JP3753762B2

JP3753762B2 - Waste heat recovery boiler

Info

Publication number: JP3753762B2
Application number: JP24338795A
Authority: JP
Inventors: 淳夫河原; 利則重中; 和弘武永
Original assignee: Babcock Hitachi KK
Current assignee: Mitsubishi Power Ltd
Priority date: 1995-09-21
Filing date: 1995-09-21
Publication date: 2006-03-08
Anticipated expiration: 2015-09-21
Also published as: JPH0988516A

Description

【０００１】
【発明の属する技術分野】
本発明は複合発電プラントにおいて、特に熱回収が効率的に行え、プラント性能の高効率化ができるように給水系統及び給水装置を配置した排熱回収ボイラに関する。
【０００２】
【従来の技術】
複合発電プラントにおいては、例えば図７の複合発電プラントの概略系統図に示すように、ガスタービン開放サイクル部と排熱回収ボイラと蒸気タービンサイクル部と発電機を備えて構成されている。図７の排熱回収ボイラは高圧、中圧、低圧からなる三重圧ボイラの例である。
【０００３】
ガスタービン開放サイクル部では、ガスタービン４で発電を行うと共に、ガスタービン４で仕事をした排ガスを排ガス通路６へ排出する。排出された高温の排ガスは排ガス通路６を経て排熱回収ボイラ５に導入され排ガス中の熱が回収される。また、蒸気タービンサイクル部では、排熱回収ボイラで発生した蒸気により蒸気タービン７でサイクル発電を行う。
【０００４】
このような複合発電プラントは、ガスタービン４と蒸気タービン７による複合発電を行うために発電効率が高いことと、ガスタービン４による発電が負荷応答性に優れていることから、急激な電力需要の変化に対する追従性が高いことなどの特徴がある。特に最近の高頻度の起動停止(ＤａｉｌｙＳｔａｒｔＳｔｏｐ、以下、ＤＳＳとする)を行う運転には有効である。
【０００５】
複合発電プラントにおける排熱回収ボイラの蒸気タービンへの蒸気供給系(以下、蒸気系とする)について図７で説明する。図７では排熱回収ボイラ５内に構成されている給水に係る装置（以下、給水系とする）の記載をドラムを除き省略している。
【０００６】
ガスタービン４では、空気供給管１からの燃焼用空気と燃料供給管２からの燃料とが燃焼器において混合され、燃焼されることによって生じた燃焼ガスでガスタービン４を回転し、発電機によって発電が行われる。ガスタービン４を回転させて仕事をした燃焼ガスは排ガスとなって、排ガス通路６である高温ダクトを経て排熱回収ボイラ５へ導入される。
【０００７】
一方、復水器８からの復水は低圧給水ポンプ９から排熱回収ボイラ内に構成されている図示していない給水系に送られる。排熱回収ボイラ５では排ガスの熱を効率よく熱回収するために、給水系と蒸気系が工夫された配置になっている。
【０００８】
排熱回収ボイラ５へ導入された排ガスは、排熱回収ボイラ５内の給水系によって熱を回収され、蒸気を発生させる。
【０００９】
上流側の高圧ドラム３０で発生した蒸気は高圧過熱器３５で過熱され、高圧主蒸気管３９を経由して蒸気タービン７の高圧部Ａへ送られ、蒸気タービン７を回転する動力として使用される。高圧部Ａで仕事をした蒸気は再利用のために低温再熱管４０を通って再熱器３６へ送られる。また中圧ドラム２５で発生した蒸気は中圧過熱器３７で過熱され、中圧主蒸気管４２を経由して低温再熱管４０へ送られ、前記高圧部Ａで仕事をした蒸気と合流して、再熱器３６へ送られる。再熱器３６で蒸気は過熱され、高温再熱管４１を通って蒸気タービン７の中圧部Ｂへ送られ、蒸気タービン７を回転する動力として使用される。さらに下流側の低圧ドラム１４で発生した蒸気は低圧過熱器３８で過熱され、低圧主蒸気管４３を通って、前記高圧部Ｂで仕事をした蒸気と合流して、蒸気タービン７の低圧部Ｃへ送られ、蒸気タービン７を回転する動力として使用される。このようにして蒸気タービン７で仕事を終えた蒸気は復水器８に送られて復水される。復水は再び低圧給水ポンプ９から排熱回収ボイラ内の給水系に送られる。
【００１０】
次に、従来技術である排熱回収ボイラの給水系を図８、図９で説明する。図８に示す排熱回収ボイラの給水系は特開平６−１８５３０９号に開示されているものである。
【００１１】
図８、図９においては、図７で説明した蒸気系は省略してあり、ここでも排熱回収ボイラは高圧、中圧、低圧からなる三重圧ボイラの例である。
【００１２】
図８において、低圧給水ポンプ９から約３０℃の給水が給水配管１０を通って、低圧蒸発器２１の下流側の排ガス流路に配置された低圧節炭器１１に送られ、排ガスの熱回収を行う。低圧節炭器１１で熱を回収して約１５０℃になった給水は給水配管１２を通って、給水調整弁１３を経由して低圧ドラム１４へ送られ、低圧蒸発器２１での熱回収によって低圧蒸気を発生するのに使用されると共に、給水調整弁１３の上流側から分岐した給水配管１５を通って高圧給水ポンプ１６へ送られる。
【００１３】
高圧給水ポンプ１６へ送られた給水は給水配管１７を通って、中圧蒸発器２６と低圧蒸発器２１の間であって中圧節炭器２２の上流の排ガス流路に配置された高圧節炭器２７（図８では高圧節炭器２７ａ、２７ｂに分割されている。）へ送られると共に、高圧給水ポンプ１６の中間段にある吐出口から抽水され、抽水管１６ａを経由して給水配管２０を通り、中圧蒸発器２６と低圧蒸発器２１の間であって高圧節炭器２７の下流の排ガス流路に配置された中圧節炭器２２へ送られる。
【００１４】
前記高圧節炭器２７及び中圧節炭器２２へ送られた給水はそれぞれ給水調整弁２９、２４を経由してそれぞれ高圧ドラム３０及び中圧ドラム２５へ送られ、高圧蒸発器３１及び中圧蒸発器２６での熱回収によって高圧蒸気及び中圧蒸気を発生するのに使用される。低圧節炭器１１へ送られ、約１５０℃になった給水の一部は再循環配管１８を通って、再循環調整弁１９を経由して低圧節炭器１１の入口側の給水配管１０に再循環され、低圧節炭器１１の入口側の給水温度を約３０℃から約５０℃まで上昇させ、低圧節炭器１１のチューブ外表面で排ガス中の水分が結露するのを防止する、いわゆる低温腐食の防止を行っている。
【００１５】
しかしながら、このような給水系においては、高圧給水ポンプ１６に低圧節炭器１１で熱回収され、約１５０℃と高温に加熱された給水が送りこまれることから、高圧給水ポンプ１６の熱変形が大きくなり、特にＤＳＳ運用を行う場合には前記熱変形によって発生する熱応力が繰り返し作用し、高圧給水ポンプ１６の破損につながるといった問題があった。
【００１６】
この対策として、図９に示すような給水系がある。図９に示す排熱回収ボイラの給水系は電気新聞平成７年５月１０日号で開示されている。
【００１７】
図９に示す装置が図８のそれとほぼ同一の装置の組み合わせからなるが、図８のそれと異なるところは、高圧給水ポンプ１６を低圧給水ポンプ９からの給水配管１０に設けたことと、図８の低圧節炭器１１と中圧節炭器２２の機能を合わせ持たせた中圧節炭器２２を低圧蒸発器２１の下流の排ガス流路に設け、高圧給水ポンプ１６の中間段からの抽水を給水配管２３と１２によって中圧ドラム２５と低圧ドラム１４に送ると共に、再循環配管１８によって再循環調整弁１９を経由して高圧給水ポンプ１６入口側に戻すようにしたことである。
【００１８】
このような給水系を構成することによって、高圧給水ポンプ１６へは、低圧給水ポンプ９からの約３０℃の給水と再循環配管１８からの約１５０℃の給水が混合して約５０℃の適温になった給水が供給され、中圧節炭器２２及び高圧節炭器２７の低温腐食を防止すると共に、高圧給水ポンプ１６の熱変形により発生する熱応力を防止するものである。
【００１９】
【発明が解決しようとする課題】
以上説明した従来技術には次のような問題点があった。
すなわち、図８に示す従来技術では、高圧給水ポンプ１６に低圧節炭器１１で熱回収して加熱された約１５０℃の高温の給水が送りこまれることから、高圧給水ポンプ１６の熱変形が大きくなり、特にＤＳＳ運用を行う場合には前記熱変形によって発生する熱応力が繰り返し作用し、高圧給水ポンプ１６の破損につながるといった問題があった。
【００２０】
次に、図９に示す従来技術では、高圧給水ポンプ１６を低圧給水ポンプ９からの給水配管１０に設けると共に、中圧節炭器２２で熱回収して加熱された約１５０℃の高温の給水を再循環配管１８を経て、高圧給水ポンプ１６の入口側の給水配管１０に戻し、低圧給水ポンプ９からの低温の約３０℃の給水に合流するようにしたことで、高圧給水ポンプ１６への入口給水温度を約５０℃に低減でき、高圧給水ポンプ１６の熱変形により発生する熱応力を防止することはできるようになった。
【００２１】
一方、図９に示す従来技術では、高圧ドラム３０への給水を高圧給水ポンプ１６から高圧蒸発器３１と中圧蒸発器２６の間の排ガス流路に配置した高圧節炭器２７によって行っているため、高圧給水ポンプ１６からの約５０℃の低温の給水は、高圧節炭器２７によって高圧ドラム３０の飽和蒸気温度である約３２０℃の近傍の給水温度（約３１０℃）まで昇温されることになる。
【００２２】
しかしながら、前記昇温される給水温度の差が大きく、熱回収による排ガス温度の降下幅が大きくなることから、高圧節炭器２７入口での排ガス温度が低い場合には、高圧節炭器２７での排ガス温度降下によって、高圧節炭器２７出口の排ガスの温度が下流の排ガス流路に配置した中圧蒸発器２６の飽和温度を下回り、中圧蒸気が発生しないことになり、熱回収が効果的に行えない。
【００２３】
従って、図９に示す従来技術においては、高圧節炭器２７での排ガス温度降下によっても中圧蒸発器２６で十分な蒸発量を得るために、高圧蒸発器３１の伝熱面積を減少することで、高圧蒸発器３１での熱回収を減少させ、高圧節炭器２７入口での排ガス温度を高くしている。しかしながら、図９に示す従来技術では図１０に示す従来の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性図に示すように、高圧節炭器２７入口での排ガス温度を上昇した分だけ熱回収が行われないことになり、約６００℃の入口ガス温度に対し、出口ガス温度が約１８０℃となり、プラント性能が低いといった問題があった。
【００２４】
また、前記の対策として前記高圧蒸発器３１の伝熱面積を減少させると共に、中圧蒸発器２６及び低圧蒸発器２１の伝熱面積を大幅に増加させ、蒸発量の減少を補うことも考えられるが、最も効率のよい高圧蒸気の発生量を制限し、効率で劣る中圧蒸気及び低圧蒸気の発生量を増加することであり、全体的なプラント性能を低下させることになり、効果的な改善ではない。
【００２５】
さらに、図９に示す従来技術では、中圧ドラム２５への給水を高圧給水ポンプ１６の中間段から低圧蒸発器２１の下流の排ガス流路に配置した中圧節炭器２２によって行っているため、中圧節炭器２２での熱回収によって約１５０℃に加熱された給水が中圧ドラム２５に給水されるが、この場合中圧ドラム２５の飽和蒸気温度が約２３０℃であることから、給水との温度差が約８０℃あり、給水によって中圧ドラム２５において過大な熱応力が発生するといった問題があった。
【００２６】
本発明の課題は、排ガスの熱回収が効率的に行え、プラント性能の高効率化ができると共に、ドラムでの過大な熱応力の発生を防止できる給水系統及び給水装置を有する排熱回収ボイラを提供することにある。
【００２７】
【発明を解決するための手段】
本発明の上記課題は次の解決手段によって達成される。
すなわち、ガスタービンからの排ガス流路に設けられ、復水器からの復水を低圧と高圧の給水ポンプにより低圧、中圧及び高圧レベルの三重圧または中圧と高圧の二重圧などの複圧に昇圧し、各圧力レベルの節炭器を経て各圧力レベルのドラムに給水する給水系と、各圧力レベルの蒸発器の伝熱管群において排ガスの熱を回収して蒸気を発生させると共に、発生した蒸気を各圧力レベルのドラムからそれぞれの圧力レベルの過熱器を経て蒸気タービンへ供給する蒸気系とから構成され、少なくとも節炭器の低温腐食を防止するため、節炭器で熱回収した高温の給水の一部を再循環配管により高圧の給水ポンプ入口の上流側の給水配管に戻す、給水の再循環系を有する排熱回収ボイラにおいて、高圧給水ポンプからの高圧ドラムへの給水を排ガス流路の２か所以上に分割して配置した高圧節炭器により行うと共に、高圧給水ポンプからの中圧ドラムへの給水を排ガス流路の２か所以上に分割して配置した中圧節炭器により行う排熱回収ボイラである。
【００２８】
本発明の上記排熱回収ボイラのより具体的な構成としては、高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第一の高圧節炭器を経て、さらに高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第二の高圧節炭器により行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の中圧節炭器を経由して行う構成、
または、高圧ドラムへの給水を高圧給水ポンプから低圧蒸発器の下流の排ガス流路に配置した第一の高圧節炭器と、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の高圧節炭器を順次経て、さらに高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の中圧節炭器を経由して行う構成、
または、高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に第二の中圧節炭器を挟んで分割して配置した第一の高圧節炭器と第二の高圧節炭器を順次経て、高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した前記第二の中圧節炭器を経由して行う構成、
または、高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に第一の中圧節炭器を挟んで分割して配置した第一の高圧節炭器と第二の高圧節炭器を順次経て、高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から中圧蒸発器と低圧蒸発器の間の排ガス流路に前記第二の高圧節炭器を挟んで分割して配置した前記第一の中圧節炭器と第二の中圧節炭器を順次経由して行う構成としても良い。
【００２９】
また、本発明の上記排熱回収ボイラにおいて、高圧節炭器と中圧節炭器をそれぞれ二つ以上に分割し、各分割された高圧節炭器の少なくとも一つを高圧蒸発器と中圧蒸発器の間の排ガス流路に配置し、他の少なくとも一つの高圧節炭器を中圧蒸発器と低圧蒸発器の間または低圧蒸発器の下流側の排ガス流路に配置し、各分割された中圧節炭器の少なくとも一つを中圧蒸発器と低圧蒸発器の間の排ガス流路に配置し、他の少なくとも一つの中圧節炭器を低圧蒸発器の下流側の排ガス流路に配置すること、
または、二つに分割した中圧節炭器の少なくとも第一の中圧節炭器の出口給水を低圧ドラムと第二の中圧節炭器にそれぞれ別個に供給し、第二の中圧節炭器の出口給水を中圧ドラムに供給する構成としても良い。
【００３０】
また、本発明の排熱回収ボイラにおいては、低圧蒸発器の下流側の排ガス流路に配置される高圧節炭器と中圧節炭器または中圧蒸発器と低圧蒸発器の間の排ガス流路に配置される高圧節炭器と中圧節炭器をそれぞれ排ガス流れに対して並列に配置することができる。
【００３１】
【作用】
本発明によれば、高圧ドラムへの給水をガス流路の２か所以上に分割して配置した高圧節炭器により行うので、高圧節炭器において効率的な熱回収が行える。また、中圧ドラムへの給水をガス流路の２か所以上に分割して配置した中圧節炭器により行うので、中圧節炭器において効率的な熱回収が行えると共に、高圧給水ポンプからの低温の給水を中圧ドラムで熱応力が発生しない程度の適正な温度に昇温して中圧ドラムに給水することができる。
【００３２】
さらに本発明によれば、図５、図６の本発明の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性図に示すように、ボイラ入口の排ガス温度約６００℃に対してボイラ出口で約１００℃と、排ガスの熱回収が、図１０に示す従来技術のプラントに比べ約２０％増加するので、プラント性能において約５％の高効率化ができる。
【００３３】
さらに、高圧節炭器及び中圧節炭器の分割を総伝熱面積あるいは総熱回収量を一定として行うことで、本発明を既存の設備の改善にも実施できる。
【００３４】
【発明の実施の形態】
以下、図面を参照して本発明の一実施例について説明する。
図１に本発明の一実施例である排熱回収ボイラの給水系統図を示し、各過熱器については記載していない。
【００３５】
図１において、排熱回収ボイラの排ガス流路の下流側から上流側に順に中圧一次節炭器２２ａ、低圧蒸発器２１、高圧一次節炭器２７ａ、中圧二次節炭器２２ｂ、中圧蒸発器２６、高圧二次節炭器２７ｂ、高圧蒸発器３１が配置されている。そして、図１において、排熱回収ボイラへの給水入口側に低圧給水ポンプ９を設置し、低圧給水ポンプ９からの出口給水配管１０を直接に高圧給水ポンプ１６の入口に接続している。高圧給水ポンプ１６により高圧一次節炭器２７ａを経て高圧二次節炭器２７ｂを通り、高圧ドラム３０に給水が行われる。
【００３６】
また、高圧給水ポンプ１６中間段から低圧蒸発器２１の下流の排ガス流路に配置された中圧一次節炭器２２ａを経て、中圧二次節炭器２２ｂを通り中圧ドラム２５に給水が行われる。
【００３７】
高圧給水ポンプ１６からの約５０℃の給水は、高圧一次節炭器２７ａでの熱回収によって約２２０℃に昇温された後、さらに高圧二次節炭器２７ｂでの熱回収によって約３１０℃に昇温され、高圧ドラム３０に給水される。従って、従来例のように高圧節炭器での過大な熱回収によって排ガス温度が極端に低下することがない。
【００３８】
また、高圧給水ポンプ１６中間段からの約５０℃の給水は、中圧一次節炭器２２ａでの熱回収によって約１５０℃に昇温された後、中圧二次節炭器２２ｂでの熱回収によって約２２０℃に昇温され、中圧ドラム２５に給水される。ここで中圧蒸発器２６の飽和温度は約２３０℃であることから、給水温度との差は約１０℃まで低減でき、熱応力の発生が防止される。
【００３９】
本発明の実施例によって、図５の本発明の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性図に示すように、ボイラ入口の排ガス温度約６００℃に対してボイラ出口で約１００℃と、排ガスの熱回収が効率的に行える。
【００４０】
なお、本実施例では、中圧蒸発器２６と低圧蒸発器２１の間の排ガス流路おいて、高圧一次節炭器２７ａを中圧二次節炭器２２ｂの下流に配置したが、高圧一次節炭器２７ａを中圧二次節炭器２２ｂのガス上流又は並列に配置しても排ガスの熱回収において問題がないため、同様の効果が得られる。
【００４１】
本発明の他の実施例を図２、図３、図４を用いてそれぞれ説明する。
図２に示す実施例では、排熱回収ボイラの排ガス流路の下流側から上流側に順に高圧一次節炭器２７ａ、中圧一次節炭器２２ａ、低圧蒸発器２１、高圧二次節炭器２７ｂ、中圧二次節炭器２２ｂ、中圧蒸発器２６、高圧三次節炭器２７ｃおよび高圧蒸発器３１が配置されている。
【００４２】
そして、排熱回収ボイラへの給水入口側に低圧給水ポンプ９を設置し、低圧給水ポンプ９からの出口給水配管１０を直接に高圧給水ポンプ１６の入口に接続し、高圧給水ポンプ１６により高圧一次節炭器２７ａと高圧二次節炭器２７ｂを順次経て、高圧三次節炭器２７ｃを通り高圧ドラム３０に給水が行われる。
【００４３】
また、高圧給水ポンプ１６中間段からは中圧一次節炭器２２ａと中圧二次節炭器２２ｂを順次通り、中圧ドラム２５に給水が行われる。
【００４４】
高圧給水ポンプ１６からの約５０℃の給水は、高圧一次節炭器２７ａでの熱回収によって約１２０℃に昇温された後、高圧二次節炭器２７ｂでの熱回収によって約２１０℃に昇温され、さらに高圧三次節炭器２７ｃでの熱回収によって約３１０℃に昇温されて高圧ドラム３０に給水される。従って、従来例のように高圧節炭器での過大な熱回収によって排ガス温度が極端に低下することがなく、各節炭器で無理なく効率的に熱回収が行われる。
【００４５】
また、高圧給水ポンプ１６中間段からの約５０℃の給水は、中圧一次節炭器２２ａでの熱回収によって約１５０℃に昇温された後、中圧二次節炭器２２ｂでの熱回収によって約２２０℃に昇温され、中圧ドラム２５に給水される。ここで中圧蒸発器２６の飽和温度は約２３０℃であることから、給水温度との差は約１０℃まで低減でき、熱応力の発生が防止される。
【００４６】
本発明の前記実施例によって、図６は本発明の図２に示す実施例の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性図に示すように、ボイラ入口の排ガス温度約６００℃に対してボイラ出口で約１００℃と、排ガスの熱回収が効率的に行える。
【００４７】
なお、本実施例では低圧蒸発器２１の下流及び中圧蒸発器２６と低圧蒸発器２１の間の排ガス流路おいて、高圧一次節炭器２７ａを中圧一次節炭器２２ａの下流側に配置し、高圧二次節炭器２７ｂを中圧二次節炭器２２ｂの下流側に配置したが、高圧一次節炭器２７ａ及び高圧二次節炭器２７ｂをそれぞれ中圧一次節炭器２２ａ及び中圧二次節炭器２２ｂの上流または並列に配置しても排ガスの熱回収において問題がないため、同様の効果が得られる。
【００４８】
次に、図３に示す実施例では、排熱回収ボイラの排ガス流路の下流側から上流側に順に中圧一次節炭器２２ａ、低圧蒸発器２１、高圧一次節炭器２７ａ、中圧二次節炭器２２ｂ、高圧二次節炭器２７ｂ、中圧蒸発器２６、高圧三次節炭器２７ｃおよび高圧蒸発器３１が配置されている。
【００４９】
排熱回収ボイラへの給水入口側に低圧給水ポンプ９を設置し、低圧給水ポンプ９からの出口給水配管１０を直接に高圧給水ポンプ１６の入口に接続し、高圧給水ポンプ１６により高圧一次節炭器２７ａと高圧二次節炭器２７ｂを順次経て、さらに高圧三次節炭器２７ｃによって高圧ドラム３０に給水が行われる。
【００５０】
また、高圧給水ポンプ１６の中間段からは中圧一次節炭器２２ａと中圧二次節炭器２２ｂを順次経て、中圧ドラム２５に給水が行われる。
【００５１】
高圧給水ポンプ１６からの約５０℃の給水は、高圧一次節炭器２７ａでの熱回収によって約１２０℃に昇温された後、高圧二次節炭器２７ｂでの熱回収によって約２１０℃に昇温され、さらに高圧三次節炭器２７ｃでの熱回収によって約３１０℃に昇温されて高圧ドラム３０に給水される。従って、従来例のように高圧節炭器での過大な熱回収によって排ガス温度が極端に低下することがなく、各節炭器２７ａ〜２７ｃで無理なく効率的に熱回収が行われる。
【００５２】
また、高圧給水ポンプ１６中間段からの約５０℃の給水は、中圧一次節炭器２２ａでの熱回収によって約１５０℃に昇温された後、中圧二次節炭器２２ｂでの熱回収によって約２２０℃に昇温され、中圧ドラム２５に給水される。ここで中圧蒸発器２６の飽和温度は約２３０℃であることから、給水温度との差は約１０℃まで低減でき、熱応力の発生が防止される。
【００５３】
本発明の図３に示す実施例の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性は、図示していないが、ボイラ入口の約６００℃の排ガスがボイラ出口で約１００℃になる。
【００５４】
次に、図４に示す実施例では、排熱回収ボイラの排ガス流路の下流側から上流側に順に低圧節炭器１１、低圧蒸発器２１、高圧一次節炭器２７ａ、中圧一次節炭器２２ａ、高圧二次節炭器２７ｂ、中圧二次節炭器２２ｂ、中圧蒸発器２６、高圧三次節炭器２７ｃおよび高圧蒸発器３１が配置されている。
【００５５】
排熱回収ボイラへの給水入口側の低圧給水ポンプ９からの出口給水配管１０を直接に高圧給水ポンプ１６の入口に接続し、高圧給水ポンプ１６の上流から分岐して低圧節炭器１１を経て、低圧ドラム１４に給水が行われる。また高圧給水ポンプ１６により高圧一次節炭器２７ａと高圧二次節炭器２７ｂを順次経て、さらに高圧三次節炭器２７ｃを経由して高圧ドラム３０に給水が行われる。
【００５６】
また、高圧給水ポンプ１６中間段から中圧一次節炭器２２ａと中圧二次節炭器２２ｂを順次経由して中圧ドラム２５に給水が行われる。
【００５７】
また、中圧一次節炭器２２ａと中圧二次節炭器２２ｂを接続する給水配管２３ｂから再循環配管１８が分岐され、高圧給水ポンプ１６入口の給水配管１０に戻される。再循環配管１８の給水配管１０への接続部は、給水配管１０から分岐した低圧節炭器１１への給水配管２０の分岐部より上流側にある。そして、再循環配管１８からの給水は、低圧給水ポンプ９からの給水の温度を約５０℃とし、各節炭器の低温腐食を防止している。
【００５８】
高圧給水ポンプ１６からの約５０℃の給水は、高圧一次節炭器２７ａでの熱回収によって約１２０℃に昇温された後、高圧二次節炭器２７ｂでの熱回収によって約２１０℃に昇温され、さらに高圧三次節炭器２７ｃでの熱回収によって約３１０℃に昇温され高圧ドラム３０に給水される。従って、従来例のように高圧節炭器での過大な熱回収によって排ガス温度が極端に低下することがなく、各節炭器で無理なく効率的に熱回収が行われる。
【００５９】
また、高圧給水ポンプ１６中間段からの約５０℃の給水は、中圧一次節炭器２２ａでの熱回収によって約１５０℃に昇温された後、中圧二次節炭器２２ｂでの熱回収によって約２２０℃に昇温され、中圧ドラム２５に給水される。ここで、中圧蒸発器２６の飽和温度は約２３０℃であることから、給水温度との差は約１０℃まで低減でき、熱応力の発生が防止される。
【００６０】
中圧蒸発器２６と低圧蒸発器２１の間の排ガス流路に配置される高圧節炭器２７と中圧節炭器２２は互いにその排ガス流路内での配置を置き換えてもまたは並列に配置しても排ガスの熱回収において問題がないため、同様の効果が得られる。
【００６１】
【発明の効果】
本発明によれば、高圧ドラムへの給水をガス流路の２か所以上に分割して配置した高圧節炭器を経由して行い、また、中圧ドラムへの給水をガス流路の２か所以上に分割して配置した中圧節炭器を経由して行うので、排ガスの熱回収が効率的に行え、プラント性能の高効率化ができると共に、ドラムでの過大な熱応力の発生を防止できる給水系統及び給水装置を有する排熱回収ボイラを提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施例の排熱回収ボイラの給水系統を示す図である。
【図２】本発明の一実施例の排熱回収ボイラの給水系統を示す図である。
【図３】本発明の一実施例の排熱回収ボイラの給水系統を示す図である。
【図４】本発明の一実施例の排熱回収ボイラの給水系統を示す図である。
【図５】本発明の一実施例の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性を示す図である。
【図６】本発明の一実施例の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性を示す図である。
【図７】排熱回収ボイラを有する複合発電プラントの概略の系統を示す図である。
【図８】従来技術の排熱回収ボイラの給水系統を示す図である。
【図９】従来技術の排熱回収ボイラの給水系統を示す図である。
【図１０】従来技術の給水系統を有する排熱回収ボイラにおける排ガス温度及び蒸気及び給水温度特性を示す図である。
【符号の説明】
９低圧給水ポンプ１０給水配管
１１低圧節炭器１４低圧ドラム
１６高圧給水ポンプ１８再循環配管
１９再循環調節弁２１低圧蒸発器
２２中圧節炭器２５中圧ドラム
２６中圧蒸発器２７高圧節炭器
３０高圧ドラム３１高圧蒸発器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust heat recovery boiler in which a water supply system and a water supply device are arranged so that heat recovery can be performed efficiently and plant performance can be improved in a combined power plant.
[0002]
[Prior art]
For example, as shown in the schematic system diagram of the combined power plant in FIG. 7, the combined power plant includes a gas turbine open cycle unit, an exhaust heat recovery boiler, a steam turbine cycle unit, and a generator. The exhaust heat recovery boiler of FIG. 7 is an example of a triple pressure boiler composed of high pressure, medium pressure, and low pressure.
[0003]
In the gas turbine open cycle section, power is generated by the gas turbine 4, and exhaust gas worked by the gas turbine 4 is discharged to the exhaust gas passage 6. The discharged high-temperature exhaust gas is introduced into the exhaust heat recovery boiler 5 through the exhaust gas passage 6, and the heat in the exhaust gas is recovered. In the steam turbine cycle section, cycle power generation is performed by the steam turbine 7 using steam generated in the exhaust heat recovery boiler.
[0004]
Such a combined power plant has high power generation efficiency for performing combined power generation by the gas turbine 4 and the steam turbine 7, and the power generation by the gas turbine 4 is excellent in load responsiveness. There are features such as high follow-up to changes. In particular, this is effective for the operation that performs the recent high frequency start / stop (Daily Start Stop, hereinafter referred to as DSS).
[0005]
A steam supply system (hereinafter referred to as a steam system) to the steam turbine of the exhaust heat recovery boiler in the combined power plant will be described with reference to FIG. In FIG. 7, the description of a water supply device (hereinafter referred to as a water supply system) configured in the exhaust heat recovery boiler 5 is omitted except for the drum.
[0006]
In the gas turbine 4, the combustion air from the air supply pipe 1 and the fuel from the fuel supply pipe 2 are mixed in the combustor, and the gas turbine 4 is rotated by the combustion gas generated by the combustion. Power generation is performed. The combustion gas that has worked by rotating the gas turbine 4 becomes exhaust gas, and is introduced into the exhaust heat recovery boiler 5 through the high-temperature duct that is the exhaust gas passage 6.
[0007]
On the other hand, the condensate from the condenser 8 is sent from the low-pressure feed water pump 9 to a water supply system (not shown) configured in the exhaust heat recovery boiler. In the exhaust heat recovery boiler 5, in order to efficiently recover the heat of the exhaust gas, the water supply system and the steam system are devised.
[0008]
The exhaust gas introduced into the exhaust heat recovery boiler 5 recovers heat by the feed water system in the exhaust heat recovery boiler 5 to generate steam.
[0009]
The steam generated in the high-pressure drum 30 on the upstream side is superheated by the high-pressure superheater 35, sent to the high-pressure part A of the steam turbine 7 via the high-pressure main steam pipe 39, and used as power for rotating the steam turbine 7. . The steam that has worked in the high pressure section A is sent to the reheater 36 through the low temperature reheat pipe 40 for reuse. The steam generated in the intermediate pressure drum 25 is superheated by the intermediate pressure superheater 37, sent to the low temperature reheat pipe 40 through the intermediate pressure main steam pipe 42, and merged with the steam worked in the high pressure section A. To the reheater 36. The steam is superheated by the reheater 36, is sent to the intermediate pressure part B of the steam turbine 7 through the high-temperature reheat pipe 41, and is used as power for rotating the steam turbine 7. Further, the steam generated in the low-pressure drum 14 on the downstream side is superheated in the low-pressure superheater 38, passes through the low-pressure main steam pipe 43, and merges with the steam that has worked in the high-pressure part B. To be used as power for rotating the steam turbine 7. In this way, the steam that has finished work in the steam turbine 7 is sent to the condenser 8 to be condensed. The condensate is sent again from the low-pressure feed pump 9 to the feed water system in the exhaust heat recovery boiler.
[0010]
Next, the water supply system of the exhaust heat recovery boiler, which is a conventional technology, will be described with reference to FIGS. The water supply system of the exhaust heat recovery boiler shown in FIG. 8 is disclosed in JP-A-6-185309.
[0011]
8 and 9, the steam system described in FIG. 7 is omitted, and the exhaust heat recovery boiler is also an example of a triple pressure boiler composed of high pressure, medium pressure, and low pressure.
[0012]
In FIG. 8, feed water of about 30 ° C. is fed from the low-pressure feed water pump 9 through the feed water pipe 10 to the low-pressure economizer 11 disposed in the exhaust gas flow path on the downstream side of the low-pressure evaporator 21 to recover the heat of the exhaust gas. I do. The feed water that has recovered heat at the low-pressure economizer 11 and has reached about 150 ° C. is sent to the low-pressure drum 14 via the feed water adjustment valve 13 through the feed water pipe 12, and by heat recovery at the low-pressure evaporator 21. It is used to generate low-pressure steam and is sent to a high-pressure feed pump 16 through a feed water pipe 15 branched from the upstream side of the feed water adjustment valve 13.
[0013]
The feed water sent to the high-pressure feed water pump 16 passes through the feed water pipe 17 and is located between the intermediate-pressure evaporator 26 and the low-pressure evaporator 21 and in the exhaust gas passage upstream of the intermediate-pressure economizer 22. While being sent to the charcoal unit 27 (divided into the high-pressure economizers 27a and 27b in FIG. 8), water is extracted from the discharge port in the intermediate stage of the high-pressure feed pump 16, and the feed water pipe is routed through the drain pipe 16a. 20, the intermediate pressure economizer 22 is disposed in the exhaust gas flow path between the intermediate pressure evaporator 26 and the low pressure evaporator 21 and downstream of the high pressure economizer 27.
[0014]
The feed water sent to the high-pressure economizer 27 and the medium-pressure economizer 22 is sent to the high-pressure drum 30 and the intermediate-pressure drum 25 via the feed water adjustment valves 29 and 24, respectively, and the high-pressure evaporator 31 and the intermediate pressure It is used to generate high pressure steam and medium pressure steam by heat recovery in the evaporator 26. A part of the feed water sent to the low-pressure economizer 11 and having reached about 150 ° C. passes through the recirculation pipe 18 and passes through the recirculation control valve 19 to the feed water pipe 10 on the inlet side of the low-pressure economizer 11. It is recirculated and raises the feed water temperature on the inlet side of the low-pressure economizer 11 from about 30 ° C. to about 50 ° C., and prevents the moisture in the exhaust gas from condensing on the outer surface of the tube of the low-pressure economizer 11. Prevents low temperature corrosion.
[0015]
However, in such a water supply system, heat is recovered in the high-pressure feed pump 16 by the low-pressure economizer 11, and the feed water heated to a high temperature of about 150 ° C. is sent to the high-pressure feed pump 16. In particular, when performing DSS operation, there is a problem that the thermal stress generated by the thermal deformation acts repeatedly, leading to damage to the high-pressure feed pump 16.
[0016]
As a countermeasure, there is a water supply system as shown in FIG. The water supply system of the exhaust heat recovery boiler shown in FIG. 9 is disclosed in the electric newspaper May 10, 1995.
[0017]
The apparatus shown in FIG. 9 is composed of a combination of substantially the same apparatus as that shown in FIG. 8, but is different from that shown in FIG. 8 in that the high-pressure feed water pump 16 is provided in the feed water pipe 10 from the low-pressure feed water pump 9. The medium-pressure economizer 22 having the functions of the low-pressure economizer 11 and the medium-pressure economizer 22 are provided in the exhaust gas flow path downstream of the low-pressure evaporator 21, and water is extracted from the intermediate stage of the high-pressure feed pump 16. Is fed to the intermediate-pressure drum 25 and the low-pressure drum 14 through the water supply pipes 23 and 12, and is returned to the inlet side of the high-pressure water supply pump 16 through the recirculation adjustment valve 19 by the recirculation pipe 18.
[0018]
By configuring such a water supply system, about 30 ° C. water supplied from the low pressure water supply pump 9 and about 150 ° C. water supplied from the recirculation pipe 18 are mixed with the high pressure water supply pump 16 to an appropriate temperature of about 50 ° C. Thus, the low pressure corrosion of the medium pressure economizer 22 and the high pressure economizer 27 is prevented, and the thermal stress generated by the thermal deformation of the high pressure feed pump 16 is prevented.
[0019]
[Problems to be solved by the invention]
The conventional technology described above has the following problems.
That is, in the prior art shown in FIG. 8, the high-pressure feed pump 16 is supplied with high-temperature feed water of about 150 ° C. heated and recovered by the low-pressure economizer 11. In particular, when performing DSS operation, there is a problem that the thermal stress generated by the thermal deformation acts repeatedly, leading to damage to the high-pressure feed pump 16.
[0020]
Next, in the prior art shown in FIG. 9, the high-pressure feed water pump 16 is provided in the feed water pipe 10 from the low-pressure feed water pump 9, and the high-temperature feed water having a temperature of about 150 ° C. heated and recovered by the medium pressure economizer 22. Is returned to the water supply pipe 10 on the inlet side of the high-pressure feed pump 16 through the recirculation pipe 18 and joined to the low-temperature feed water of about 30 ° C. from the low-pressure feed pump 9. The inlet water supply temperature can be reduced to about 50 ° C., and the thermal stress generated by the thermal deformation of the high pressure water supply pump 16 can be prevented.
[0021]
On the other hand, in the prior art shown in FIG. 9, water supply to the high-pressure drum 30 is performed by the high-pressure economizer 27 arranged in the exhaust gas flow path between the high-pressure evaporator 31 and the medium-pressure evaporator 26 from the high-pressure feed water pump 16. Therefore, the low-temperature feed water of about 50 ° C. from the high-pressure feed pump 16 is heated by the high-pressure economizer 27 to a feed water temperature (about 310 ° C.) in the vicinity of about 320 ° C. that is the saturated steam temperature of the high-pressure drum 30. It will be.
[0022]
However, since the difference in the temperature of the feed water to be raised is large and the exhaust gas temperature drop due to heat recovery is large, if the exhaust gas temperature at the inlet of the high pressure economizer 27 is low, the high pressure economizer 27 As the exhaust gas temperature drops, the temperature of the exhaust gas at the outlet of the high pressure economizer 27 falls below the saturation temperature of the intermediate pressure evaporator 26 arranged in the downstream exhaust gas flow path, so that no intermediate pressure steam is generated, and heat recovery is effective. Cannot be done.
[0023]
Therefore, in the prior art shown in FIG. 9, the heat transfer area of the high pressure evaporator 31 is reduced in order to obtain a sufficient amount of evaporation in the intermediate pressure evaporator 26 even when the exhaust gas temperature drops in the high pressure economizer 27. Thus, the heat recovery at the high pressure evaporator 31 is reduced, and the exhaust gas temperature at the inlet of the high pressure economizer 27 is increased. However, in the prior art shown in FIG. 9, the exhaust gas temperature at the inlet of the high pressure economizer 27 is increased as shown in the exhaust gas temperature and steam and feed water temperature characteristic diagram in the exhaust heat recovery boiler having the conventional water supply system shown in FIG. As a result, heat recovery is not performed, and the outlet gas temperature is about 180 ° C. with respect to the inlet gas temperature of about 600 ° C., resulting in poor plant performance.
[0024]
Further, as a countermeasure, it is conceivable that the heat transfer area of the high-pressure evaporator 31 is reduced and the heat transfer areas of the medium-pressure evaporator 26 and the low-pressure evaporator 21 are greatly increased to compensate for the decrease in the evaporation amount. Is to limit the generation of the most efficient high-pressure steam and increase the generation of inferior medium-pressure and low-pressure steam, which will reduce overall plant performance and effectively improve is not.
[0025]
Furthermore, in the prior art shown in FIG. 9, water supply to the intermediate pressure drum 25 is performed by the intermediate pressure economizer 22 disposed in the exhaust gas flow path downstream of the low pressure evaporator 21 from the intermediate stage of the high pressure feed water pump 16. The water supply heated to about 150 ° C. by heat recovery in the medium pressure economizer 22 is supplied to the intermediate pressure drum 25. In this case, since the saturated steam temperature of the intermediate pressure drum 25 is about 230 ° C., There was a problem that the temperature difference from the water supply was about 80 ° C., and excessive thermal stress was generated in the intermediate pressure drum 25 by the water supply.
[0026]
An object of the present invention is to provide an exhaust heat recovery boiler having a water supply system and a water supply device that can efficiently recover heat of exhaust gas, increase plant performance, and prevent the generation of excessive thermal stress in the drum. It is to provide.
[0027]
[Means for Solving the Invention]
The above object of the present invention is achieved by the following means.
That is, it is provided in the exhaust gas flow path from the gas turbine, and the condensate from the condenser is discharged by a low-pressure and high-pressure feed water pump to a low pressure, a medium pressure and a high pressure level of triple pressure or a medium pressure and a high pressure double pressure. In the water supply system that supplies water to the drum at each pressure level through the economizer at each pressure level and the heat transfer tube group of the evaporator at each pressure level, the heat of the exhaust gas is recovered to generate steam and generated High-temperature steam recovered from the economizer in order to prevent low-temperature corrosion of the economizer at least. In a waste heat recovery boiler with a feed water recirculation system that returns a part of the feed water to the feed water pipe upstream of the high pressure feed pump inlet by the recirculation pipe, the feed water from the high pressure feed pump to the high pressure drum is discharged. A medium pressure node that is divided into two or more places in the exhaust gas flow path, and the water supply from the high pressure feed pump to the medium pressure drum is divided into two or more places in the exhaust gas flow path. This is a waste heat recovery boiler that uses a charcoal.
[0028]
As a more specific configuration of the exhaust heat recovery boiler of the present invention, the first high-pressure economizer in which feed water to the high-pressure drum is disposed in the exhaust gas flow path between the medium-pressure evaporator and the low-pressure evaporator from the high-pressure feed pump And a second high-pressure economizer disposed in the exhaust gas flow path between the high-pressure evaporator and the intermediate-pressure evaporator, and water supply to the intermediate-pressure drum from the intermediate stage of the high-pressure feed pump to the low-pressure evaporator It goes through the first medium pressure economizer arranged in the exhaust gas flow path downstream from the first intermediate pressure economizer arranged in the exhaust gas flow path between the medium pressure evaporator and the low pressure evaporator. Constitution,
Alternatively, the feed water to the high-pressure drum is arranged in the exhaust gas passage between the first high-pressure economizer and the intermediate-pressure evaporator and the low-pressure evaporator, arranged in the exhaust gas passage downstream of the low-pressure evaporator from the high-pressure feed pump. It goes through the second high-pressure economizer sequentially, and further via the third high-pressure economizer arranged in the exhaust gas flow path between the high-pressure evaporator and the medium-pressure evaporator, and also supplies water to the intermediate-pressure drum. From the intermediate stage of the high-pressure feed pump, through the first medium-pressure economizer arranged in the exhaust gas flow path downstream of the low-pressure evaporator, the second arranged in the exhaust gas flow path between the intermediate-pressure evaporator and the low-pressure evaporator Configuration done via medium pressure economizer,
Or the 1st high pressure economizer which divided | segmented and arrange | positioned the feed water to a high pressure drum from the high pressure feed water pump to the exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator with the second intermediate pressure economizer interposed And the second high-pressure economizer, and then through the third high-pressure economizer arranged in the exhaust gas flow path between the high-pressure evaporator and the medium-pressure evaporator, From the intermediate stage of the high pressure feed pump, through the first medium pressure economizer arranged in the exhaust gas flow path downstream of the low pressure evaporator, the second arranged in the exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator The configuration to be performed via the medium pressure economizer,
Or the 1st high pressure economizer which divided | segmented and arrange | positioned the water supply to a high pressure drum from the high pressure feed pump to the exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator with the first intermediate pressure economizer interposed And the second high-pressure economizer, and then through the third high-pressure economizer arranged in the exhaust gas flow path between the high-pressure evaporator and the medium-pressure evaporator, The first medium-pressure economizer and the second medium-pressure economizer arranged separately from the intermediate stage of the high-pressure feed water pump with the second high-pressure economizer sandwiched in the exhaust gas flow path between the intermediate-pressure evaporator and the low-pressure evaporator It is good also as a structure performed via a medium pressure economizer sequentially.
[0029]
In the exhaust heat recovery boiler of the present invention, the high pressure economizer and the medium pressure economizer are each divided into two or more, and at least one of the divided high pressure economizers is divided into the high pressure evaporator and the intermediate pressure economizer. Arranged in the exhaust gas flow path between the evaporators, and arranged at least one other high-pressure economizer between the medium pressure evaporator and the low pressure evaporator or in the exhaust gas flow path downstream of the low pressure evaporator, each divided At least one medium pressure economizer is disposed in the exhaust gas flow path between the medium pressure evaporator and the low pressure evaporator, and at least one other medium pressure economizer is disposed in the exhaust gas flow path downstream of the low pressure evaporator. To place in,
Or, the outlet water of at least the first medium pressure economizer of the medium pressure economizer divided into two is separately supplied to the low pressure drum and the second medium pressure economizer, respectively, It is good also as a structure which supplies the outlet water supply of a charcoal to an intermediate pressure drum.
[0030]
In the exhaust heat recovery boiler of the present invention, the exhaust gas flow between the high pressure economizer and the intermediate pressure economizer or the intermediate pressure evaporator and the low pressure evaporator disposed in the exhaust gas flow path downstream of the low pressure evaporator. A high-pressure economizer and a medium-pressure economizer arranged in the road can be arranged in parallel to the exhaust gas flow.
[0031]
[Action]
According to the present invention, the water supply to the high-pressure drum is performed by the high-pressure economizer arranged in two or more locations in the gas flow path, so that efficient heat recovery can be performed in the high-pressure economizer. In addition, since the water supply to the medium pressure drum is performed by the medium pressure economizer arranged in two or more places in the gas flow path, efficient heat recovery can be performed in the medium pressure economizer, and the high pressure feed pump Can be supplied to the intermediate pressure drum by raising the temperature of the low-temperature water supply to an appropriate temperature that does not generate thermal stress in the intermediate pressure drum.
[0032]
Further, according to the present invention, as shown in the exhaust gas temperature and steam and feed water temperature characteristic diagrams in the exhaust heat recovery boiler having the feed water system of the present invention in FIGS. 5 and 6, the exhaust gas temperature at the boiler inlet is about 600 ° C. About 100 ° C. at the boiler outlet, the heat recovery of the exhaust gas is increased by about 20% as compared with the prior art plant shown in FIG. 10, so that the efficiency of the plant can be improved by about 5%.
[0033]
Furthermore, by dividing the high pressure economizer and the medium pressure economizer with the total heat transfer area or the total heat recovery amount being constant, the present invention can be implemented to improve existing facilities.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a water supply system diagram of an exhaust heat recovery boiler according to an embodiment of the present invention, and each superheater is not described.
[0035]
In FIG. 1, a medium pressure primary economizer 22a, a low pressure evaporator 21, a high pressure primary economizer 27a, an intermediate pressure secondary economizer 22b, an intermediate pressure are sequentially arranged from the downstream side to the upstream side of the exhaust gas flow path of the exhaust heat recovery boiler. An evaporator 26, a high-pressure secondary economizer 27b, and a high-pressure evaporator 31 are arranged. In FIG. 1, a low-pressure feed pump 9 is installed on the feed water inlet side to the exhaust heat recovery boiler, and an outlet feed pipe 10 from the low-pressure feed pump 9 is directly connected to the inlet of the high-pressure feed pump 16. The high-pressure feed water pump 16 feeds water to the high-pressure drum 30 through the high-pressure primary economizer 27a and the high-pressure secondary economizer 27b.
[0036]
Further, water is supplied from the intermediate stage of the high-pressure feed pump 16 to the intermediate-pressure drum 25 through the intermediate-pressure secondary economizer 22b via the intermediate-pressure primary economizer 22a disposed in the exhaust gas flow path downstream of the low-pressure evaporator 21. Is called.
[0037]
The feed water at about 50 ° C. from the high pressure feed water pump 16 is heated to about 220 ° C. by heat recovery at the high pressure primary economizer 27a, and further increased to about 310 ° C. by heat recovery at the high pressure secondary economizer 27b. The temperature is raised and water is supplied to the high-pressure drum 30. Therefore, the exhaust gas temperature does not extremely decrease due to excessive heat recovery in the high pressure economizer as in the conventional example.
[0038]
In addition, about 50 ° C. feed water from the intermediate stage of the high pressure feed water pump 16 is heated to about 150 ° C. by heat recovery at the intermediate pressure primary economizer 22a, and then recovered at the intermediate pressure secondary economizer 22b. The temperature is raised to about 220 ° C. and water is supplied to the intermediate pressure drum 25. Here, since the saturation temperature of the medium pressure evaporator 26 is about 230 ° C., the difference from the feed water temperature can be reduced to about 10 ° C., and the generation of thermal stress is prevented.
[0039]
According to the embodiment of the present invention, as shown in the exhaust gas temperature and steam and feed water temperature characteristic diagram of the exhaust heat recovery boiler having the feed water system of the present invention of FIG. About 100 ° C., heat recovery of exhaust gas can be performed efficiently.
[0040]
In the present embodiment, the high-pressure primary economizer 27a is arranged downstream of the intermediate-pressure secondary economizer 22b in the exhaust gas flow path between the intermediate-pressure evaporator 26 and the low-pressure evaporator 21, but the high-pressure primary economizer Even if the charcoal unit 27a is arranged upstream or in parallel with the medium pressure secondary economizer 22b, there is no problem in the heat recovery of the exhaust gas, and the same effect can be obtained.
[0041]
Other embodiments of the present invention will be described with reference to FIGS.
In the embodiment shown in FIG. 2, the high-pressure primary economizer 27a, the medium-pressure primary economizer 22a, the low-pressure evaporator 21, and the high-pressure secondary economizer 27b are sequentially arranged from the downstream side to the upstream side of the exhaust gas flow path of the exhaust heat recovery boiler. An intermediate pressure secondary economizer 22b, an intermediate pressure evaporator 26, a high pressure tertiary economizer 27c, and a high pressure evaporator 31 are arranged.
[0042]
Then, a low-pressure feed pump 9 is installed on the feed water inlet side to the exhaust heat recovery boiler, an outlet feed pipe 10 from the low-pressure feed pump 9 is directly connected to the inlet of the high-pressure feed pump 16, and the high-pressure feed pump 16 Water is supplied to the high-pressure drum 30 through the economizer 27a and the high-pressure secondary economizer 27b in sequence, through the high-pressure tertiary economizer 27c.
[0043]
Further, water is supplied to the intermediate pressure drum 25 from the intermediate stage of the high pressure feed pump 16 through the intermediate pressure primary economizer 22a and the intermediate pressure secondary economizer 22b in order.
[0044]
The feed water at about 50 ° C. from the high pressure feed water pump 16 is heated to about 120 ° C. by heat recovery at the high pressure primary economizer 27a and then rises to about 210 ° C. by heat recovery at the high pressure secondary economizer 27b. Then, the temperature is raised to about 310 ° C. by heat recovery in the high pressure tertiary economizer 27 c and supplied to the high pressure drum 30. Therefore, the exhaust gas temperature does not extremely decrease due to excessive heat recovery in the high-pressure economizer as in the conventional example, and heat recovery is performed efficiently and efficiently in each economizer.
[0045]
In addition, about 50 ° C. feed water from the intermediate stage of the high pressure feed water pump 16 is heated to about 150 ° C. by heat recovery at the intermediate pressure primary economizer 22a, and then recovered at the intermediate pressure secondary economizer 22b. The temperature is raised to about 220 ° C. and water is supplied to the intermediate pressure drum 25. Here, since the saturation temperature of the medium pressure evaporator 26 is about 230 ° C., the difference from the feed water temperature can be reduced to about 10 ° C., and the generation of thermal stress is prevented.
[0046]
According to the above embodiment of the present invention, FIG. 6 shows the exhaust gas temperature and steam and feed water temperature characteristics in the exhaust heat recovery boiler having the feed water system of the embodiment shown in FIG. The heat recovery of the exhaust gas can be efficiently performed at about 100 ° C. at the boiler outlet with respect to 600 ° C.
[0047]
In this embodiment, the high-pressure primary economizer 27a is arranged downstream of the low-pressure evaporator 21 and downstream of the intermediate-pressure primary economizer 22a in the exhaust gas passage between the intermediate-pressure evaporator 26 and the low-pressure evaporator 21. The high-pressure secondary economizer 27b is arranged downstream of the medium-pressure secondary economizer 22b. The high-pressure primary economizer 27a and the high-pressure secondary economizer 27b are respectively arranged at the medium-pressure primary economizer 22a and the medium-pressure economizer. Since there is no problem in the heat recovery of the exhaust gas even if it is arranged upstream or in parallel with the secondary economizer 22b, the same effect can be obtained.
[0048]
Next, in the embodiment shown in FIG. 3, the intermediate pressure primary economizer 22 a, the low pressure evaporator 21, the high pressure primary economizer 27 a, and the intermediate pressure two in order from the downstream side to the upstream side of the exhaust gas flow path of the exhaust heat recovery boiler. A next economizer 22b, a high-pressure secondary economizer 27b, an intermediate-pressure evaporator 26, a high-pressure tertiary economizer 27c, and a high-pressure evaporator 31 are arranged.
[0049]
A low-pressure feed pump 9 is installed on the feed water inlet side to the exhaust heat recovery boiler, and an outlet feed pipe 10 from the low-pressure feed pump 9 is directly connected to the inlet of the high-pressure feed pump 16. Water is supplied to the high-pressure drum 30 by the high-pressure tertiary economizer 27c through the vessel 27a and the high-pressure secondary economizer 27b sequentially.
[0050]
Further, water is supplied from the intermediate stage of the high-pressure feed pump 16 to the intermediate-pressure drum 25 through the intermediate-pressure primary economizer 22a and the intermediate-pressure secondary economizer 22b sequentially.
[0051]
The feed water at about 50 ° C. from the high pressure feed water pump 16 is heated to about 120 ° C. by heat recovery at the high pressure primary economizer 27a and then rises to about 210 ° C. by heat recovery at the high pressure secondary economizer 27b. Then, the temperature is raised to about 310 ° C. by heat recovery in the high pressure tertiary economizer 27 c and supplied to the high pressure drum 30. Therefore, the exhaust gas temperature does not extremely decrease due to excessive heat recovery in the high-pressure economizer as in the conventional example, and heat recovery is performed without difficulty in each of the economizers 27a to 27c.
[0052]
In addition, about 50 ° C. feed water from the intermediate stage of the high pressure feed water pump 16 is heated to about 150 ° C. by heat recovery at the intermediate pressure primary economizer 22a, and then recovered at the intermediate pressure secondary economizer 22b. The temperature is raised to about 220 ° C. and water is supplied to the intermediate pressure drum 25. Here, since the saturation temperature of the medium pressure evaporator 26 is about 230 ° C., the difference from the feed water temperature can be reduced to about 10 ° C., and the generation of thermal stress is prevented.
[0053]
Although the exhaust gas temperature and the steam and feed water temperature characteristics in the exhaust heat recovery boiler having the feed water system of the embodiment shown in FIG. 3 of the present invention are not shown, the exhaust gas of about 600 ° C. at the boiler inlet is about 100 ° C. at the boiler outlet. become.
[0054]
Next, in the embodiment shown in FIG. 4, the low-pressure economizer 11, the low-pressure evaporator 21, the high-pressure primary economizer 27a, and the medium-pressure primary economizer in order from the downstream side to the upstream side of the exhaust gas flow path of the exhaust heat recovery boiler. A vessel 22a, a high pressure secondary economizer 27b, an intermediate pressure secondary economizer 22b, an intermediate pressure evaporator 26, a high pressure tertiary economizer 27c, and a high pressure evaporator 31 are arranged.
[0055]
The outlet water supply pipe 10 from the low-pressure feed pump 9 on the feed water inlet side to the exhaust heat recovery boiler is directly connected to the inlet of the high-pressure feed pump 16, branches from the upstream side of the high-pressure feed pump 16, and passes through the low-pressure economizer 11. The low pressure drum 14 is supplied with water. Further, water is supplied to the high-pressure drum 30 through the high-pressure primary economizer 27a and the high-pressure secondary economizer 27b sequentially by the high-pressure feed water pump 16, and further via the high-pressure tertiary economizer 27c.
[0056]
Further, water is supplied to the intermediate pressure drum 25 from the intermediate stage of the high pressure feed pump 16 through the intermediate pressure primary economizer 22a and the intermediate pressure secondary economizer 22b in sequence.
[0057]
In addition, the recirculation pipe 18 is branched from the feed water pipe 23b that connects the intermediate pressure primary economizer 22a and the intermediate pressure secondary economizer 22b, and is returned to the feed water pipe 10 at the inlet of the high-pressure feed pump 16. The connection part of the recirculation pipe 18 to the water supply pipe 10 is upstream of the branch part of the water supply pipe 20 to the low pressure economizer 11 branched from the water supply pipe 10. And the feed water from the recirculation piping 18 makes the temperature of the feed water from the low-pressure feed pump 9 about 50 degreeC, and prevents the low temperature corrosion of each economizer.
[0058]
The feed water at about 50 ° C. from the high pressure feed water pump 16 is heated to about 120 ° C. by heat recovery at the high pressure primary economizer 27a and then rises to about 210 ° C. by heat recovery at the high pressure secondary economizer 27b. Then, the temperature is raised to about 310 ° C. by heat recovery in the high pressure tertiary economizer 27 c and supplied to the high pressure drum 30. Therefore, the exhaust gas temperature does not extremely decrease due to excessive heat recovery in the high-pressure economizer as in the conventional example, and heat recovery is performed efficiently and efficiently in each economizer.
[0059]
In addition, about 50 ° C. feed water from the intermediate stage of the high pressure feed water pump 16 is heated to about 150 ° C. by heat recovery at the intermediate pressure primary economizer 22a, and then recovered at the intermediate pressure secondary economizer 22b. The temperature is raised to about 220 ° C. and water is supplied to the intermediate pressure drum 25. Here, since the saturation temperature of the intermediate pressure evaporator 26 is about 230 ° C., the difference from the feed water temperature can be reduced to about 10 ° C., and the generation of thermal stress is prevented.
[0060]
The high pressure economizer 27 and the medium pressure economizer 22 arranged in the exhaust gas flow path between the intermediate pressure evaporator 26 and the low pressure evaporator 21 may be arranged in parallel with each other even if the arrangement in the exhaust gas flow path is mutually replaced. Even if there is no problem in the heat recovery of the exhaust gas, the same effect can be obtained.
[0061]
【The invention's effect】
According to the present invention, water supply to the high-pressure drum is performed via the high-pressure economizer arranged in two or more places in the gas flow path, and water supply to the intermediate pressure drum is performed in the gas flow path 2. Since it is conducted via medium pressure economizers that are divided into more than one location, heat recovery of exhaust gas can be performed efficiently, plant performance can be improved, and excessive thermal stress is generated in the drum. It is possible to provide a waste heat recovery boiler having a water supply system and a water supply device that can prevent the above.
[Brief description of the drawings]
FIG. 1 is a view showing a water supply system of an exhaust heat recovery boiler according to an embodiment of the present invention.
FIG. 2 is a view showing a water supply system of an exhaust heat recovery boiler according to an embodiment of the present invention.
FIG. 3 is a diagram showing a water supply system of an exhaust heat recovery boiler according to an embodiment of the present invention.
FIG. 4 is a view showing a water supply system of an exhaust heat recovery boiler according to an embodiment of the present invention.
FIG. 5 is a diagram showing exhaust gas temperature and steam and feed water temperature characteristics in an exhaust heat recovery boiler having a feed water system according to an embodiment of the present invention.
FIG. 6 is a diagram showing exhaust gas temperature, steam and feed water temperature characteristics in an exhaust heat recovery boiler having a feed water system according to an embodiment of the present invention.
FIG. 7 is a diagram showing a schematic system of a combined power plant having an exhaust heat recovery boiler.
FIG. 8 is a view showing a water supply system of a conventional heat recovery steam generator.
FIG. 9 is a view showing a water supply system of a conventional heat recovery steam generator.
FIG. 10 is a diagram showing exhaust gas temperature and steam and feed water temperature characteristics in an exhaust heat recovery boiler having a conventional feed water system.
[Explanation of symbols]
9 Low pressure water supply pump 10 Water supply piping
11 Low pressure economizer 14 Low pressure drum
16 High pressure feed pump 18 Recirculation piping
19 Recirculation control valve 21 Low pressure evaporator
22 Medium pressure economizer 25 Medium pressure drum
26 Medium pressure evaporator 27 High pressure economizer
30 High pressure drum 31 High pressure evaporator

Claims

ガスタービンからの排ガス流路に設けられ、復水器からの復水を低圧と高圧の給水ポンプにより低圧、中圧及び高圧レベルの三重圧または中圧と高圧の二重圧などの複圧に昇圧し、各圧力レベルの節炭器を経て各圧力レベルのドラムに給水する給水系と、各圧力レベルの蒸発器の伝熱管群において排ガスの熱を回収して蒸気を発生させると共に、発生した蒸気を各圧力レベルのドラムからそれぞれの圧力レベルの過熱器を経て蒸気タービンへ供給する蒸気系とから構成され、少なくとも節炭器の低温腐食を防止するため、節炭器で熱回収した高温の給水の一部を再循環配管により高圧の給水ポンプ入口の上流側の給水配管に戻す、給水の再循環系を有する排熱回収ボイラにおいて、
高圧給水ポンプからの高圧ドラムへの給水を排ガス流路の２か所以上に分割して配置した高圧節炭器により行うと共に、高圧給水ポンプからの中圧ドラムへの給水を排ガス流路の２か所以上に分割して配置した中圧節炭器により行うことを特徴とする排熱回収ボイラ。It is provided in the exhaust gas flow path from the gas turbine, and the condensate from the condenser is boosted to low pressure, medium pressure and high pressure triple pressure or double pressure such as medium pressure and high pressure by a low and high pressure feed pump. In the water supply system for supplying water to the drums at each pressure level through the economizers at each pressure level and the heat transfer tube group of the evaporator at each pressure level, the heat of the exhaust gas is recovered and steam is generated. High-temperature feed water that is recovered by heat from the economizer in order to prevent low-temperature corrosion of the economizer, at least in order to prevent low-temperature corrosion of the economizer In a waste heat recovery boiler having a water recirculation system that returns a part of the water to the water supply pipe upstream of the high-pressure feed water pump inlet by recirculation pipe,
Water is supplied from the high-pressure feed pump to the high-pressure drum using a high-pressure economizer that is divided into two or more locations in the exhaust gas flow path, and water from the high-pressure feed pump to the intermediate pressure drum is supplied to the exhaust gas flow path 2 An exhaust heat recovery boiler, which is performed by a medium-pressure economizer divided into more than one place.

高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第一の高圧節炭器を経て、さらに高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第二の高圧節炭器により行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の中圧節炭器を経由して行うことを特徴とする請求項１に記載の排熱回収ボイラ。The feed water to the high-pressure drum passes through the first high-pressure economizer arranged in the exhaust gas flow path between the medium-pressure evaporator and the low-pressure evaporator from the high-pressure feed pump, and further, the exhaust gas between the high-pressure evaporator and the medium-pressure evaporator The first medium-pressure economizer is arranged in the exhaust gas channel downstream of the low-pressure evaporator from the intermediate stage of the high-pressure feedwater pump with the second high-pressure economizer arranged in the flow path. 2. The exhaust heat recovery boiler according to claim 1, wherein the exhaust heat recovery boiler is disposed via a second intermediate pressure economizer disposed in an exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator.

高圧ドラムへの給水を高圧給水ポンプから低圧蒸発器の下流の排ガス流路に配置した第一の高圧節炭器と、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の高圧節炭器を順次経て、さらに高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した第二の中圧節炭器を経由して行うことを特徴とする請求項１に記載の排熱回収ボイラ。The first high-pressure economizer is disposed in the exhaust gas flow path downstream of the low-pressure evaporator from the high-pressure feed water pump, and the second is disposed in the exhaust gas flow path between the intermediate-pressure evaporator and the low-pressure evaporator. Through the high-pressure economizer in turn, and further through the third high-pressure economizer arranged in the exhaust gas flow path between the high-pressure evaporator and the intermediate-pressure evaporator, From the middle stage of the pump, through the first medium pressure economizer located in the exhaust gas flow path downstream of the low pressure evaporator, the second medium pressure located in the exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator It performs via a economizer, The exhaust heat recovery boiler of Claim 1 characterized by the above-mentioned.

高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に第二の中圧節炭器を挟んで分割して配置した第一の高圧節炭器と第二の高圧節炭器を順次経て、高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から低圧蒸発器の下流の排ガス流路に配置した第一の中圧節炭器を経て、中圧蒸発器と低圧蒸発器の間の排ガス流路に配置した前記第二の中圧節炭器を経由して行うことを特徴とする請求項１に記載の排熱回収ボイラ。The first high-pressure economizer and the second high-pressure drum are arranged by dividing the water supply from the high-pressure drum into the exhaust gas flow path between the medium-pressure evaporator and the low-pressure evaporator with the second medium-pressure economizer interposed The two high-pressure economizers are sequentially passed through a third high-pressure economizer disposed in the exhaust gas flow path between the high-pressure evaporator and the medium-pressure evaporator, and the medium-pressure drum is supplied with high-pressure water. From the intermediate stage of the pump, through the first medium pressure economizer located in the exhaust gas flow path downstream of the low pressure evaporator, the second medium located in the exhaust gas flow path between the intermediate pressure evaporator and the low pressure evaporator. The exhaust heat recovery boiler according to claim 1, wherein the exhaust heat recovery boiler is performed via a pressure-saving charcoal unit.

高圧ドラムへの給水を高圧給水ポンプから中圧蒸発器と低圧蒸発器の間の排ガス流路に第一の中圧節炭器を挟んで分割して配置した第一の高圧節炭器と第二の高圧節炭器を順次経て、高圧蒸発器と中圧蒸発器の間の排ガス流路に配置した第三の高圧節炭器を経由して行うと共に、中圧ドラムへの給水を高圧給水ポンプの中間段から中圧蒸発器と低圧蒸発器の間の排ガス流路に前記第二の高圧節炭器を挟んで分割して配置した前記第一の中圧節炭器と第二の中圧節炭器を順次経由して行うことを特徴とする請求項１に記載の排熱回収ボイラ。The first high-pressure economizer and the first high-pressure economizer, which are arranged by dividing the feedwater to the high-pressure drum from the high-pressure feed pump into the exhaust gas flow path between the medium-pressure evaporator and the low-pressure evaporator with the first medium-pressure economizer interposed The two high-pressure economizers are sequentially passed through a third high-pressure economizer arranged in the exhaust gas flow path between the high-pressure evaporator and the medium-pressure evaporator, and the water supply to the intermediate-pressure drum is supplied to the high-pressure water supply. The first medium-pressure economizer and the second medium-scale economizer, which are arranged separately from the intermediate stage of the pump in the exhaust gas flow path between the intermediate-pressure evaporator and the low-pressure evaporator with the second high-pressure economizer interposed therebetween The exhaust heat recovery boiler according to claim 1, wherein the exhaust heat recovery boiler is performed sequentially through a pressure-saving charcoal unit.

高圧節炭器と中圧節炭器をそれぞれ二つ以上に分割し、各分割された高圧節炭器の少なくとも一つを高圧蒸発器と中圧蒸発器の間の排ガス流路に配置し、他の少なくとも一つの高圧節炭器を中圧蒸発器と低圧蒸発器の間または低圧蒸発器の下流側の排ガス流路に配置し、各分割された中圧節炭器の少なくとも一つを中圧蒸発器と低圧蒸発器の間の排ガス流路に配置し、他の少なくとも一つの中圧節炭器を低圧蒸発器の下流側の排ガス流路に配置したことを特徴とする請求項１記載の排熱回収ボイラ。Dividing the high-pressure economizer and the medium-pressure economizer into two or more, respectively, placing at least one of the divided high-pressure economizers in the exhaust gas flow path between the high-pressure evaporator and the intermediate-pressure evaporator, At least one other high-pressure economizer is placed between the medium-pressure evaporator and the low-pressure evaporator or in the exhaust gas flow path downstream of the low-pressure evaporator, and at least one of the divided medium-pressure economizers is 2. The exhaust gas flow path between the pressure evaporator and the low pressure evaporator, and at least one other medium pressure economizer is disposed in the exhaust gas flow path downstream of the low pressure evaporator. Waste heat recovery boiler.

二つに分割した中圧節炭器の少なくとも第一の中圧節炭器の出口給水を低圧ドラムと第二の中圧節炭器にそれぞれ別個に供給し、第二の中圧節炭器の出口給水を中圧ドラムに供給することを特徴とする請求項６に記載の排熱回収ボイラ。Supply the outlet water of at least the first medium pressure economizer of the medium pressure economizer divided into two separately to the low pressure drum and the second medium pressure economizer, respectively. The exhaust heat recovery boiler according to claim 6, wherein the outlet water supply is supplied to the intermediate pressure drum.

低圧蒸発器の下流側の排ガス流路に配置される高圧節炭器と中圧節炭器または中圧蒸発器と低圧蒸発器の間の排ガス流路に配置される高圧節炭器と中圧節炭器をそれぞれ排ガス流れに対して並列に配置したことを特徴とする請求項１〜７のいずれかに記載の排熱回収ボイラ。High pressure economizer and medium pressure economizer disposed in the exhaust gas flow path downstream of the low pressure evaporator or high pressure economizer and medium pressure disposed in the exhaust gas flow path between the medium pressure evaporator and the low pressure evaporator The exhaust heat recovery boiler according to any one of claims 1 to 7, wherein the economizers are arranged in parallel to the exhaust gas flow.