 2 hold the liquid A to be processed at the sterilization temperature for a required time. The processed liquid E after passing through the holding means 3 is heated before being heated. Preheaters 6 and 7 for raising the temperature of the processing liquid A, drainage reservoir 18, extraction means 14 connected to holding means 3 and preheaters 6 and 7 via switching means V 1 and V 2, heater 2 Temperature detector 8 for detecting the liquid temperature at the outlet of the gas generator, and when temperature shortage is detected by the temperature detector 8, the on-off valve V3 is closed and the switching means V1 and V2 are switched to the extraction path 14 side to heat the heater 2 and the holding means 3 It is provided with extraction means 10 for extracting the residual liquid in the waste liquid reservoir 18.
[0013]
Preferably, a cleaning liquid tank 17 communicating with the inlet 11 via the cleaning liquid valve V4 is provided, and when the temperature shortage is detected, the cleaning liquid valve V4 is opened and the residual liquid is drained by the cleaning liquid I introduced via the heater 2. Extrude to reservoir 18 More preferably, when the inflow of the liquid to be treated A or the cleaning liquid I into the heater 2 is started or resumed, the inflow liquid flows into the inlet path 11 at an initial flow rate at a sterilization temperature at the outlet of the heater 2 and is heated. A flow rate control means 20 is provided for controlling the flow rate of the liquid A or the cleaning liquid I so that the liquid temperature at the outlet of the vessel 2 becomes the sterilization temperature.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 shows CIP (Cleaning in Place) in a pharmaceutical facility / factory, hospital, etc. for blood products, etc., and automatic cleaning that is performed without any additional equipment or disassembling the production equipment. The same applies hereinafter.) A block diagram of an embodiment in which the present invention is applied to the sterilization of the liquid A to be treated, such as waste water, washing waste water from a washing room, floor waste water and the like. Referring to the figure, the heat sterilization apparatus of the present invention is connected to the heater 2 for heating the liquid A to be sterilized to the sterilization temperature, and holds the liquid A to be processed at the sterilization temperature for the required time. Holding means 3 such as a holding tube, and preheaters 6 and 7 for raising the temperature of the liquid A to be processed before being heated by the processed liquid E after passing through the holding means 3.
[0015]
The heater 2 and the holding means 3 constitute a sterilization path 4 that holds the liquid A to be processed at a sterilization temperature corresponding to the type of microorganism / virus for a required time. An example of the heater 2 is a heat exchanger, but the present invention is not limited to heating by a heat exchanger. Preferably, the heating temperature by the heater 2 and the holding time by the holding means 3 can be adjusted, and 6-digit sterilization can be secured in the sterilization path 4 according to the type of microorganism / virus.
[0016]
The present inventor maintains the liquid A to be treated from a pharmaceutical facility of blood products at 135 ° C. for 90 seconds or more in the sterilization path 4 so that the risk of mixing cannot be denied and human immunodeficiency virus (HIV) , Hepatitis viruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV), and all other viruses (WHO: GLOBAL BLOOD SAFETY INITIATIVE) that are currently confirmed to be infected with blood and blood products. In 1992, p374) was experimentally confirmed to be capable of 6-digit sterilization.
[0017]
Furthermore, the heat sterilization apparatus according to the present invention detects the liquid temperature at the outlet 14 of the heater 2 and the extraction path 14 connected between the holding means 3 and the preheaters 6 and 7 via the switching means V1 and V2. When the temperature insufficiency is detected by the heater 8 and the temperature detector 8, the on-off valve V3 of the inlet passage 11 is closed and the switching means V1 and V2 are switched to the extraction path 14 side to remove residual liquid in the heater 2 and the holding means 3 And a draining means 10 for draining into the drainage reservoir 18. An example of the switching means V1 and V2 is a pair of on-off valves or switching valves, which close or open the valve V2 when the valve V1 is opened or closed.
[0018]
At the time of sterilization, the opening / closing valve V3 of the inlet path 11 communicating with the inlet of the heater 2 is opened, and the liquid A to be processed is sent to the sterilization path 4 via the preheaters 6 and 7 by, for example, the flow rate control means 20 described later. . Further, the switching means V1 and V2 between the holding means 3 and the preheaters 6 and 7 are switched to the discharge path 12 side, and the high temperature treated liquid E sterilized in the sterilization path 4 is discharged through the discharge path 12 to the preheater 6 and Returning to 7, the temperature is lowered by heat exchange with the relatively low temperature liquid A to be treated on the inlet path 11, and sent to the drain path 13. The treated liquid E sent to the drainage channel 13 is subjected to neutralization treatment and BOD removal treatment as necessary, and then discharged out of the facility together with general waste liquid / drainage. By utilizing heat exchange between the processed liquid E and the liquid to be processed A, it is possible to minimize the energy required to raise and lower the temperature of the liquid A to be processed.
[0019]
[Table 1]

[0020]
FIG. 2 shows an example of a flow chart of the sterilization method of the present invention. The sterilization method of the present invention will be described below with reference to the block diagram of FIG. 1 and the flowchart of FIG. First, in step 201, the inflow of the liquid A to be treated into the heater 2 is started while adding a heat amount that can obtain a sterilization temperature to the heater 2. Although the heating of the heater 2 tends to be insufficient at the start of the inflow of the liquid A to be treated, the present inventor raised the inflow of the liquid A to the sterilization temperature in a one-pass process (one pass) of the heater 2. It was noted that by starting with an initial flow rate that can be warmed, the generation of the liquid A to be treated which is not sufficiently sterilized can be avoided. If the liquid A to be treated can be heated to the sterilization temperature at the start of the inflow, then the preheaters 6 and 7 are operated by the processed liquid E returned from the holding means 3, so that the outlet of the heater 2 gradually rises above the sterilization temperature. . By controlling the flow rate of the liquid A to be processed according to this temperature rise, the flow rate of the liquid A to be processed is reduced to the steady flow rate of the sterilization path 4 (for example, the sterilization path 4 The maximum flow rate that can be maintained at 135 ° C for 90 seconds or more) can be increased. In this case, although it is possible to avoid heating shortage at the initial stage of the inflow by increasing the capacity of the heater 2, it is more preferable to control the flow rate of the liquid A to be processed from the viewpoint of space saving and energy saving.
[0021]
In step 201 of FIG. 2, the liquid A to be treated is introduced at an initial flow rate at a sterilization temperature at the outlet of the heater 2 at the start of inflow into the heater 2 so that the liquid temperature at the outlet of the heater 2 becomes the sterilization temperature. To control the flow rate. Such flow rate processing can be realized by the flow rate control means 20 provided in the inflow path 11 of FIG. An example of the flow rate control means 20 is a cascade controller configured to control the flow rate of the inlet / outlet path 11 according to a given target value and to change the target value of the flow rate according to the output signal of the temperature detector 8. For example, the flow rate target value is changed as the output signal of the temperature detector 8 increases by 1 to 2 ° C. Reference numeral 5 in FIG. 1 indicates a delivery means such as a pump that can be controlled by the flow rate control means 20.
[0022]
After starting the inflow of the liquid A to be processed into the heater 2, the outlet temperature of the heater 2 is continuously detected by the temperature detector 8 in step 202, and whether or not the outlet temperature is insufficient in step 203. to decide. Step 202 and subsequent steps can be continuously performed not only after increasing to the steady flow rate but also while increasing to the steady flow rate. For example, if the liquid temperature at the outlet of the heater is equal to or higher than the sterilization temperature, it is determined that there is no temperature shortage and the process proceeds to step 207 and the flow rate of the liquid A to be processed and / or the heater 2 is maintained. Controls the amount of heat applied to the. In the example of FIG. 1 in which the heater 2 is a heat exchanger, in step 207, the outlet temperature of the heater 2 is controlled by adjusting the opening of the heat medium input valve V7. However, the control in step 207 is not limited to the illustrated example, and other control techniques belonging to the prior art can be used.
[0023]
If it is determined in step 203 that the temperature is insufficient, the process proceeds to step 204, where the extraction means 10 closes the on-off valve V3 of the delivery path 11, and the liquid A to be treated that is insufficiently sterilized flows out into the lower flow path of the sterilization path 4. To prevent. Lowering or maintaining the liquid temperature at the outlet of the heater 2 where 6-digit sterilization cannot be ensured with the holding time by the holding means 3, for example, maintaining the liquid temperature at (sterilization temperature-2 ° C.) for 1 minute or more corresponds to insufficient temperature. To do. Moreover, even if it judges that the liquid A to be treated is heated to about 2 ° C. higher than the sterilization temperature by the heater 2 and the liquid temperature of about (sterilization temperature −2 ° C.) is detected at the outlet of the heater, the temperature is insufficient. Good. Further, in step 205, the cause of the temperature shortage is investigated and, for example, it is confirmed that there is no abnormality in the devices and instruments such as the heating medium input valve V7, the flow rate control means 20, and the feeding means 5. If necessary, repair or adjust the equipment and instruments.
[0024]
After confirming that there is no abnormality in the device / apparatus, in step 206, the switching means V1 and V2 are switched to the extraction path 14 side by the extraction means 10, and the sterilized insufficient liquid in the heater 2 and the holding means 3 is discharged. Drain into reservoir 18. For example, the waste liquid reservoir 18 can be used as a storage tank 19 (see FIG. 1) of the liquid A to be processed before heating, and the extracted residual liquid can be returned to the sterilization path 4 together with other liquids A to be processed. It is also possible to use a line cleaning unit 16 to be described later as a drainage reservoir 18 and to heat sterilize or chemically sterilize the residual liquid extracted in the drainage reservoir 18 by batch processing in the line cleaning unit 16. When the line cleaning unit 16 is used as the drainage reservoir 18, the switching means V5 and V6 provided on the extraction path 14 are switched to the cleaning unit 16 side by the extraction means 10. An example of the switching means V5, V6 is also a pair of on-off valves or switching valves similar to the switching means V1, V2.
[0025]
The residual liquid in the heater 2 and the holding means 3 can be drawn out to the drainage reservoir 18 by, for example, a drawing pump (not shown) provided on the drawing path 14. In addition, a cleaning liquid tank 17 (see FIG. 1) is provided in the inlet path 11 via the cleaning liquid V4, and the residual liquid is removed by the cleaning liquid I flowing into the heater 2 from the inlet path 11 by opening the cleaning liquid valve V4. It may be pushed out into the drainage reservoir 18. In this case, wash liquid I is sodium hydroxide (NaOH), calcium hydroxide (Ca (OH) ₂ It is desirable that the aqueous solution is adjusted to a pH at which no protein is precipitated by addition of the above and the like, and the protein precipitation in the heater 2 and the holding means 3 is suppressed when the residual liquid is pushed out. Similarly to the flow rate control of the liquid A to be processed in step 201, the inflow of the cleaning liquid I is started at an initial flow rate at which the sterilization temperature is reached at the outlet of the heater 2, and the liquid temperature at the outlet of the heater 2 becomes the sterilization temperature. Thus, by controlling the flow rate of the cleaning liquid I, the residual liquid can be pushed out while sterilizing the cleaning liquid I. Such flow control of the cleaning liquid I can also be realized by the flow control means 20 of FIG. After removing the residual liquid, the cleaning liquid valve V4 is closed.
[0026]
After removing the residual liquid in the heater 2 and the holding means 3, the process returns to step 201, and the inflow of the liquid to be processed A is restarted. Even when the inflow is resumed, the liquid A to be treated is caused to flow at the initial flow rate, and the flow rate is controlled according to the temperature rise at the outlet of the heater 2, thereby avoiding the generation of the liquid A to be treated that is not sufficiently sterilized. That is, according to the flowchart of FIG. 2, the generation of the liquid A to be treated which is not sufficiently sterilized can be suppressed as much as possible, and even if it occurs, the outflow to the lower flow path of the sterilization path 4 can be prevented. It is possible to reliably prevent contamination by viruses.
[0027]
In this way, the object of the present invention can be provided as “a heat sterilization method and apparatus capable of reliably preventing the contamination of the lower flow path of the sterilization apparatus for continuously heat sterilizing the liquid to be treated”.
[0028]
For example, when the liquid A to be treated is heated to about 2 ° C. higher than the sterilization temperature by the heater 2 and a liquid temperature of about (sterilization temperature −2 ° C.) is detected at the outlet of the heater, Since the residual liquid in the heater 2 and the holding means 3 has already reached the sterilization temperature when the temperature shortage is detected, if the temperature of the residual liquid does not decrease in steps 204 to 205, the removal of the residual liquid in step 206 is omitted. However, the process may return from step 205 to step 201. Further, for example, if the heating by the heater 2 is continued even when the inlet path 11 is closed, the temperature of the residual liquid can be prevented from decreasing. Generation of the processing liquid A can be prevented.
[0029]
【Example】
90m ^Three Assuming that the liquid A to be processed / day is sterilized in 10 hours, the apparatus shown in FIG. 1 was trial-designed, and it was confirmed that the sterilization process according to the flowchart of FIG. 2 was possible. First, based on the fact that the temperature of the liquid A to be processed is 30 ° C., the flow rate control means 20 allows the liquid A to be processed to ensure a minimum flow rate of 0.06 m / sec at which the heat transfer plate of the heater 2 does not burn. The initial flow rate of was adjusted to 20 liters / minute, and flow into the heater 2 was started. The time from the flow of the liquid A to be treated flowing into the heater 2 to the discharge thereof (passing time of the heater 2) is 7.5 minutes, and a sterilization temperature of 135 ° C. is reached at the outlet of the heater 2. It could be confirmed. Moreover, even when the temperature of the liquid A to be treated was 20 ° C., the sterilization temperature of 135 ° C. could be achieved at the outlet of the heater 2 by adjusting the initial flow rate.
[0030]
After the inflow at the initial flow rate was continued for 7.5 minutes or more, the flow shifted to cascade control in which the target value of the flow rate control means 20 was changed by the output signal of the temperature detector 8. The maximum flow rate that can secure a holding time of 90 seconds in the holding means 3 of this design is 150 liters / minute, and the flow rate of the liquid A to be treated is maintained at the outlet of the heater 2 while maintaining a sterilization temperature of 135 ° C. by the cascade control. It could be gradually increased to 150 liters / minute (step 201).
[0031]
Assuming that the temperature at the outlet of the heater 2 is insufficient, the extraction means 10 closes the on-off valve V3 of the inlet path 11 and switches the switching means V1 and V2 to the extraction path 14 side. And the residual liquid inadequately sterilized in the holding means 3 was extracted to the drainage reservoir 18 (steps 202 to 206). After extracting the residual liquid, the inflow of the liquid A to be processed at 30 ° C. was restarted at an initial flow rate of 20 liters / minute, and the flow rate of the liquid A to be processed was increased to 150 liters / minute by the cascade control.
[0032]
It was confirmed that a sterilization temperature of 135 ° C. was maintained at the outlet of the heater 2 even during this resumption process. Further, when the number of viable bacteria in the treated liquid E discharged from the drainage channel 13 after resumption was confirmed, it was confirmed that 6-digit sterilization could be secured. From this, it was confirmed that contamination by the microorganisms and / or viruses in the lower flow path of the sterilization path 4 could be prevented by cascade control of the flow rate and extraction of the residual liquid.
[0033]
For comparison, the apparatus shown in FIG. ^Three When the liquid A to be processed (temperature 30 ° C.) was introduced at a flow rate of 150 liters / minute, the temperature detector 8 at the outlet of the heater 2 was only up to about 90 ° C. It did not rise. The outlet temperature of the heater 2 rose to a sterilization temperature of 135 ° C due to the continued inflow of the liquid to be treated A, but when the number of viable bacteria in the treated liquid E was confirmed after the temperature reached the sterilization temperature, 6-digit sterilization could be secured. Not confirmed. This is because the liquid A, which is not sufficiently sterilized at the initial stage of inflow, flows out to the lower flow path of the sterilization path 4, and the lower flow path is contaminated with microorganisms and viruses. It is thought that it happens. From this comparative experiment, it was confirmed that the cascade control of the flow rate of the liquid A to be treated and the extraction of the residual liquid in the present invention are extremely effective for ensuring 6-digit sterilization.
[0034]
In the embodiment of FIG. 1, the heater 2 is a heat exchanger between the heat medium (steam) and the liquid A to be processed, and the two stages of preheaters 6 and 7 are processed liquid E having the same amount as the liquid A to be processed. It is a heat exchanger that flows in. For example, the receiving temperature of the liquid A to be treated is 30 ° C, 90m ^Three / Day When the liquid A to be treated is heated to 135 ° C. with the heater 2 and held for 90 seconds, the heat transfer area of the preheaters 6 and 7 is 45 m. ² , Heat transfer area of heater 2 is 8m ² Then, the liquid A to be treated is heated to 75 ° C. by the pre-stage preheater 6, raised to 120 ° C. by the post-stage preheater 7, and becomes 135 ° C. by the heater 2. Further, the treated liquid E discharged from the holding means 3 is cooled to 90 ° C. by the rear stage preheater 7 and is lowered to 45 ° C. by the front stage preheater 6. In this case, it is sufficient to put 300 kg / hour of heat medium (steam) at a steam pressure of 4 KG in the heater 2.
[0035]
On the other hand, 90m ^Three / Day When liquid A to be treated is sterilized at 135 ° C for 90 seconds using a kill tank (direct steam input sealed container) or a single direct heat exchanger, the required steam volume is 2,200 kg. / It becomes time. Furthermore, in this case, in order to lower the temperature of the treated liquid E after passing through the holding means 3, it is necessary to separately add temperature-decreasing energy or to take time and space for temperature-decreasing. From this, it has been confirmed that by providing the preheaters 6 and 7 as in the present invention, it is possible to save energy by saving energy supplied from the outside.
[0036]
The present invention can be applied to the case where the preheater is a single heat exchanger, but it is necessary to increase the heat transfer surface when the temperature of the liquid A to be treated at 30 ° C is increased to 120 ° C with one heat exchanger. If the heat transfer surface becomes large, drift is likely to occur, and the drift causes uneven temperature distribution of the liquid A to be treated. Occurrence of uneven temperature distribution of the liquid A to be treated in heat sterilization is not preferable because a portion that cannot be heated to the sterilization temperature may be generated.
[0037]
In the heat exchanger in which the same amount of the high temperature fluid flows as the low temperature fluid, the present inventor has the rising temperature of the low temperature fluid or the decreasing temperature of the high temperature fluid with respect to the temperature difference ΔT1 between the inlet temperature of the low temperature fluid and the outlet temperature of the high temperature fluid. It was experimentally found that when the ratio (ΔT2 / ΔT1) of ΔT2 (exchange temperature difference) is larger than 4, the temperature distribution unevenness is likely to occur. For example, when the preheater in FIG. 1 is a single heat exchanger, the exchange temperature difference ΔT2 (the rising temperature of the liquid A to be processed which is a low temperature fluid or the falling temperature of the processed liquid E which is a high temperature fluid) is 90 ° C. = 120 ° C-30 ° C), and the temperature difference ΔT1 between the inlet temperature of the liquid A to be processed which is a low temperature fluid and the outlet temperature of the processed liquid E which is a high temperature fluid is 15 ° C (45 ° C-30 ° C). Therefore, the ratio ΔT2 / ΔT1 is 6 (= 90/15), and there is a concern about the occurrence of uneven temperature distribution.
[0038]
In the embodiment of FIG. 1, multistage heat exchangers in which heat exchangers into which a low temperature fluid and the same amount of high temperature fluid flow are connected in series are preheaters 6 and 7, and the ratio ΔT2 / ΔT1 in each heat exchanger is The occurrence of uneven temperature distribution in the liquid A to be treated is prevented by setting it to 4 or less, preferably about 3. That is, in the pre-stage preheater 6 of FIG. 1, the exchange temperature difference ΔT2 is 45 ° C. (= 75 ° C.-30 ° C.), and the temperature difference ΔT 1 between the low temperature fluid inlet temperature and the high temperature fluid outlet temperature is 15 ° C. (45 ° C.-30 Therefore, the ratio ΔT2 / ΔT1 is 3 (= 45/15). In the second stage preheater 7, the exchange temperature difference ΔT2 is 45 ° C. (= 120 ° C.-75 ° C.), and the temperature difference ΔT 1 between the low temperature fluid inlet temperature and the high temperature fluid outlet temperature is 15 ° C. (90 ° C.-75 ° C.). Therefore, the ratio ΔT2 / ΔT1 is 3 (= 45/15). By preventing the occurrence of uneven temperature distribution in the liquid A to be treated, it is possible to prevent the occurrence of a portion that cannot be heated to the sterilization temperature.
[0039]
Although there is no restriction | limiting in particular in the heat exchanger used as the heater 2 in FIG. 1, and the preheaters 6 and 7, For example, it can be set as a spiral type heat exchanger. The spiral heat exchanger has a single flow path and is smoother than the multi-tube heat exchanger. For this reason, when a scale adheres in the pipe of the heat exchanger, the cross-sectional area of the adhering portion decreases, thereby increasing the flow velocity, and the self-purifying action for peeling the scale works. Therefore, the use of a spiral heat exchanger can be expected to provide an apparatus that is difficult to scale and easy to maintain.
[0040]
Further, in the embodiment of FIG. 1, a pH adjusting device 32 is provided in the storage tank 19 of the liquid A to be processed to be sent to the heater 2, and the liquid A is sterilized by sterilized proteins and other organic substances of microorganisms and / or viruses. By setting the pH so that it does not precipitate even after denaturation, protein precipitation in the infusion route is suppressed. Further, as a countermeasure when protein or inorganic scale or the like is deposited or adhered in the infusion channel, a valve V8 is provided between the drainage channel 13 and the feeding channel 11 of the treated liquid E after passing through the preheaters 6 and 7. The line washing unit 16 is connected via V9 and V10. When the infusion path consisting of the inlet path 11, the sterilization path 4, the discharge path 12, and the preheating devices 6 and 7 is cleaned, the closed flow consisting of the infusion path and the line cleaning unit 16 is switched by switching the valves V8, V9 and V10. Form a road.
[0041]
For example, before or when sterilization is started or interrupted, the line cleaning unit 16 is connected to the inlet path 11 by closing the on-off valve V3 and opening the valve V10, and the switching means V8 and V9 are switched to the cleaning path 15 side. The infusion channel is washed by circulating a scale remover and other chemicals through the closed channel. An example of the switching means V8, V9 is also a pair of on-off valves or switching valves. Preferably, the infusion channel is made of stainless steel and nitric acid is circulated. Nitric acid dissolves the scale and forms a passive film on the stainless steel pipe to increase the corrosion resistance. By forming a passive film, it can be expected that the apparatus has a long life. However, the chemical solution is not limited to nitric acid, and other suitable acid or alkali can be used.
[0042]
The line cleaning unit 16 may be a prior art CIP unit that distributes a sufficient amount of a suitable temperature of cleaning liquid or vapor to any part of the infusion path. When the heater 2 is a heat exchanger, all the infusion channels and devices are heated and sterilized (Sterilization-in-place) by introducing the outlet steam of the heater 2 to the line cleaning unit 16 and reusing it. , SIP) is possible. By simple sterilization using not only chemicals but also steam, the frequency of equipment open inspections can be reduced and maintenance can be further facilitated.
[0043]
【The invention's effect】
As described in detail above, the method and apparatus for heat sterilization of a liquid to be processed according to the present invention is to heat the liquid to be sterilized with a heater and hold it for a required time with a holding means and preheat the processed liquid after holding. In heat sterilization used for preheating the liquid to be treated before heating by heating, a sampling path is connected between the holding means and the preheater via the switching means, and when the temperature at the outlet of the heater is detected as insufficient, Since the inflow of the processing liquid is stopped and the switching means is switched to the extraction path side and the residual liquid in the heater and the holding means is extracted, the following remarkable effects are obtained.
[0044]
(A) Since the liquid to be treated that is not sufficiently sterilized can be prevented from flowing out to the lower flow path of the sterilization apparatus, contamination by microorganisms and / or viruses in the lower flow path can be surely prevented.
(B) The extracted residual liquid can be returned to the storage tank of the liquid to be treated before heating and re-sterilized easily.
(C) Insufficient sterilization by injecting the liquid to be treated at the initial flow rate at the sterilization temperature at the heater outlet and combining with the flow rate control of the liquid to be treated to increase the flow rate in response to the temperature rise at the heater outlet. The liquid to be processed can be continuously processed while preventing the generation of the liquid to be processed as much as possible.
(D) A large amount of liquid to be processed can be continuously processed, and a space-saving and compact apparatus can be obtained.
[0045]
(E) By setting the liquid to be treated to a pH at which no protein precipitates, it is possible to continuously treat a large amount of the liquid to be treated while avoiding clogging of piping.
(F) When removing the residual liquid with the washing liquid introduced via the heater, it is possible to avoid precipitation of the protein at the time of extraction by setting the washing liquid to a pH at which the protein does not precipitate.
(G) Since the high-temperature treated liquid is used for preheating the liquid to be treated before heating, it is possible to save energy by reducing the energy supplied from the outside as compared with a batch heat treatment method such as direct steam injection.
[0046]
(H) Since sterilization is performed by heat treatment, bacteria and viruses that cannot be sufficiently sterilized by a chemical solution can be reliably inactivated by adjusting the sterilization temperature and time.
(I) There is less risk of polluting the environment than sterilization with chemicals. Moreover, since the medicine cost can be reduced, the running cost can be greatly reduced.
(N) For example, it is possible to arbitrarily change the sterilization temperature (inactivation temperature) by changing the steam pressure, and it is possible to easily deal with sterilization of waste water containing unknown bacteria and viruses in the future.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the apparatus of the present invention.
FIG. 2 is an example of a flow diagram illustrating the method of the present invention.
FIG. 3 is an explanatory view of a conventional sterilization apparatus.
[Explanation of symbols]
1 ... Sterilizer 2 ... Heater
3 ... Holding means 4 ... Sterilization path
5 ... Feeding means 6 ... Pre-stage preheater
7 ... latter stage preheater 8 ... temperature detector
9 ... Pressure detector 10 ... Extraction means
11 ... Incoming and outgoing route 12 ... Discharging route
13 ... Drainage path 14 ... Drainage path
15 ... Cleaning path 16 ... Line cleaning unit
17 ... Cleaning tank 18 ... Drainage reservoir
19 ... Storage tank 20 ... Flow control means
31 ... Raw water receiving tank 32 ... pH adjuster
33 ... Heat exchanger 34 ... Heat exchanger
35 ... Holding tube
36… Temperature sensor 37… Pressure sensor
38 ... Water pipe 39 ... Infusion pump
40 ... Temperature sensor 41 ... Water discharge pipe
42 ... Preheating device 43 ... Preheating device
44… Pipe cleaning unit 45… Valve
46 ... Valve
A ... Processed liquid E ... Processed liquid
G ... Heat medium I ... Cleaning liquid
A '... Wastewater containing microorganisms and / or viruses
B '... Temperature drainage C' ... Temperature drainage
D '... High temperature drainage E' ... Sterilized drainage
F '... Low temperature drainage G' ... Steam
H '... treated water

Claims (12)

In a heat sterilization method in which a liquid to be treated is heated to a sterilization temperature by a heater and held for a required time by a holding means, and the treated liquid after holding is guided to a preheater and used for preheating the liquid to be processed before heating. A drainage path communicating with the waste liquid reservoir between the heater and the preheater via the switching means, and when the temperature of the outlet of the heater is detected to be insufficient, the flow of the liquid to be treated into the heater is stopped and the switching means is connected to the drainage path side. A method for heat sterilization of the liquid to be processed, which is obtained by switching to, extracting the residual liquid in the heater and holding means to the drainage reservoir, returning the switching means to resume the flow of the liquid to be processed into the heater when sterilization is resumed. 2. The heat sterilization method according to claim 1, wherein the residual liquid is pushed out to a drainage reservoir by a cleaning liquid introduced via a heater when temperature shortage at the heater outlet is detected. 3. The heat sterilization method according to claim 1 or 2, wherein at the start or restart of inflow of the liquid to be treated or the cleaning liquid into the heater, the inflow liquid is caused to flow at an initial flow rate at a sterilization temperature at the heater outlet, and the liquid at the heater outlet is A method for heat sterilization of a liquid to be processed, wherein the flow rate of the liquid to be processed or the cleaning liquid is controlled so that the temperature becomes a sterilization temperature. 4. The heat sterilization method for a liquid to be treated according to claim 1, wherein the liquid to be treated or the washing liquid is allowed to flow into a heater at a pH at which the protein does not precipitate. The heat sterilization method according to any one of claims 1 to 4, wherein the waste liquid reservoir is used as a storage tank for the liquid to be processed before the heating. A heater that heats the liquid to be treated to a sterilization temperature, an on-off valve provided in an inflow path of the liquid to be treated that communicates with an inlet of the heater, and a liquid to be treated at a sterilization temperature that communicates with an outlet of the heater Holding means for holding, preheater for raising the temperature of the liquid to be processed before the treatment with the processed liquid after passing through the holding means, connected to the drainage reservoir via a switching means between the holding means and the preheater An extraction path, a temperature detector for detecting the liquid temperature at the heater outlet, and closing the on-off valve when the temperature detector detects a temperature shortage, and switching the switching means to the extraction path side so that the inside of the heater and the holding means A heat sterilization apparatus for a liquid to be treated, which is provided with extraction means for extracting the residual liquid of the liquid into a waste liquid reservoir. 7. The heat sterilization apparatus according to claim 6, wherein a cleaning liquid tank is provided in the inlet passage through a cleaning liquid valve, and the residual liquid is drained by the cleaning liquid that is opened by opening the cleaning liquid valve and detecting the temperature shortage. A device for heat sterilization of the liquid to be treated, which is extruded into a liquid reservoir. 8. The heat sterilization apparatus according to claim 6 or 7, wherein the inflow liquid flows into the inlet passage at an initial flow rate at a sterilization temperature at the outlet of the heater at the start or resumption of inflow of the liquid to be treated or the cleaning liquid into the heater. And a heat sterilization apparatus for the liquid to be processed, provided with a flow rate control means for controlling the flow rate of the liquid to be processed or the cleaning liquid so that the liquid temperature at the outlet of the heater becomes the sterilization temperature. The heat sterilization apparatus for a liquid to be treated according to any one of claims 6 to 8, further comprising a pH adjusting apparatus for adjusting the liquid to be treated or the cleaning liquid to be sent to the heater to a pH at which protein does not precipitate. The heat sterilization apparatus according to any one of claims 6 to 9, wherein the liquid sterilization apparatus serves as a liquid storage tank for the liquid to be processed which communicates the residual liquid reservoir with the feeding path. The heat sterilizer according to any one of claims 6 to 10, wherein the preheater is a heat exchanger into which a treated liquid and an amount of liquid to be treated flow, or a multistage heat exchanger in which the heat exchanger is connected in series A heat sterilization apparatus for the liquid to be treated. 12. The heat sterilization apparatus according to claim 11, wherein the ratio of the rise temperature of the liquid to be treated or the fall temperature ΔT2 of the liquid to be treated to the temperature difference ΔT1 between the inlet temperature of the liquid to be treated and the outlet temperature of the liquid to be treated in each heat exchanger ( An apparatus for heat sterilization of a liquid to be treated with ΔT2 / ΔT1) of 4 or less.

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