JP5000042B2

JP5000042B2 - Dynamic ice heat storage system and its operation method and prediction method

Info

Publication number: JP5000042B2
Application number: JP2001041633A
Authority: JP
Inventors: 明彦岡村; 由行小澤; 正幸谷野
Original assignee: Takasago Thermal Engineering Co Ltd
Current assignee: Takasago Thermal Engineering Co Ltd
Priority date: 2001-02-19
Filing date: 2001-02-19
Publication date: 2012-08-15
Anticipated expiration: 2021-02-19
Also published as: JP2002243216A

Description

【０００１】
【発明の属する技術分野】
本発明は，ダイナミック型氷蓄熱槽システム及びその運転方法に関する。
【０００２】
【従来の技術】
氷の融解潜熱を利用して冷熱をより小さい蓄熱槽に蓄える氷蓄熱システムが普及している。製氷方式の氷蓄熱システムには，蓄熱槽内の伝熱管の廻りにブロック状の氷を製造し，製氷過程，蓄氷過程，解氷過程を同一の蓄熱槽内で行うスタティック型氷蓄熱システムと，蓄熱槽外の製氷機で製造した氷・水スラリーを蓄熱槽に供給するダイナミック型氷蓄熱システムがあり，スタティック型氷蓄熱システムは，ビル空調システムの熱源機器や，工場での製造プロセスの冷却などで採用されている。一方，ダイナミック型氷蓄熱システムは，近年では，ビル空調システムの熱源機器などに採用されている。
【０００３】
一般に，製造プロセスの冷却では，ビル空調システムと比べて，低温の冷水を連続（例えば２４時間運転など）して供給する必要がある。特に食品や医薬品，半導体その他の電子部品等の製造プロセスなどにあっては，先鋭的で大きな冷却負荷（ピーク的な冷却負荷）が発生した場合においても，常に０℃近くの低温の冷水を供給することが要求される。このように低温の冷水を昼夜通して連続して供給する場合，蓄熱槽内の水を昇温させる解氷工程と蓄熱槽内の水を冷却する製氷工程とが同時に行われることになる。
【０００４】
ここで，スタティック型氷蓄熱システムにおいて，このように解氷工程と製氷工程とが同時になされた場合，スタティック型氷蓄熱システムでは，氷の成長と融解が限定された伝熱管の廻りで行われるので，蓄熱槽内での熱源水（水）を冷却する能力は，伝熱管の表面積あるいは氷の表面積に限定されてしまう。このためスタティック型氷蓄熱システムでは，先鋭的で大きな熱負荷に対しては，０℃近くの低温の冷水を連続して得ることが難しくなる。
【０００５】
【発明が解決しようとする課題】
一方，ダイナミック型氷蓄熱システムでは，蓄熱槽外で製造した氷・水スラリーを供給した蓄熱槽内にシャーベット状の氷を蓄えるので，製氷工程と解氷工程が分離されている。空調用途の一般的なダイナミック型氷蓄熱システムでは，製氷工程と解氷工程が同時には行われないのが通常であるが，仮にダイナミック型氷蓄熱システムにおいてそれらの工程が同時になされた場合，蓄熱槽内の氷融解に係わりなく，氷・水スラリーを蓄熱槽に供給でき，より先鋭的で大きな熱負荷に対しても，０℃近くの低温の冷水を連続して得ることが可能になる。ところが，ダイナミック型氷蓄熱システムにおいて，このように製氷工程と解氷工程を同時に行った場合，電力などのエネルギー費が高い日中に製氷工程を行うことが回避し難くなる。
【０００６】
従って本発明の目的は，製氷コストをなるべく少なく抑えつつ，先鋭的で大きな熱負荷が発生しても，０℃近くの低温の冷水を連続して得ることが可能なダイナミック型氷蓄熱システム及びその運転方法を提供することにある。
【０００７】
【課題を解決するための手段】
この目的を達成するために，本発明によれば，氷を蓄える蓄熱槽と，蓄熱槽から取水した水を冷却し，氷・水スラリーにして蓄熱槽に供給する製氷サイクルと，蓄熱槽から取水した水を熱交換し，昇温した水を蓄熱槽に戻す解氷サイクルと，蓄熱槽から製氷サイクルへの取水を制御する制御装置を備え，製氷サイクルで製造した氷・水スラリーを蓄熱槽に供給して蓄熱し，解氷サイクルで製造プロセスの冷却負荷を冷却するダイナミック型氷蓄熱システムであって，制御装置は，予め設定された製造プロセスの冷却負荷の時間的変化と蓄熱槽内に浮遊している氷の融解熱量に基づいて，蓄熱槽から取水される水の温度を製造プロセスの冷却負荷の運転終了まで演算し，該演算される水の温度が製造プロセスの冷却負荷の運転終了まで所定の上限温度に達しない範囲で，製氷サイクルの運転を停止可能な最大時間Ｘを求め，この最大時間Ｘの間，製氷サイクルの運転を停止させる制御を行うことを特徴とする，ダイナミック型氷蓄熱システムが提供される。
【０００８】
また本発明によれば，氷を蓄える蓄熱槽と，蓄熱槽から取水した水を冷却し，氷・水スラリーにして蓄熱槽に供給する製氷サイクルと，蓄熱槽から取水した水を熱交換し，昇温した水を蓄熱槽に戻す解氷サイクルとを備え，製氷サイクルで製造した氷・水スラリーを蓄熱槽に供給して蓄熱し，解氷サイクルで製造プロセスの冷却負荷を冷却するダイナミック型氷蓄熱システムの運転方法であって，予め設定された製造プロセスの冷却負荷の時間的変化と蓄熱槽内に浮遊している氷の融解熱量に基づいて，蓄熱槽から取水される水の温度を製造プロセスの冷却負荷の運転終了まで演算し，該演算される水の温度が製造プロセスの冷却負荷の運転終了まで所定の上限温度に達しない範囲で，製氷サイクルの運転を停止可能な最大時間Ｘを求める工程と，この最大時間Ｘの間，製氷サイクルの運転を停止させる工程を有し，蓄熱槽から取水した水を製氷サイクルにおいて氷・水スラリーにして蓄熱槽に供給する工程と，蓄熱槽から取水した水を解氷サイクルにおいて熱交換して昇温した水を蓄熱槽に戻す解氷工程を，時期的に重複して行うことを特徴とする，ダイナミック型氷蓄熱システムの運転方法が提供される。
【０００９】
この運転方法にあっては，最大時間Ｘが所定の下限停止時間（たとえば，冷凍機の再起動防止タイマーの時間）を超えていない場合は，製氷サイクルの運転を停止させないものであっても良い。
【００１０】
本発明によれば，変化する製造プロセスの冷却負荷の要求に対し冷熱の供給が下回ることはなく，製氷サイクルの運転時間を短縮しつつ，製造プロセスの冷却負荷の運転終了まで，水の温度を所定の上限温度に達しない範囲に制御でき，製造プロセスの冷却負荷に対して所定の温度以下に冷却した熱媒を運転終了まで供給することが可能となる。
また本発明によれば，氷を蓄える蓄熱槽と，蓄熱槽から取水した水を冷却し，氷・水スラリーにして蓄熱槽に供給する製氷サイクルと，蓄熱槽から取水した水を熱交換し，昇温した水を蓄熱槽に戻す解氷サイクルとを備え，製氷サイクルで製造した氷・水スラリーを蓄熱槽に供給して蓄熱し，解氷サイクルで製造プロセスの冷却負荷を冷却するダイナミック型氷蓄熱システムを運転するにあたり，予め設定された製造プロセスの冷却負荷の時間的変化と蓄熱槽内に浮遊している氷の融解熱量に基づいて，蓄熱槽から取水される水の温度を製造プロセスの冷却負荷の運転終了まで演算し，該演算される水の温度が製造プロセスの冷却負荷の運転終了まで所定の上限温度に達しない範囲で，製氷サイクルの運転を停止可能な最大時間Ｘを求めることを特徴とする，ダイナミック型氷蓄熱システムにおける最大時間Ｘの予測方法が提供される。
【００１１】
【発明の実施の形態】
以下，本発明の好ましい実施の形態を図面を参照にして説明する。図１に示されるように，本発明の実施の形態にかかるダイナミック型氷蓄熱システム１（以下，「氷蓄熱システム１」）において，蓄熱槽１０の内部に水１１が充填されている。また，この蓄熱槽１０の内部の水１１に，次に説明する製氷サイクル２０によって生成されたシャーベット状の氷１２が蓄えられている。蓄熱槽１０の底部には温度センサー１３が装着されており，蓄熱槽１０内の水１１の温度Ｔ１が，この温度センサー１３によって検知されている。
【００１２】
製氷サイクル２０は，蓄熱槽１０の下部（底部または氷の存在しない範囲の下方）から取水する製氷取水管２１と，この製氷取水管２１に設けられたポンプ２２の稼働によって蓄熱槽１０から取水した水１１を予熱する予熱器２３と，この予熱器２３による予熱後において，水１１を氷点下温度まで冷却させる製氷のための過冷却器２４を備えている。製氷取水管２１には，流量センサー２５と温度センサー２６が装着されており，製氷取水管２１によって送液される水１１の流量Ｆ１が流量センサー２５によって検知され，予熱器２３を経て過冷却器２４に送液される水１１の温度Ｔ２が，温度センサー２６によって検知されている。
【００１３】
予熱器２３には，冷却負荷の一例としての製造プロセス３０との間で熱媒水を循環させる熱媒循環回路３１が導入されている。予熱器２３においては，こうして熱媒循環回路３１を経て製造プロセス３０に循環供給される熱媒水と，製氷取水管２１を送液される水１１とが熱交換を行い，熱媒水は冷却され，水１１は加熱される。これにより，製造プロセス３０には予熱器２３にて冷却された熱媒水が循環供給され，過冷却器２４には予熱器２３にて加熱された水１１が供給される。
【００１４】
過冷却器２４には，冷凍機４０で冷却されたブライン（不凍液）が，ポンプ４１の稼働によって，ブライン往管４２及びブライン還管４３を経て循環供給されている。冷凍機４０は，ブラインを氷点下温度まで冷却するための冷凍機凝縮器や冷却塔などを備える。
【００１５】
過冷却器２４では，製氷取水管２１を経て供給された水１１を，ブラインの冷熱により−２〜−３℃の過冷却状態に冷却させる。こうして過冷却状態に冷却させられた水１１が過冷却器２４から吐出され，過冷却解除パイプ４５において水の状態から氷の状態に相変化し，氷・水スラリーとなって蓄熱槽１０内に供給されるようになっている。これにより，蓄熱槽１０の内部には，水１１にシャーベット状の氷１２が蓄えられた状態となる。
【００１６】
冷凍機４０から過冷却器２４にブラインを送液するブライン往管４２には，流量センサー４６と温度センサー４７が装着されており，ブライン往管４２に送液されるブラインの流量Ｆ２が流量センサー４６によって検知され，過冷却器２４に送液されるブラインの温度Ｔ３が，温度センサー４７によって検知されている。ブライン還管４３には，温度センサー４８が装着されており，ブライン還管４３を経て冷凍機４０に戻されるブラインの温度Ｔ４が，温度センサー４８によって検知されている。
【００１７】
解氷サイクル５０は，蓄熱槽１０の下方から冷水を取水する解氷取水管５１と，この解氷取水管５１に設けられ，蓄熱槽１０から水１１を取水して冷熱を負荷に供するためのポンプ５２と，製造プロセス３０の熱媒水を水１１と熱交換させる冷却器５３を備えている。なお，取水を直接製造プロセス３０に供給するシステムであっても良い。その場合，水１１と例えば飲料を直接熱交換する熱交換器が冷却器５３に該当する。解氷取水管５１には，流量センサー５５と温度センサー５６が装着されており，解氷取水管５１によって送液される水１１の流量Ｆ３が流量センサー５５によって検知され，水１１の温度Ｔ５が，温度センサー５６によって検知されている。
【００１８】
冷却器５３には，製造プロセス３０との間で熱媒水を循環させる熱媒循環回路３２が導入されている。冷却器５３においては，こうして熱媒循環回路３２を経て製造プロセス３０に循環供給される熱媒水と，解氷取水管５１を送液される水１１とが熱交換を行い，熱媒水は冷却され，水１１は加熱される。これにより，製造プロセス３０には冷却器５３にて冷却された熱媒水が循環供給され，冷却器５３にて加熱された水１１は，解氷取水管５１から蓄熱槽１０の上方に再び戻される。昇温した水１１は槽内の氷１２を解氷する。
【００１９】
製造プロセス３０は，往ヘッダ３５と還ヘッダ３６を備えている。前述のように予熱器２３から熱媒循環回路３１を経て供給された熱媒水と冷却器５３から熱媒循環回路３２を経て供給された熱媒水は，往ヘッダ３５で合流された後，供給管３７によって製造プロセス３０の所望の場所に適宜供給されている。一方，製造プロセス３０の各箇所から戻り管３８を経て戻された熱媒水は，還ヘッダ３６で合流された後，先に説明した熱媒循環回路３１及び熱媒循環回路３２を経て予熱器２３と冷却器５３に分配されて戻される。
【００２０】
製造プロセス３０は，例えば飲料や薬品原料などの冷却が必要なものであり，製造プロセス３０には，常に０℃近くの低温の冷水を供給することが要求されている。製造プロセス３０において要求される冷却負荷の時間的変化は予め設定されており，この氷蓄熱システム１に備えられた制御装置６０に入力されている。また，先に説明した温度センサー１３によって検知された水１１の温度Ｔ１，温度センサー２６によって検知された水１１の温度Ｔ２，温度センサー４７によって検知されたブラインの温度Ｔ３，温度センサー４８によって検知されたブラインの温度Ｔ４，温度センサー５６によって検知された水１１の温度Ｔ５と，流量センサー２５によって検知された水１１の流量Ｆ１，流量センサー４６によって検知されたブラインの流量Ｆ２，流量センサー５５によって検知された水１１の流量Ｆ３が，制御装置６０にそれぞれ入力されている。後に説明するように，制御装置６０は，こうして入力された冷却負荷の時間的変化と，各温度Ｔ１，Ｔ２，Ｔ３，Ｔ４，Ｔ５，流量Ｆ１，Ｆ２，Ｆ３に基づいて演算を行い，製氷サイクル２０において製氷取水管２１に設けられたポンプ２２，冷凍機４０及びポンプ４１の稼働を制御するようになっている。なお，取水される水の温度は予熱器側，冷却器側で同じ温度であり，温度センサーは符号２６，４７のいずれか一方のものであってもかまわない。
【００２１】
さて，以上のように構成された氷蓄熱システム１において，製氷サイクル２０にあっては，ポンプ２２の稼働により，蓄熱槽１０の下部から取水された水１１が製氷取水管２１を経て，予熱器２３，過冷却器２４の順に送液される。そして，予熱器２３では，熱媒循環回路３１を送液される熱媒水と熱交換を行うことにより，水１１は氷点を超える温度（例えば約０．５℃程度）まで加熱され，過冷却器２４まで送液される（なお，取水温度が例えば約０．５℃以上の場合は，加熱されない）。過冷却器２４では，こうして供給される水１１を，冷凍機４０からブライン往管４２及びブライン還管４３を経て循環供給されるブラインの冷熱により，−２〜−３℃の過冷却状態に安定して冷却させる。こうして過冷却状態に冷却させられた水１１が過冷却器２４から吐出され，過冷却解除パイプ４５において水の状態から氷の状態に相変化し，氷・水スラリーとなって蓄熱槽１０内に供給する。こうして，蓄熱槽１０の内部には，水１１にシャーベット状の氷１２が充填された状態となる。また，予熱器２３において水１１と熱交換をしたことにより冷却された熱媒水は熱媒循環回路３１を経て製造プロセス３０に循環供給される。
【００２２】
一方，解氷サイクル５０にあっては，ポンプ５２の稼働により，蓄熱槽１０の底部から取水された水１１が，解氷取水管５１を経て冷却器５３に送液される。そして，冷却器５３では，熱媒循環回路３２を送液される熱媒水と熱交換を行うことにより水１１は加熱され，こうして昇温した状態となって水１１は，解氷取水管５１から蓄熱槽１０の上方に再び戻される。また，冷却器５３において水１１と熱交換をしたことにより冷却された熱媒水は熱媒循環回路３２を経て製造プロセス３０に循環供給される。
【００２３】
こうして，製造プロセス３０には，予熱器２３及び冷却器５３にて冷却された熱媒水が供給されることとなり，製造プロセス３０に対して，常に０℃近くの低温の冷水を供給することが可能となる。
【００２４】
ここで，以上のように構成された氷蓄熱システム１にあっては，製造プロセス３０において要求される冷却負荷の時間的変化は予め設定されており，この冷却負荷の時間的変化は制御装置６０に入力されている。図２に示すように，先ず氷蓄熱システム１が起動されると（Ｓ１），制御装置６０には，温度センサー１３によって検知された水１１の温度Ｔ１，温度センサー２６によって検知された水１１の温度Ｔ２，温度センサー４７によって検知されたブラインの温度Ｔ３，温度センサー４８によって検知されたブラインの温度Ｔ４，温度センサー５６によって検知された水１１の温度Ｔ５と，流量センサー２５によって検知された水１１の流量Ｆ１，流量センサー４６によって検知されたブラインの流量Ｆ２，流量センサー５５によって検知された水１１の流量Ｆ３が，それぞれ入力される（Ｓ２）。
【００２５】
次に制御装置６０は，こうして入力された各温度Ｔ１，Ｔ２，Ｔ３，Ｔ４，Ｔ５，流量Ｆ１，Ｆ２，Ｆ３に基づいて演算を行い，先ず，蓄熱槽１０に残っている残蓄熱量（冷熱量）を求める（Ｓ３）。ここで，蓄熱槽１０に残っている残蓄熱量（冷熱量）の時間的変化は，蓄熱槽１０への冷熱の単位時間あたりの供給量と，蓄熱槽１０からの冷熱の単位時間あたりの取り出し量（「製造プロセス３０の熱媒水に供給される単位時間あたりの冷熱量」に等しい）との差として表すことができる。そして，このように表される時間的変化を経時的に積算（積分）することにより，蓄熱槽１０に残っている残蓄熱量（冷熱量）を求める。
【００２６】
なお，蓄熱槽１０に残っている残蓄熱量（冷熱量）を求めるにあたり，蓄熱槽１０への冷熱の単位時間あたりの供給量は，冷凍機４０からブライン往管４２を経て過冷却器２４に供給されるブラインの温度Ｔ３と，過冷却器２４からブライン還管４３を経て冷凍機４０に戻されるブラインの温度Ｔ４との温度差Ｔ３−Ｔ４及びブライン往管４２及びブライン還管４３を送液されるブラインの流量Ｆ２に基づいて，ブラインの比熱及び比重を考慮して求めることができる。蓄熱槽１０からの冷熱の単位時間あたりの取り出し量は，予熱器２３によって水１１から取り出される単位時間あたりの冷熱量と，冷却器５３によって水１１から取り出される単位時間あたりの冷熱量の和である。予熱器２３によって水１１から取り出される単位時間あたりの冷熱量は，蓄熱槽１０内の水１１の温度Ｔ１と過冷却器２４に送液される水１１の温度Ｔ２との差Ｔ１−Ｔ２及び製氷取水管２１を送液される水１１の流量Ｆ１に基づいて，水１１の比熱及び比重を考慮して求めることができる。冷却器５３によって水１１から取り出される単位時間あたりの冷熱量は，蓄熱槽１０内の水１１の温度Ｔ１と冷却器５３から蓄熱槽１０に戻される水１１の温度Ｔ５との差Ｔ１−Ｔ５及び解氷取水管５１を送液される水１１の流量Ｆ３に基づいて，水１１の比熱及び比重を考慮して求めることができる。
【００２７】
こうして蓄熱槽１０に残っている残蓄熱量（冷熱量）を求めた後，次に制御装置６０は，前述のように予め設定された製造プロセス３０において要求される冷却負荷の時間的変化に基づいて，蓄熱槽１０から取水される水の温度Ｔ１（蓄熱槽１０内の水１１の温度Ｔ１に等しい）を，冷却負荷である製造プロセス３０の運転終了まで演算する。こうして，演算された水１１の温度Ｔ１が冷却負荷である製造プロセス３０の運転終了まで所定の上限温度に達しない範囲で，製氷サイクル２０の運転を停止可能な最大時間Ｘを求める（Ｓ４）。
【００２８】
ここで，最大時間Ｘは次のようにして求められる。即ち，図３に示すように，先ず，最初に最大時間Ｘ＝０と仮定する（Ｓ１０）。なお，最大時間Ｘ＝０とは，製氷サイクル２０の運転を停止せずに，製造プロセス３０の運転終了まで製氷サイクル２０を連続運転させる状態を意味する。こうして先ず最大時間Ｘ＝０と仮定して，蓄熱槽１０から取水される水の温度Ｔ１を，製造プロセス３０の運転終了まで演算する（Ｓ１１）。
【００２９】
ここで，蓄熱槽１０から取水される水の温度Ｔ１の時間的変化ｄＴ１／ｄｔは，次式（１）によって表すことができる。
Ｃ・ρ・η・Ｖ’（ｄＴ１／ｄｔ）＝Ｑ１−Ｑ２ …（１）
【００３０】
この式（１）において，Ｑ１は，予め制御装置６０に設定されている冷却負荷の時間的変化である。Ｑ２は，蓄熱槽１０内に浮遊している氷１２の融解熱量である。Ｃは，水の比熱である。ρは，水の比重である。Ｖ’は蓄熱槽１０内にあるシャーベット状の氷１２以外の水１１の領域の容積を示し，Ｖ’＝Ｖ・ηである。Ｖは，蓄熱槽１０の容積である。ηは，蓄熱の利用率を示し，η＝１−（残蓄熱量／最大蓄熱量）である。なお，Ｑ２は別途の実験整理式（蓄熱槽の寸法，運転条件（Ｔ５，Ｆ３），ηなどの関数）から求めることができる。
【００３１】
そして，このように表される時間的変化（ｄＴ１／ｄｔ）を経時的に積算（積分）することにより，蓄熱槽１０から取水される水１１の温度Ｔ１を，製造プロセス３０の運転終了まで演算する。
【００３２】
なお，実際には過冷却解除パイプ４５から蓄熱槽１０内には氷・水スラリーが供給されており，図４に模式的に示すように，蓄熱槽１０内には氷１２が浮遊している氷層６５の部分と，過冷却解除パイプ４５から落下した水１１が蓄熱槽１０内において氷１２に接触せずに，蓄熱槽１０の下部まで流れるバイパス部分６６が存在する。この図４に示す計算モデルにおいては，蓄熱槽１０から取水される水の温度Ｔ１の時間的変化ｄＴ１／ｄｔは，次式（２）によって表すことができる。
Ｃ・ρ・Ｖ’・（ｄＴ１／ｄｔ）＝Ｃ・ρ・Ｆ３・Ｔｂ＋Ｃ・ρ・Ｆｂｗ・Ｔｂｗ−Ｃ・ρ・（Ｆ３＋Ｆｂｗ）・Ｔ１ …（２）
【００３３】
この式（２）において，Ｔｂは，氷層６５の融解で蓄熱槽１０の底部に形成される水域と氷層６５との境界温度である。Ｆｂｗは，バイパス部分６６を流れる水１１の流量である。Ｔｂｗは，過冷却解除パイプ４５から落下した水１１の温度（バイパス部分６６を流れる水１１の温度に等しい）である。なお，Ｔｂは，次式（３）のＱ２との関係から求めることができる。
Ｑ２＝Ｃ・ρ・Ｆ３・（Ｔｂ−Ｔ５） …（３）
【００３４】
そして，図４に示す計算モデルにおいて，こうして表される時間的変化（ｄＴ１／ｄｔ）を経時的に積算（積分）することにより，蓄熱槽１０から取水される水１１の温度Ｔ１を，製造プロセス３０の運転終了まで演算することができる。
【００３５】
こうして蓄熱槽１０から取水される水１１の温度Ｔ１を，製造プロセス３０の運転終了まで演算した後，図３に示すように，水１１の温度Ｔ１の温度が製造プロセス３０の運転終了までの間において，所定の上限温度未満であるか否かを判定する（Ｓ１２）。ここで，所定の上限温度は，製造プロセス３０の要求によって定められ，例えば飲料を冷却する製造プロセスなどにあっては，例えば１．５℃程度に定められる。
【００３６】
そして，このＳ１２の判定にて，製造プロセス３０の運転終了までの間において，水１１の温度Ｔ１の温度が常に所定の上限温度未満である場合は，最大時間Ｘ＝Ｘ＋ΔＸとする（Ｓ１３）。次に，このようにΔＸだけ増やした最大時間Ｘについて，先と同様に，再び蓄熱槽１０から取水される水の温度Ｔ１を，製造プロセス３０の運転終了まで演算する（Ｓ１１）。その後，水１１の温度Ｔ１の温度が製造プロセス３０の運転終了までの間において，所定の上限温度未満であるか否かを判定する（Ｓ１２）。こうして，製造プロセス３０の運転終了までの間において，水１１の温度Ｔ１の温度が常に所定の上限温度未満である限り，最大時間ＸをΔＸずつ増やし続ける。
【００３７】
一方，このＳ１２の判定にて，水１１の温度Ｔ１の温度が製造プロセス３０の運転終了までの間において，所定の上限温度以上となった場合は，最大時間Ｘを決定する（Ｓ１４）。この場合，最大時間Ｘは，水１１の温度Ｔ１の温度が所定の上限温度以上となる直前の時間とする。こうして，最大時間Ｘが求められる。
【００３８】
次に，図２に示すように，こうして求めた最大時間Ｘが所定の下限停止時間を越えているか否かを判定する（Ｓ５）。ここで，所定の下限停止時間は，冷凍機４０によって定められ，例えば冷凍機４０の再起動防止タイマーの値で定められる。
【００３９】
そして，このＳ５の判定にて，最大時間Ｘが所定の下限停止時間を越えている場合は，製氷サイクル２０の運転を停止させる（Ｓ６）。この場合，製氷取水管２１に設けられたポンプ２２，冷凍機４０及びポンプ４１の稼働を停止させることにより，製氷サイクル２０の運転を停止させる。なお，冷凍機４０に，上述したような下限停止時間がない場合は，このＳ５に示す判定は省略し，最大時間Ｘが０である場合を除いて，直ちに製氷サイクル２０の運転を停止させて良い。
【００４０】
こうして製氷サイクル２０の運転を停止させた後，先と同様に，制御装置６０は，その時点の各温度Ｔ１，Ｔ２，Ｔ３，Ｔ４，Ｔ５及び各流量Ｆ１，Ｆ２，Ｆ３に基づいて再び演算を行い，蓄熱槽１０に残っている残蓄熱量（冷熱量）を求める（Ｓ３）。その後，制御装置６０は，予め設定された製造プロセス３０において要求される冷却負荷の時間的変化に基づいて，蓄熱槽１０から取水される水の温度Ｔ１（蓄熱槽１０内の水１１の温度Ｔ１に等しい）を，冷却負荷である製造プロセス３０の運転終了まで再び演算し，水１の温度Ｔ１が冷却負荷である製造プロセス３０の運転終了まで所定の上限温度に達しない範囲で，製氷サイクル２０の運転を停止可能な最大時間Ｘを，先に図３で説明した工程に従って求める（Ｓ４）。そして，最大時間Ｘが所定の下限停止時間を越えているか否かを判定する（Ｓ５）。こうして，最大時間Ｘが所定の下限停止時間を越えなくなるまで，製氷サイクル２０の運転を停止させる。なお，冷凍機４０に，上述したような下限停止時間がない場合は，最大時間Ｘが０になるまで，製氷サイクル２０の運転を停止させる。
【００４１】
一方，Ｓ５の判定にて，最大時間Ｘが所定の下限停止時間を越えなくなった場合は，製氷サイクル２０の運転は停止させない。なお，冷凍機４０に，上述したような下限停止時間がない場合は，最大時間Ｘが０である場合，製氷サイクル２０の運転を停止させないようにする（なお，冷凍機４０に，上述したような下限停止時間を例えば別に設けた冷凍機の稼働や冷系統の冷熱などでまかなうなど，顧慮する必要のない場合で最大負荷がない場合は，最大時間Ｘが０である場合，製氷サイクル２０の運転を停止させないようにする）。
【００４２】
こうして製氷サイクル２０の運転を停止させない場合も，先と同様に，制御装置６０は，常にその時点の各温度Ｔ１，Ｔ２，Ｔ３，Ｔ４，Ｔ５及び各流量Ｆ１，Ｆ２，Ｆ３に基づいて再び演算を行い，蓄熱槽１０に残っている残蓄熱量（冷熱量）を求め（Ｓ３），以下同様に，水１の温度Ｔ１が冷却負荷である製造プロセス３０の運転終了まで所定の上限温度に達しない範囲で，製氷サイクル２０の運転を停止可能な最大時間Ｘを求める（Ｓ４）。こうして，最大時間Ｘが所定の下限停止時間を越えているか否かを判定するか（Ｓ５），もしくは最大時間Ｘが０になったか否かを判定し，製氷サイクル２０の運転を制御する。
【００４３】
こうして，図１で説明した氷蓄熱システム１は，製氷サイクル２０の運転時間を短縮しつつ，冷却負荷である製造プロセス３０の運転終了まで，水１の温度Ｔ１を所定の上限温度に達しない範囲に制御することができる。これにより，製造プロセス３０に対し，所定の温度以下に冷却した熱媒水を運転終了まで供給することが可能となる。必要十分な製氷がされるので省エネルギー的である。
【００４４】
以上，本発明の好ましい実施の形態の一例を説明したが，本発明はここで説明した形態に限定されない。例えば，冷却負荷の一例として食品などの製造プロセス３０を示して説明したが，本発明において冷却負荷はそのような製造プロセスに限られるものではなく，例えば空調（建物の冷房など）や他の熱源器（冷蔵，ショーケースの冷却，ケーブルトンネルの冷却）など，製造プロセス以外の冷却負荷について本発明を適用しても良い。
【００４５】
【実施例】
以下，本発明の実施例を説明する。図１で説明した氷蓄熱システムにおいて，本発明に従って運転を行った場合についてシミュレーションした。図５中の実線７０は，横軸を時間，左側の縦軸を単位時間あたりの冷却負荷として表した，一日における冷却負荷の変化を示している。製造プロセスの運転時間は０時から２２時過ぎまでで，２２時１５分以降から２４時には製造プロセスが運転されず，運転中は実線７０で示したように冷却負荷が変化すると想定した。また，製造プロセスの冷却負荷は連続的には発生せず，一時間の間にも３０分間程度の先鋭的な負荷の発生と，残りの３０分間程度の無負荷の状態があると想定した。蓄熱槽の大きさは１１×１４×２．２７ｍＨ（容積３５０ｍ^３）で，製氷サイクルの能力（製氷能力）は１２１０Ｍｃａｌ／ｈ（１４１０ｋＷ），製氷サイクルに循環する水の定格流量は４８３ｍ^３／ｈ，解氷サイクルに循環する水の定格流量は５８０ｍ^３／ｈである。蓄熱槽には，運転前に氷充填率ＩＰＦ＝４０％の氷が蓄えられている。以上のような氷蓄熱システムにおいて，運転中，常に１．５℃以下の低温の水を得るように制御した。
【００４６】
その結果，図５中の一点鎖線７１（横軸が時間，右側の縦軸が流量で表される）で示すように，１３時〜１６時の間は冷凍機と冷凍機に送液するポンプの稼働を停止し，製氷サイクルに循環する水とブラインの流量を０ｍ^３／ｈとすることができ，製氷サイクルの運転を停止できた。なお，図５中の実線７２（横軸が時間，右側の縦軸が流量で表される）で示すように，氷蓄熱システムの運転中は，解氷サイクルは運転を続けており，４時１５分〜６時の間を除いて解氷サイクルには常に水が循環している。氷蓄熱システムの運転中，１３時〜１６時以外の間は，製氷サイクルの運転と解氷サイクルが運転が両方とも行われる。図５中には，加えて，予熱器２３での交換熱量の経時的変化を一点鎖線７３（横軸が時間，左側の縦軸が単位時間あたりの冷却負荷で表される）で示し，冷却器５３での交換熱量の経時的変化を点線７４（横軸が時間，左側の縦軸が単位時間あたりの冷却負荷で表される）で示した。
【００４７】
図６は冷水温度と残蓄熱率の関係を示すグラフである。図６中の一点鎖線８０（横軸が時間，左側の縦軸が温度で表される）で示すように，氷蓄熱システムの運転中，常に１．５℃以下の低温の水を蓄熱槽から取水できることが演算された。なお図６中には，加えて，過冷却器に供給される水の温度の経時的変化を実線８１（横軸が時間，左側の縦軸が温度で表される）で示し，解氷サイクルから蓄熱槽へ戻される水の温度の経時的変化を実線８２（横軸が時間，左側の縦軸が温度で表される）で示し，残蓄熱率（残蓄熱量／運転前の蓄熱量）の経時的変化を実線８３（横軸が時間，左側の縦軸が残蓄熱率）で示した。なお，運転を停止できる最大時間は上述のように求めるが，その最大時間を割り振る時刻は，最も電力料金が高価な時間帯とする。この例では真昼であり，その製氷サイクルの運転停止中（１３時〜１６時）も残蓄熱量を演算した。但し，氷蓄熱システムの運転を行わない４時１５分〜６時の間は残蓄熱量の演算はせず，製氷もしていない。残蓄熱比（残蓄熱量／運転前の蓄熱量）を０．４以上に維持することで，１．５℃以下の低温の冷水が常に得られた。また，運転終了時には運転前の蓄熱量に戻すことができ，翌日の運転が可能になった。
【００４８】
【発明の効果】
本発明によれば，製氷サイクルの運転時間を短縮しつつ，冷却負荷の運転終了まで，水の温度を所定の上限温度に達しない範囲に制御でき，冷却負荷に対して所定の温度以下に冷却した熱媒を運転終了まで供給することが可能となる。そして，製氷サイクルの運転時間を短縮することにより，製氷コストをなるべく少なく抑えることが可能となる。
【図面の簡単な説明】
【図１】本発明の実施の形態にかかるダイナミック型氷蓄熱システムの概略的な構成を示す説明図である。
【図２】本発明の実施の形態にかかるダイナミック型氷蓄熱システムにおける，制御装置の演算工程を示すフローチャートである。
【図３】最大時間Ｘを求める演算工程を示すフローチャートである。
【図４】最大時間Ｘを求める別の計算モデルの説明図である。
【図５】本発明の実施例における，冷却負荷の時間的変化と製氷サイクルの運転の制御を示すグラフである。
【図６】本発明の実施例における，蓄熱槽から取水される水の温度の時間的変化と残蓄熱率の時間的変化を示すグラフである。
【符号の説明】
１氷蓄熱システム
１０蓄熱槽
１１水
１２氷
１３，２６，４７，４８，５６温度センサー
２０製氷サイクル
２１製氷取水管
２２，４１，５２ポンプ
２３予熱器
２４過冷却器
２５，４６，５５流量センサー
３０製造プロセス
３１，３２熱媒循環回路
３５往ヘッダ
３６還ヘッダ
４０冷凍機
４２ブライン往管
４３ブライン還管
４５過冷却解除パイプ
５０解氷サイクル
５１解氷取水管
５３冷却器
６０制御装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dynamic ice storage tank system and an operation method thereof.
[0002]
[Prior art]
An ice heat storage system in which cold heat is stored in a smaller heat storage tank by utilizing the melting latent heat of ice has become widespread. The ice-making type ice heat storage system is a static type ice heat storage system in which block-shaped ice is produced around the heat transfer tubes in the heat storage tank, and the ice making process, ice storage process, and ice melting process are performed in the same heat storage tank. , There is a dynamic ice heat storage system that supplies ice / water slurry produced by an ice maker outside the heat storage tank to the heat storage tank. The static type ice heat storage system is used as a heat source device for building air conditioning systems and cooling of the manufacturing process in the factory. It is adopted by. On the other hand, dynamic ice heat storage systems have recently been adopted as heat source equipment for building air conditioning systems.
[0003]
Generally, in cooling of a manufacturing process, it is necessary to continuously supply low-temperature cold water (for example, 24 hours operation) as compared with a building air conditioning system. Especially in the manufacturing process of food, pharmaceuticals, semiconductors and other electronic parts, even when sharp and large cooling load (peak cooling load) occurs, always supply low-temperature cold water close to 0 ° C. It is required to do. When low-temperature cold water is continuously supplied day and night in this way, an ice-melting process for raising the temperature of the water in the heat storage tank and an ice-making process for cooling the water in the heat storage tank are performed simultaneously.
[0004]
Here, in the static ice heat storage system, when the ice melting process and the ice making process are performed at the same time, in the static ice heat storage system, ice growth and melting are performed around a limited heat transfer tube. The ability to cool the heat source water (water) in the heat storage tank is limited to the surface area of the heat transfer tube or the surface area of ice. For this reason, in a static type ice heat storage system, it becomes difficult to continuously obtain cold water having a low temperature close to 0 ° C. for a sharp and large heat load.
[0005]
[Problems to be solved by the invention]
On the other hand, in a dynamic type ice heat storage system, sherbet-like ice is stored in a heat storage tank supplied with ice / water slurry manufactured outside the heat storage tank, so the ice making process and the ice melting process are separated. In general dynamic ice storage systems for air conditioning applications, ice making and de-icing processes are usually not performed at the same time. However, if these processes are performed simultaneously in a dynamic ice storage system, a heat storage tank is used. Regardless of the melting of ice inside, ice / water slurry can be supplied to the heat storage tank, and cold water close to 0 ° C. can be continuously obtained even for a sharper and larger heat load. However, in the dynamic ice heat storage system, when the ice making process and the ice melting process are performed at the same time, it is difficult to avoid the ice making process during the day when energy costs such as electric power are high.
[0006]
Therefore, an object of the present invention is to provide a dynamic ice heat storage system capable of continuously obtaining low-temperature cold water near 0 ° C. even when a sharp and large heat load is generated while keeping ice making costs as low as possible. It is to provide a driving method.
[0007]
[Means for Solving the Problems]
In order to achieve this object, according to the present invention, a heat storage tank for storing ice, an ice making cycle for cooling water taken from the heat storage tank to supply ice / water slurry to the heat storage tank, and water intake from the heat storage tank The ice-melting cycle returns the heated water to the heat storage tank and a controller that controls the intake of water from the heat storage tank to the ice making cycle. The ice / water slurry produced in the ice making cycle is stored in the heat storage tank. It is a dynamic ice heat storage system that supplies and stores heat and cools the cooling load of the manufacturing process in the ice-breaking cycle, and the control device floats in the heat storage tank with the time variation of the cooling load of the manufacturing process set in advance. Calculate the temperature of water taken from the heat storage tank until the end of the cooling load operation of the manufacturing process, The maximum time X during which the operation of the ice making cycle can be stopped is determined within a range in which the calculated water temperature does not reach the predetermined upper limit temperature until the operation of the cooling load of the manufacturing process is completed. Control to stop operation A dynamic ice heat storage system is provided.
[0008]
According to the present invention, the heat storage tank for storing ice, the ice making cycle for cooling the water taken from the heat storage tank and supplying it to the heat storage tank as ice / water slurry, and heat exchange between the water taken from the heat storage tank, And an ice-free cycle that returns the heated water to the heat storage tank. The ice / water slurry produced in the ice-making cycle is supplied to the heat storage tank to store heat, Manufacturing process A method for operating a dynamic ice storage system for cooling a cooling load, which is set in advance. Manufacturing process Change in cooling load over time And the heat of fusion of ice floating in the heat storage tank The temperature of the water taken from the heat storage tank Manufacturing process Calculate until the cooling load is finished, and the calculated water temperature is Manufacturing process A step of obtaining a maximum time X during which the operation of the ice making cycle can be stopped within a range in which the predetermined upper limit temperature is not reached until the operation of the cooling load is completed, and a step of stopping the operation of the ice making cycle during the maximum time X , Supplying the water taken from the heat storage tank to the heat storage tank as ice / water slurry in the ice making cycle, and returning the heated water to the heat storage tank by exchanging heat in the ice melting cycle. Provided is a method for operating a dynamic ice heat storage system, characterized in that the ice process is performed in a timely manner.
[0009]
In this operation method, when the maximum time X does not exceed a predetermined lower limit stop time (for example, the time of the refrigerator restart prevention timer), the operation of the ice making cycle may not be stopped. .
[0010]
According to the invention, it varies Manufacturing process The supply of cold heat does not fall below the demand for cooling load, shortening the operation time of the ice making cycle, Manufacturing process Until the cooling load operation ends, the temperature of the water can be controlled within the range not reaching the predetermined upper limit temperature, Manufacturing process It becomes possible to supply the heat medium cooled to a predetermined temperature or less with respect to the cooling load until the end of operation.
According to the present invention, the heat storage tank for storing ice, the ice making cycle for cooling the water taken from the heat storage tank and supplying it to the heat storage tank as ice / water slurry, and heat exchange between the water taken from the heat storage tank, And an ice-free cycle that returns the heated water to the heat storage tank. The ice / water slurry produced in the ice-making cycle is supplied to the heat storage tank to store heat, Manufacturing process When operating a dynamic ice storage system that cools the cooling load, Manufacturing process Change in cooling load over time And the heat of fusion of ice floating in the heat storage tank The temperature of the water taken from the heat storage tank Manufacturing process Calculate until the cooling load is finished, and the calculated water temperature is Manufacturing process Provided is a method for predicting the maximum time X in a dynamic ice heat storage system, characterized in that the maximum time X during which the operation of the ice making cycle can be stopped within a range where the predetermined upper limit temperature is not reached until the cooling load operation is completed is provided. The
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, in a dynamic ice heat storage system 1 (hereinafter referred to as “ice heat storage system 1”) according to an embodiment of the present invention, water 11 is filled in a heat storage tank 10. In addition, sherbet-like ice 12 generated by an ice making cycle 20 described below is stored in water 11 in the heat storage tank 10. A temperature sensor 13 is attached to the bottom of the heat storage tank 10, and the temperature T <b> 1 of the water 11 in the heat storage tank 10 is detected by the temperature sensor 13.
[0012]
The ice making cycle 20 takes water from the heat storage tank 10 by operating an ice making water intake pipe 21 that takes water from the lower part of the heat storage tank 10 (bottom or below the range where no ice is present) and a pump 22 provided in the ice making water intake pipe 21. A preheater 23 that preheats the water 11 and a supercooler 24 for ice making that cools the water 11 to a temperature below the freezing point after preheating by the preheater 23 are provided. A flow sensor 25 and a temperature sensor 26 are attached to the ice making water pipe 21, and the flow rate F 1 of the water 11 fed by the ice making water pipe 21 is detected by the flow sensor 25, and passes through the preheater 23 and the supercooler. The temperature T2 of the water 11 fed to 24 is detected by the temperature sensor 26.
[0013]
The preheater 23 is provided with a heat medium circulation circuit 31 that circulates heat medium water with the manufacturing process 30 as an example of a cooling load. In the preheater 23, the heat medium water circulated and supplied to the manufacturing process 30 through the heat medium circulation circuit 31 and the water 11 fed through the ice making water pipe 21 perform heat exchange, and the heat medium water is cooled. The water 11 is heated. As a result, the heat transfer water cooled by the preheater 23 is circulated and supplied to the manufacturing process 30, and the water 11 heated by the preheater 23 is supplied to the subcooler 24.
[0014]
Brine (antifreeze) cooled by the refrigerator 40 is circulated and supplied to the supercooler 24 through the brine forward pipe 42 and the brine return pipe 43 by the operation of the pump 41. The refrigerator 40 includes a refrigerator condenser, a cooling tower, and the like for cooling the brine to a sub-freezing temperature.
[0015]
In the supercooler 24, the water 11 supplied through the ice making water intake pipe 21 is cooled to a supercooled state of −2 to −3 ° C. by the cold heat of the brine. The water 11 thus cooled to the supercooled state is discharged from the supercooler 24, and changes in phase from the water state to the ice state in the supercooling release pipe 45 to become ice / water slurry in the heat storage tank 10. It comes to be supplied. Thereby, the sherbet-like ice 12 is stored in the water 11 inside the heat storage tank 10.
[0016]
A flow rate sensor 46 and a temperature sensor 47 are mounted on a brine forward pipe 42 that sends brine from the refrigerator 40 to the supercooler 24, and the flow rate F 2 of the brine fed to the brine forward pipe 42 is a flow rate sensor. The temperature T3 of the brine detected by 46 and fed to the subcooler 24 is detected by the temperature sensor 47. A temperature sensor 48 is attached to the brine return pipe 43, and the temperature T 4 of the brine returned to the refrigerator 40 through the brine return pipe 43 is detected by the temperature sensor 48.
[0017]
The de-icing cycle 50 includes a de-icing water intake pipe 51 that takes cold water from below the heat storage tank 10, and a pump 52 that is provided in the de-icing water intake pipe 51, takes water 11 from the heat storage tank 10, and supplies cold heat to the load. And the cooler 53 which heat-exchanges the heat-medium water of the manufacturing process 30 with the water 11 is provided. In addition, the system which supplies intake water directly to the manufacturing process 30 may be used. In this case, the heat exchanger that directly exchanges heat between the water 11 and the beverage, for example, corresponds to the cooler 53. A flow sensor 55 and a temperature sensor 56 are attached to the deicing water intake pipe 51, and the flow rate F3 of the water 11 fed by the deicing water intake pipe 51 is detected by the flow sensor 55, and the temperature T5 of the water 11 is the temperature. It is detected by the sensor 56.
[0018]
A heat medium circulation circuit 32 that circulates the heat medium water with the manufacturing process 30 is introduced into the cooler 53. In the cooler 53, the heat medium water circulated and supplied to the manufacturing process 30 through the heat medium circulation circuit 32 and the water 11 fed through the deicing water intake pipe 51 perform heat exchange, and the heat medium water is cooled. The water 11 is heated. Accordingly, the heat transfer water cooled by the cooler 53 is circulated and supplied to the manufacturing process 30, and the water 11 heated by the cooler 53 is returned again to the upper side of the heat storage tank 10 from the deicing water intake pipe 51. . The heated water 11 defrosts the ice 12 in the tank.
[0019]
The manufacturing process 30 includes a forward header 35 and a return header 36. As described above, the heat medium water supplied from the preheater 23 via the heat medium circuit 31 and the heat medium water supplied from the cooler 53 via the heat medium circuit 32 are merged in the forward header 35, The supply pipe 37 appropriately supplies a desired place in the manufacturing process 30. On the other hand, the heat medium water returned from each part of the manufacturing process 30 through the return pipe 38 is joined by the return header 36 and then passed through the heat medium circulation circuit 31 and the heat medium circulation circuit 32 described above. 23 and cooler 53 are distributed back.
[0020]
The manufacturing process 30 requires cooling of, for example, beverages and chemical raw materials, and the manufacturing process 30 is always required to supply low-temperature cold water close to 0 ° C. The temporal change of the cooling load required in the manufacturing process 30 is set in advance and is input to the control device 60 provided in the ice heat storage system 1. Further, the temperature T1 of the water 11 detected by the temperature sensor 13 described above, the temperature T2 of the water 11 detected by the temperature sensor 26, the temperature T3 of the brine detected by the temperature sensor 47, and the temperature sensor 48. Detected by the flow rate F2 of the water 11 detected by the flow rate sensor 46, the flow rate F1 of the water 11 detected by the flow rate sensor 46, the flow rate F1 of the water 11 detected by the flow rate sensor 25. The flow rate F <b> 3 of the water 11 is input to the control device 60. As will be described later, the control device 60 performs an operation based on the temporal change of the cooling load thus input and the temperatures T1, T2, T3, T4, T5, flow rates F1, F2, and F3, and the ice making cycle. 20, the operation of the pump 22, the refrigerator 40 and the pump 41 provided in the ice making water intake pipe 21 is controlled. In addition, the temperature of the water taken in is the same temperature on the preheater side and the cooler side, and the temperature sensor may be one of reference numerals 26 and 47.
[0021]
Now, in the ice heat storage system 1 configured as described above, in the ice making cycle 20, the water 11 taken from the lower part of the heat storage tank 10 by the operation of the pump 22 passes through the ice making water intake pipe 21, and the preheater. 23 and the supercooler 24 are fed in this order. In the preheater 23, the water 11 is heated to a temperature exceeding the freezing point (for example, about 0.5 ° C.) by performing heat exchange with the heat medium water sent through the heat medium circulation circuit 31, and is supercooled. The liquid is fed to the vessel 24 (note that the water is not heated when the water intake temperature is about 0.5 ° C. or higher, for example). In the supercooler 24, the water 11 thus supplied is stabilized in a supercooled state of −2 to −3 ° C. by the cold heat of the brine circulated from the refrigerator 40 through the brine forward pipe 42 and the brine return pipe 43. And let it cool. The water 11 thus cooled to the supercooled state is discharged from the supercooler 24, and changes in phase from the water state to the ice state in the supercooling release pipe 45 to become ice / water slurry in the heat storage tank 10. Supply. Thus, the inside of the heat storage tank 10 is in a state in which the water 11 is filled with the sherbet-like ice 12. Further, the heat medium water cooled by exchanging heat with the water 11 in the preheater 23 is circulated and supplied to the manufacturing process 30 through the heat medium circulation circuit 31.
[0022]
On the other hand, in the deicing cycle 50, the water 11 taken from the bottom of the heat storage tank 10 is sent to the cooler 53 through the deicing water intake pipe 51 by the operation of the pump 52. In the cooler 53, the water 11 is heated by exchanging heat with the heat medium water sent through the heat medium circulation circuit 32, and thus the water 11 is heated up, and the water 11 is discharged from the deicer intake pipe 51. It returns again above the heat storage tank 10. Further, the heat transfer water cooled by exchanging heat with the water 11 in the cooler 53 is circulated and supplied to the manufacturing process 30 via the heat transfer circuit 32.
[0023]
Thus, the heat transfer water cooled by the preheater 23 and the cooler 53 is supplied to the manufacturing process 30, and low temperature cold water close to 0 ° C. can always be supplied to the manufacturing process 30. It becomes possible.
[0024]
Here, in the ice heat storage system 1 configured as described above, the temporal change of the cooling load required in the manufacturing process 30 is set in advance, and the temporal change of the cooling load is determined by the control device 60. Has been entered. As shown in FIG. 2, when the ice heat storage system 1 is first activated (S1), the control device 60 causes the temperature T1 of the water 11 detected by the temperature sensor 13 and the temperature 11 detected by the temperature sensor 26. The temperature T2, the brine temperature T3 detected by the temperature sensor 47, the brine temperature T4 detected by the temperature sensor 48, the temperature T5 of the water 11 detected by the temperature sensor 56, and the water 11 detected by the flow sensor 25. The flow rate F1, the brine flow rate F2 detected by the flow rate sensor 46, and the flow rate F3 of the water 11 detected by the flow rate sensor 55 are input (S2).
[0025]
Next, the control device 60 performs a calculation based on the temperatures T1, T2, T3, T4, T5 and the flow rates F1, F2, F3 input in this way, and first, the remaining heat storage amount (cooling heat) remaining in the heat storage tank 10 Amount) is obtained (S3). Here, the temporal change in the remaining heat storage amount (cold heat amount) remaining in the heat storage tank 10 includes the supply amount of the cold energy to the heat storage tank 10 per unit time and the extraction of the cold heat from the heat storage tank 10 per unit time. It can be expressed as the difference between the amount (equal to “the amount of cold energy per unit time supplied to the heat transfer medium of the production process 30”). Then, by integrating (integrating) the temporal changes represented in this way over time, the remaining heat storage amount (cold heat amount) remaining in the heat storage tank 10 is obtained.
[0026]
In determining the amount of remaining stored heat (cold heat) remaining in the heat storage tank 10, the amount of cold energy supplied to the heat storage tank 10 per unit time is supplied from the refrigerator 40 to the subcooler 24 via the brine forward pipe 42. The temperature difference T3-T4 between the temperature T3 of the supplied brine and the temperature T4 of the brine returned from the supercooler 24 through the brine return pipe 43 to the refrigerator 40, and the brine forward pipe 42 and the brine return pipe 43 are fed. The specific heat and specific gravity of the brine can be taken into consideration based on the brine flow rate F2. The amount of cold energy taken out from the heat storage tank 10 per unit time is the sum of the amount of cold energy per unit time taken out from the water 11 by the preheater 23 and the amount of cold heat per unit time taken out from the water 11 by the cooler 53. is there. The amount of cold per unit time taken out from the water 11 by the preheater 23 is the difference T1-T2 between the temperature T1 of the water 11 in the heat storage tank 10 and the temperature T2 of the water 11 fed to the subcooler 24, and ice making. Based on the flow rate F1 of the water 11 fed through the intake pipe 21, the specific heat and specific gravity of the water 11 can be taken into consideration. The amount of cold energy per unit time taken out from the water 11 by the cooler 53 is the difference T1-T5 between the temperature T1 of the water 11 in the heat storage tank 10 and the temperature T5 of the water 11 returned from the cooler 53 to the heat storage tank 10. Based on the flow rate F3 of the water 11 fed through the de-icing water intake pipe 51, the specific heat and specific gravity of the water 11 can be taken into consideration.
[0027]
After determining the remaining stored heat amount (cold heat amount) remaining in the heat storage tank 10 in this manner, the control device 60 then performs a time-dependent change in the cooling load required in the manufacturing process 30 set in advance as described above. Thus, the temperature T1 of water taken from the heat storage tank 10 (equal to the temperature T1 of the water 11 in the heat storage tank 10) is calculated until the operation of the manufacturing process 30 as a cooling load is completed. In this way, the maximum time X during which the operation of the ice making cycle 20 can be stopped is determined in a range where the calculated temperature T1 of the water 11 does not reach the predetermined upper limit temperature until the operation of the manufacturing process 30 as a cooling load is completed (S4).
[0028]
Here, the maximum time X is obtained as follows. That is, as shown in FIG. 3, it is first assumed that the maximum time X = 0 (S10). Note that the maximum time X = 0 means a state in which the ice making cycle 20 is continuously operated until the operation of the manufacturing process 30 is completed without stopping the operation of the ice making cycle 20. First, the maximum time X = 0 Assuming The temperature T1 of water taken from the heat storage tank 10 is calculated until the operation of the manufacturing process 30 is finished (S11).
[0029]
Here, the temporal change dT1 / dt of the temperature T1 of water taken from the heat storage tank 10 can be expressed by the following equation (1).
C · ρ · η · V ′ (dT1 / dt) = Q1−Q2 (1)
[0030]
In this formula (1), Q1 is a temporal change in the cooling load set in the control device 60 in advance. Q <b> 2 is the amount of heat of fusion of the ice 12 floating in the heat storage tank 10. C is the specific heat of water. ρ is the specific gravity of water. V ′ indicates the volume of the region of the water 11 other than the sherbet-shaped ice 12 in the heat storage tank 10, and V ′ = V · η. V is the volume of the heat storage tank 10. η indicates a utilization rate of heat storage, and η = 1− (residual heat storage amount / maximum heat storage amount). In addition, Q2 can be calculated | required from another experiment rearrangement formula (a function, such as a dimension of a thermal storage tank, operating conditions (T5, F3), (eta)).
[0031]
Then, by integrating (integrating) the temporal change (dT1 / dt) expressed as described above, the temperature T1 of the water 11 taken from the heat storage tank 10 is calculated until the operation of the manufacturing process 30 is completed. To do.
[0032]
Actually, ice / water slurry is supplied into the heat storage tank 10 from the supercooling release pipe 45, and the ice 12 is floating in the heat storage tank 10 as schematically shown in FIG. There is a bypass portion 66 in which the portion of the ice layer 65 and the water 11 falling from the supercooling release pipe 45 does not contact the ice 12 in the heat storage tank 10 and flows to the lower part of the heat storage tank 10. In the calculation model shown in FIG. 4, the temporal change dT1 / dt of the temperature T1 of water taken from the heat storage tank 10 can be expressed by the following equation (2).
C · ρ · V ′ · (dT1 / dt) = C · ρ · F3 · Tb + C · ρ · Fbw · Tbw−C · ρ · (F3 + Fbw) · T1 (2)
[0033]
In this equation (2), Tb is the boundary temperature between the water area and the ice layer 65 formed at the bottom of the heat storage tank 10 by melting the ice layer 65. Fbw is the flow rate of the water 11 flowing through the bypass portion 66. Tbw is the temperature of the water 11 dropped from the supercooling release pipe 45 (equal to the temperature of the water 11 flowing through the bypass portion 66). Tb can be obtained from the relationship with Q2 in the following equation (3).
Q2 = C · ρ · F3 · (Tb−T5) (3)
[0034]
In the calculation model shown in FIG. 4, the temperature change T1 of the water 11 taken from the heat storage tank 10 is obtained by integrating (integrating) the temporal change (dT1 / dt) expressed in this way with time. It is possible to calculate until the end of 30 operations.
[0035]
After calculating the temperature T1 of the water 11 taken from the heat storage tank 10 until the end of the operation of the manufacturing process 30, the temperature T1 of the water 11 is until the end of the operation of the manufacturing process 30 as shown in FIG. In step S12, it is determined whether the temperature is lower than a predetermined upper limit temperature. Here, the predetermined upper limit temperature is determined according to the demand of the manufacturing process 30, and is set to about 1.5 ° C., for example, in the manufacturing process for cooling the beverage.
[0036]
If the temperature T1 of the water 11 is always below the predetermined upper limit temperature until the end of the operation of the manufacturing process 30 in the determination of S12, the maximum time X = X + ΔX is set (S13). Next, for the maximum time X increased by ΔX as described above, the temperature T1 of water taken from the heat storage tank 10 is calculated again until the end of the operation of the manufacturing process 30 (S11). Thereafter, it is determined whether or not the temperature T1 of the water 11 is lower than a predetermined upper limit temperature until the end of the operation of the manufacturing process 30 (S12). Thus, as long as the temperature T1 of the water 11 is always lower than the predetermined upper limit temperature until the end of the operation of the manufacturing process 30, the maximum time X is continuously increased by ΔX.
[0037]
On the other hand, if it is determined in S12 that the temperature T1 of the water 11 is equal to or higher than the predetermined upper limit temperature until the end of the operation of the manufacturing process 30, the maximum time X is determined (S14). In this case, the maximum time X is a time immediately before the temperature T1 of the water 11 becomes equal to or higher than a predetermined upper limit temperature. In this way, the maximum time X is obtained.
[0038]
Next, as shown in FIG. 2, it is determined whether or not the maximum time X thus obtained exceeds a predetermined lower limit stop time (S5). Here, the predetermined lower limit stop time is determined by the refrigerator 40, for example, a value of a restart prevention timer of the refrigerator 40.
[0039]
If it is determined in S5 that the maximum time X exceeds the predetermined lower limit stop time, the operation of the ice making cycle 20 is stopped (S6). In this case, the operation of the ice making cycle 20 is stopped by stopping the operation of the pump 22, the refrigerator 40 and the pump 41 provided in the ice making water intake pipe 21. If the refrigerator 40 does not have the lower limit stop time as described above, the determination shown in S5 is omitted, and the operation of the ice making cycle 20 is immediately stopped except when the maximum time X is zero. good.
[0040]
After stopping the operation of the ice making cycle 20 in this manner, the control device 60 performs the calculation again based on the temperatures T1, T2, T3, T4, T5 and the flow rates F1, F2, F3 at that time, as before. It carries out and calculates | requires the remaining heat storage amount (cold heat amount) remaining in the thermal storage tank 10 (S3). Thereafter, the control device 60 determines the temperature T1 of the water taken from the heat storage tank 10 (the temperature T1 of the water 11 in the heat storage tank 10) based on the temporal change of the cooling load required in the preset manufacturing process 30. Is calculated again until the operation of the manufacturing process 30 as the cooling load is completed, and the ice making cycle 20 is within a range in which the temperature T1 of the water 1 does not reach the predetermined upper limit temperature until the operation of the manufacturing process 30 as the cooling load is completed. The maximum time X during which the operation can be stopped is determined according to the process described above with reference to FIG. 3 (S4). Then, it is determined whether or not the maximum time X exceeds a predetermined lower limit stop time (S5). Thus, the operation of the ice making cycle 20 is stopped until the maximum time X does not exceed the predetermined lower limit stop time. When the refrigerator 40 does not have the lower limit stop time as described above, the operation of the ice making cycle 20 is stopped until the maximum time X becomes zero.
[0041]
On the other hand, if the maximum time X does not exceed the predetermined lower limit stop time in the determination of S5, the operation of the ice making cycle 20 is not stopped. In the case where the refrigerator 40 does not have the lower limit stop time as described above, the operation of the ice making cycle 20 is not stopped when the maximum time X is 0 (note that the refrigerator 40 has the above-described operation). If there is no maximum load when there is no maximum load, such as when operating a separate lower limit stop time, for example, by operating a refrigerator provided separately or by cooling the cold system, if the maximum time X is 0, the ice making cycle 20 Do not stop driving).
[0042]
Even when the operation of the ice making cycle 20 is not stopped in this way, the control device 60 always calculates again based on the temperatures T1, T2, T3, T4, T5 and the flow rates F1, F2, F3 at that time, as before. The remaining heat storage amount (cold heat amount) remaining in the heat storage tank 10 is obtained (S3). Similarly, the temperature T1 of the water 1 reaches a predetermined upper limit temperature until the operation of the manufacturing process 30 as a cooling load is completed. The maximum time X during which the operation of the ice making cycle 20 can be stopped is determined within a range not to be used (S4). In this way, it is determined whether or not the maximum time X exceeds the predetermined lower limit stop time (S5), or whether or not the maximum time X has become 0, and the operation of the ice making cycle 20 is controlled.
[0043]
Thus, the ice heat storage system 1 described with reference to FIG. 1 is a range in which the temperature T1 of the water 1 does not reach the predetermined upper limit temperature until the operation of the manufacturing process 30 as a cooling load is completed while shortening the operation time of the ice making cycle 20. Can be controlled. As a result, the heat transfer water cooled to a predetermined temperature or lower can be supplied to the manufacturing process 30 until the end of operation. Because necessary and sufficient ice making is done, it is energy saving.
[0044]
As mentioned above, although an example of preferable embodiment of this invention was demonstrated, this invention is not limited to the form demonstrated here. For example, the manufacturing process 30 for food or the like is shown and described as an example of the cooling load. However, in the present invention, the cooling load is not limited to such a manufacturing process. For example, air conditioning (such as cooling of a building) or other heat source is used. The present invention may be applied to a cooling load other than the manufacturing process such as a refrigerator (cooling, cooling of a showcase, cooling of a cable tunnel).
[0045]
【Example】
Examples of the present invention will be described below. In the ice heat storage system described with reference to FIG. 1, a simulation was performed for operation according to the present invention. A solid line 70 in FIG. 5 shows a change in the cooling load in one day, with the horizontal axis representing time and the left vertical axis representing cooling load per unit time. It was assumed that the operation time of the manufacturing process was from 0 o'clock to past 22:00, the manufacturing process was not operated after 22:15 and 24:00, and the cooling load changed during operation as indicated by the solid line 70. In addition, it was assumed that the cooling load of the manufacturing process does not occur continuously, and there is a sharp load of about 30 minutes in one hour and no load for the remaining 30 minutes. The size of the heat storage tank is 11 x 14 x 2.27 mH (capacity 350 m ³ ), The capacity of the ice making cycle (ice making capacity) is 1210 Mcal / h (1410 kW), and the rated flow rate of water circulating in the ice making cycle is 483 m ³ / H, the rated flow rate of water circulating in the de-icing cycle is 580m ³ / H. In the heat storage tank, ice having an ice filling rate IPF = 40% is stored before operation. The ice heat storage system as described above was controlled so as to always obtain low-temperature water of 1.5 ° C or lower during operation.
[0046]
As a result, as indicated by a one-dot chain line 71 in FIG. 5 (the horizontal axis represents time and the right vertical axis represents the flow rate), the operation of the pump that feeds the refrigerator and the refrigerator between 13:00 and 16:00 And the flow rate of water and brine circulating in the ice making cycle is 0m. ³ / H, and the operation of the ice making cycle could be stopped. As indicated by the solid line 72 in FIG. 5 (the horizontal axis is time and the right vertical axis is the flow rate), the ice-melting cycle continues to operate during the operation of the ice heat storage system. Water is constantly circulating in the de-icing cycle except between 15 minutes and 6 hours. During the operation of the ice heat storage system, during the time other than 13:00 to 16:00, both the operation of the ice making cycle and the operation of the ice melting cycle are performed. In FIG. 5, in addition, the change over time in the amount of exchange heat in the preheater 23 is indicated by a one-dot chain line 73 (the horizontal axis is represented by time, and the left vertical axis is represented by the cooling load per unit time). The change with time in the amount of exchange heat in the vessel 53 is indicated by a dotted line 74 (the horizontal axis is time, and the left vertical axis is the cooling load per unit time).
[0047]
FIG. 6 is a graph showing the relationship between the cold water temperature and the remaining heat storage rate. As shown by the alternate long and short dash line 80 in FIG. 6 (the horizontal axis represents time, and the left vertical axis represents temperature), during operation of the ice heat storage system, low temperature water of 1.5 ° C. or less is always supplied from the heat storage tank. It was calculated that water could be taken. In addition, in FIG. 6, the change over time in the temperature of the water supplied to the subcooler is shown by a solid line 81 (the horizontal axis is time and the left vertical axis is temperature), and the ice melting cycle The change over time in the temperature of the water returned to the heat storage tank is indicated by a solid line 82 (the horizontal axis is time, the left vertical axis is temperature), and the residual heat rate (residual heat amount / heat storage amount before operation) The change over time is shown by a solid line 83 (the horizontal axis is time, and the left vertical axis is the remaining heat storage rate). The maximum time during which the operation can be stopped is obtained as described above, but the time at which the maximum time is allocated is a time zone in which the power charge is most expensive. In this example, it was midday, and the remaining heat storage amount was calculated even when the operation of the ice making cycle was stopped (13:00 to 16:00). However, during the period from 4:15 to 6:00 when the ice heat storage system is not operated, the remaining heat storage amount is not calculated and ice is not made. By maintaining the residual heat storage ratio (residual heat storage / heat storage before operation) at 0.4 or higher, low-temperature cold water of 1.5 ° C. or lower was always obtained. At the end of the operation, the amount of heat stored before the operation was restored, and the next day's operation became possible.
[0048]
【Effect of the invention】
According to the present invention, it is possible to control the temperature of water so that it does not reach the predetermined upper limit temperature until the cooling load operation ends, while shortening the operation time of the ice making cycle, and cooling the cooling load to a predetermined temperature or less. It becomes possible to supply the heated heat medium until the end of operation. By reducing the operation time of the ice making cycle, it is possible to keep the ice making cost as low as possible.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a dynamic ice heat storage system according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a calculation process of a control device in the dynamic ice storage system according to the embodiment of the present invention.
FIG. 3 is a flowchart showing a calculation process for obtaining a maximum time X;
FIG. 4 is an explanatory diagram of another calculation model for obtaining the maximum time X;
FIG. 5 is a graph showing the temporal change of the cooling load and the control of the operation of the ice making cycle in the example of the present invention.
FIG. 6 is a graph showing a temporal change in the temperature of water taken from the heat storage tank and a temporal change in the residual heat storage rate in the embodiment of the present invention.
[Explanation of symbols]
1 Ice heat storage system
10 Thermal storage tank
11 Water
12 Ice
13, 26, 47, 48, 56 Temperature sensor
20 ice making cycle
21 Ice making pipe
22, 41, 52 Pump
23 Preheater
24 Supercooler
25, 46, 55 Flow sensor
30 Manufacturing process
31, 32 Heat medium circulation circuit
35 Forward header
36 Return header
40 refrigerator
42 Brine Outlet
43 Brine return pipe
45 Supercooling release pipe
50 de-icing cycle
51 De-icing water intake pipe
53 Cooler
60 Control device

Claims

A heat storage tank that stores ice, an ice-making cycle that cools the water taken from the heat storage tank and supplies it to the heat storage tank as ice / water slurry, and heat-exchanges the water taken from the heat storage tank, and heats the heated water to the heat storage tank And a control device that controls water intake from the heat storage tank to the ice making cycle.
A dynamic ice heat storage system that supplies ice and water slurry produced in an ice making cycle to a heat storage tank to store heat and cools the cooling load of the production process in an ice melting cycle.
The control device determines the temperature of the water taken from the heat storage tank based on the time-dependent change in the cooling load of the manufacturing process and the amount of melting heat of ice floating in the heat storage tank. The maximum time X during which the operation of the ice making cycle can be stopped is calculated within the range where the calculated water temperature does not reach the predetermined upper limit temperature until the end of the cooling load operation of the manufacturing process. A dynamic ice heat storage system that controls the ice making cycle to stop during X.

A heat storage tank that stores ice, an ice-making cycle that cools the water taken from the heat storage tank and supplies it to the heat storage tank as ice / water slurry, and heat-exchanges the water taken from the heat storage tank, and heats the heated water to the heat storage tank A de-icing cycle to return to
An operation method of a dynamic ice heat storage system in which ice / water slurry produced in an ice making cycle is supplied to a heat storage tank to store heat, and the cooling load of the manufacturing process is cooled in an ice melting cycle,
Calculates the temperature of water taken from the heat storage tank until the end of the cooling load operation of the manufacturing process based on the time-dependent change in the cooling load of the manufacturing process and the amount of melting heat of ice floating in the heat storage tank Determining a maximum time X during which the operation of the ice making cycle can be stopped within a range in which the calculated water temperature does not reach a predetermined upper limit temperature until the cooling load operation of the manufacturing process is completed;
During the maximum time X, the process of stopping the operation of the ice making cycle is included.
Supplying water taken from the heat storage tank to the heat storage tank as ice / water slurry in the ice-making cycle, and de-icing the water taken from the heat storage tank to the heat storage tank by exchanging heat in the ice-breaking cycle A method for operating a dynamic ice heat storage system, characterized in that the process is performed in a timely manner.

3. The operation method of the dynamic ice heat storage system according to claim 2, wherein the operation of the ice making cycle is not stopped when the maximum time X does not exceed a predetermined lower limit stop time.

A heat storage tank that stores ice, an ice-making cycle that cools the water taken from the heat storage tank and supplies it to the heat storage tank as ice / water slurry, and heat-exchanges the water taken from the heat storage tank, and heats the heated water to the heat storage tank A de-icing cycle to return to
When operating a dynamic ice heat storage system that supplies ice / water slurry produced in an ice making cycle to a heat storage tank to store heat, and cools the cooling load of the manufacturing process in an ice melting cycle.
Calculates the temperature of water taken from the heat storage tank until the end of the cooling load operation of the manufacturing process based on the time-dependent change in the cooling load of the manufacturing process and the amount of melting heat of ice floating in the heat storage tank And determining a maximum time X during which the operation of the ice making cycle can be stopped within a range in which the calculated water temperature does not reach a predetermined upper limit temperature until the cooling load operation of the manufacturing process is completed. Prediction method of maximum time X in an ice heat storage system.