JP3816433B2

JP3816433B2 - Renewal method of water heater

Info

Publication number: JP3816433B2
Application number: JP2002333760A
Authority: JP
Inventors: 昌二中島; 文男小原; 正喜高橋
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-11-18
Filing date: 2002-11-18
Publication date: 2006-08-30
Anticipated expiration: 2022-11-18
Also published as: JP2004169947A

Description

【０００１】
【発明の属する技術分野】
本発明は、蒸気タービンを用いる発電プラント等において復水器で得られた凝縮水を加熱して蒸気発生器に供給する給水加熱器に関し、より詳しくは、この給水加熱器の加熱管を含む一部を新製して取り替える工事を容易にする給水加熱器の改修方法に関する。
【０００２】
【従来の技術】
従来、火力発電所や原子力発電所等においては発電機を駆動するために蒸気タービンが用いられているが、この蒸気タービンから排出された蒸気は復水器で冷却されて凝縮水となった後、給水加熱器で一旦加熱され、次いで蒸気発生器でさらに加熱されて蒸気となり蒸気タービンに戻される。なお、例えば、沸騰水型原子炉における蒸気発生器は原子炉圧力容器である。
【０００３】
次に、上述の給水加熱器の構造例を図１を参照して概説する。給水加熱器１は、復水器で得られた凝縮水を受け入れる円筒状の水室２と、水室２から導入された水を通してこの水を加熱する管束３を有する。水室２と管束３の間には管板６があって管束３内の加熱管５を固定している。管束３は、軸を水平にした円筒状の本体胴４内に配置され、この本体胴４内に蒸気タービンから抽気した高温蒸気が受け入れられて管束３で熱交換する。
【０００４】
そして、前記凝縮水は水室２の給水入口座７から導入され、入口側に設けた水室仕切板８内に導かれ、本体胴４内の管束３中のＵ字状に延在する多数の加熱管５の内部を通過する際に、本体胴内の管束部に導入された高温蒸気との熱交換によって加熱された後、水室２の給水出口座９を介して蒸気発生器に送られる。
【０００５】
なお、図１中に符号２１０は多数の加熱管５を保持するために本体胴４内に配置された支え板である。符号１１は、本体胴４の内部に生じたドレンからさらに余熱を回収するためのドレン冷却部であって、加熱管５の外面の下側からドレンを流下させて、上下方向に加熱管５の外側をジグザグに流れる流れを形成させて加熱管５内の給水と熱交換させて管板６側から流出させるものである。なお、このジグザグ流れはドレン冷却部内に設けた上部を切り欠いた支え板と下部を切り欠いた支え板を交互に設けることによって作り出している。
符号１２および１２ａは給水加熱器１の荷重を支持する脚である。脚１２は本体胴４の下部に取り付けられ、脚１２ａは水室２の側部に取り付けられている。
【０００６】
本体胴４の上部には、高温蒸気を導入するための蒸気入口座１３が設けられている。さらに、ドレン冷却部１１を出たドレンを本体胴４の外部に排出するために、図示しないドレン出口が配置されている。
【０００７】
なお、発電所等に据え付けられている既設の給水加熱器を新しい給水加熱器に取り替える工事の際には、従来、既設の給水加熱器を設置場所から外に搬出した後、製造工場でその全体を完成させた新しい給水加熱器を発電所内に搬入し、所定の設置場所に据え付けていた。また、特許文献１に記載したように各部品をバラバラに搬入し設置場所で組み立てを行なう方法も知られている。
【０００８】
【特許文献１】
特開２００１−１１６２０５号公報
【０００９】
【発明が解決しようとする課題】
ところで、給水加熱器は、その本体胴の外径が約２ｍで、蒸気入口座や給水出入口座や脚等を含めると相当外径は約３ｍとなり、全長が１０ｍを越える大きなものであるばかりでなく、その全体重量が４０トン〜１００トンもある非常に重い構造物である。これにより、新しい給水加熱器を発電所内に搬入する際には、幅が３ｍで高さが２ｍかつ長さが１０ｍを越える特別に大きな台車を使用する必要がある。
【００１０】
一方、原子力発電所の場合には、その特有な構造のため、給水加熱器の設置場所や搬入通路等がコンクリートの壁や柱で囲まれている。さらに、その内部には、系統停止に制約があったり放射性物質を内包したりする配管類や、ケーブル類、その他の設備等が縦横に設置されている。
【００１１】
したがって、新しい給水加熱器をそっくりそのまま原子力発電所内に搬入する従来の取替工事では、搬入の際に給水加熱器や台車等と干渉する建物および周囲の設備を改修したり原子力発電所の床を補強したりしなければならず、多大な費用や労力がかかるばかりでなく、取替工事（改修工事）に長い工期を必要としていた。
【００１２】
特許文献１による補修方法は従来の一体搬入方式に比べ、搬入の際に給水加熱器と干渉する建物や周囲の設備を改修する工事を不要にできるばかりでなく、既に設置されている給水加熱器の本体胴を再利用することにより新しい給水加熱器の製造に要する費用を低減でき、廃棄物も低減できた。しかし、設置場所での給水加熱器の組立て作業量がかなり多いことから、短い定期検査期間では給水加熱器の新製取替え工事ができなかった。さらに、比較的健全であった水室を廃棄物として処理していた。
【００１３】
本発明の目的は、上述した特許文献１の給水加熱器組立技術が有する課題を解消し、既設の給水加熱器の水室を再利用することにより新しい給水加熱器の製造に要する費用を低減でき、かつ短い定期検査期間で給水加熱器の新製取替工事が可能となる給水加熱器の改修方法を提供することにある。
【００１４】
【課題を解決するための手段】
上記の課題を解決するため、請求項１に記載の発明は、蒸気タービンが排出した蒸気を冷却して得られた凝縮水を加熱して蒸気発生器に供給する給水加熱器の改修方法であって、前記給水加熱器は、給水管の途中に介挿されるようにして設置され前記凝縮水を導入する給水入口座および加熱後の前記凝縮水を取り出す給水出口座を有する水室と、前記水室に対して管板を介して接続されて蒸気入口とドレン出口とを有する本体胴と、前記管板に接続されて前記本体胴内に配置された複数の加熱管と、を有して、前記給水管の上流側から前記給水入口座に導入された前記凝縮水が、前記加熱管内を通って前記給水出口座を経て前記給水管の下流側に取り出される過程で前記蒸気入口から導入された蒸気によって前記加熱管で加熱されるように構成されており、当該改修方法は、既設の前記本体胴と前記管板の間を分離する本体胴・管板分離工程と、前記本体胴・管板分離工程の後に当該既存の本体胴を仮置きする本体胴仮置き工程と、既存の前記水室の給水入口座と給水出口座とを前記給水管に接続したままの状態で、かつ当該水室を移動させることなく前記管板と前記水室とを分離する管板・水室分離工程と、新たな管板と複数の加熱管とを結合して組み立てる管板・加熱管製造工程と、前記管板・加熱管製造工程および管板・水室分離工程の後に、前記新たな複数の加熱管が結合された管板を溶接により前記水室と接合する管板・水室接合工程と、前記本体胴仮置き工程および管板・加熱管製造工程の後に、前記仮置きされた既存の本体胴を溶接により前記新たな管板と接合する本体胴・管板接合工程と、を有すること、を特徴とする。
【００１５】
また、請求項１４に記載の発明は、蒸気タービンが排出した蒸気を冷却して得られた凝縮水を加熱して蒸気発生器に供給する給水加熱器の改修方法であって、前記給水加熱器は、給水管の途中に介挿されるようにして設置され前記凝縮水を導入する給水入口座および加熱後の前記凝縮水を取り出す給水出口座を有する水室と、前記水室に対して管板を介して接続されて蒸気入口とドレン出口とを有する本体胴と、前記管板に接続されて前記本体胴内に配置された複数の加熱管と、を有して、前記給水管の上流側から前記給水入口座に導入された前記凝縮水が、前記加熱管内を通って前記給水出口座を経て前記給水管の下流側に取り出される過程で前記蒸気入口から導入された蒸気によって前記加熱管で加熱されるように構成されており、当該改修方法は、既設の前記水室の給水入口座と給水出口座とを前記給水管に接続したままの状態で、かつ当該水室を移動させることなく既存の前記管板と前記水室とを分離する管板・水室分離工程と、新たな管板と複数の加熱管と本体胴とを互いに結合して管板と加熱管と本体胴の組立体を製造する製造工程と、前記製造工程の後に前記組立体を前記既存の水室の近くに搬送する搬送工程と、前記搬送工程および管板・水室分離工程の後に、前記組立体と前記水室とを接合する接合工程と、を有すること、を特徴とする。
【００１６】
【発明の実施の形態】
以下、本発明に係る給水加熱器の改修方法の各実施の形態を、図１ないし図１２を参照して詳細に説明する。なお、以下の説明においては、同一の部分には同一の符号を用いて、重複説明は省略する。
【００１７】
［第１の実施の形態］
最初に図１、２を参照して本発明に係る給水加熱器の改修方法の第１の実施の形態を説明する。この実施の形態は、図１に示す既設の給水加熱器が原子力発電所内にあるとして、その給水加熱器の管束３および管板６を新しいものと交換する方法である。
【００１８】
まず、既設の給水加熱器の本体胴４が、管板６との溶接部で、円周方向に溶断され、引き抜かれる。これにより本体胴４は、管束３、管板６、水室２から分離され、近傍に一時保管される。さらに、水室２と管板６の溶接部から円周方向に溶断され、水室２と管板６が分離される。この場合、水室２の給水入口座７と給水出口座９は図示外の給水管に接続されたままの状態で、脚１２ａを図示外の基礎にボルトで固定されたままの状態になっている。分離された古い給水加熱器の管板６、管束３、ドレン冷却部１１はさらに分解されて設置場所から搬出される。
【００１９】
これにより、給水加熱器の取替工事に際して、大型で重い構造物である給水加熱器全体を搬出する必要がないから、原子力発電所の建物を改修したり給水加熱器の周囲の設備を除去したりする工事を不要にできる。
【００２０】
一方、工場で新しく一体に製造された管束３、ドレン冷却部１１、管板６は、直径が２メートル程度で長さが１０メートル程度となり、重量は給水加熱器全重量の約半分となる。これにより、搬入時に小型の台車を使用することができるので、原子力発電所の床を補強する工事を大幅に低減できる。また、原子力発電所の建物や給水加熱器の周囲の設備との干渉を大幅に減少させることができるから、原子力発電所の建物を改修したり給水加熱器の周囲の設備を除去したりする工事を不要にできる。
【００２１】
なお、特許文献１には、短胴付水室の長さを６メートル以内にすると、大幅に干渉物減らすことができる旨記載されている。水室の外径は約２メートルであるが、水室に給水入口座、給水出口座、脚等が取り付けられており、これらを含めた実際の相当外径は約３メートルとなる。したがって、本実施の形態により真実外径（実際の外径）を例えば約２メートルに縮小できると、管束と管板の長さを約１０メートルに長くしても、設置場所への搬送・搬入における困難性は、同程度または軽減される。
【００２２】
新しく一体製造した管束３、ドレン冷却部１１、管板６は、所定の設置場所への搬入が完了すると、設置場所において水室２に溶接で取り付けられる。次いで、一時保管していた本体胴４を開先加工して、管束３およびドレン冷却部１１に被せて管板に溶接で取り付けることにより、新しい給水加熱器１０の組み立てを完了する。
【００２３】
第１の実施の形態の給水加熱器の改修方法によれば、大型で重い給水加熱器の全体を設置場所から搬出したり搬入したりする必要がないから、給水加熱器の搬出および搬入の際に給水加熱器と干渉する建物や周囲の設備を改修する工事が不要または最小限とすることができる。しかも、通常発生する水室に接続している厚肉給水管の撤去復旧工事も無くすことができるので、設置場所での給水加熱器の組立作業量も大幅に低減でき、給水加熱器の取替工事（改修工事）に要する工期を大幅に短縮し、かつ取替工事に要する費用を大幅に低減することができる。
【００２４】
また、既に設置されている給水加熱器の本体胴と水室を再利用するので、新しい給水加熱器の製造に要する資材や労力等を大幅に節約することができる。さらに、取替工事に伴って生じる廃棄物の量を大幅に減少させることができる。
【００２５】
特に原子力発電所の内部には、系統停止に制約があったり放射性物質を内包したりする配管類やケーブル類、その他の設備等が縦横に設置されているため、これらの設備の改修を不要とすることにより、給水加熱器の取替工事に伴う費用を低減し、かつ工事に伴って生じる廃棄物の量を減少させることができる。
【００２６】
上記実施の形態において、古い給水加熱器の管板６、管束３等を水室２から分離した後に現場から撤去するに当たっては、管束３の外側に搬出用仮胴（図示せず）を被せるとよい。特に原子力発電所で使用された機器については、放射線防護の観点から、搬出用仮胴の使用が望ましい。
【００２７】
また、新しい管板６、管束３等を工場で製造した時に、管板６の外側に搬入用仮胴（図示せず）を被せるとよい。搬入用仮胴は、工場での漏洩試験に使用することもでき、また、搬送時に管束３等を保護する機能も有する。
【００２８】
［第２の実施の形態］
次に、図３を参照して本発明に係る給水加熱器の改修方法の第２の実施の形態について説明する。第２の実施の形態の補修方法は、本体胴４の端部４ａに、予め炭素鋼の短胴２１を予め溶接しておく点で、上述した第１の実施の形態の補修方法と異なっている。
【００２９】
すなわち、本体胴４をクロムモリブデン鋼のような合金鋼から製造する場合には、管板６と一体に溶接する際に溶接後の後熱処理が必要となるが、この溶接部において後熱処理を行なうと、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部も後熱処理されて、溶接部が鋭敏化して応力腐食割れの原因になる。
【００３０】
そこで、第２の実施の形態の補修方法においては、図３に示すように、本体胴４の端部４ａに、本体胴４と同一外径同一肉厚で軸線方向長さが極めて短い炭素鋼製の短胴２１を溶接部２２で突合わせ溶接する。
【００３１】
その後、炭素鋼製の短胴２１と管板６を溶接部２３で溶接することにより、炭素鋼同士の溶接となるので溶接の後熱処理をほとんど不要にでき、新しい給水加熱器２０をより一層効率良く組み立てることができる。
【００３２】
［第３の実施の形態］
次に、図４を参照して本発明に係る給水加熱器の改修方法の第３の実施の形態について説明する。第３の実施の形態の補修方法は、一体に溶接する本体胴４の端部４ａに、予め炭素鋼の肉盛溶接３１を施工しておく点で、上述した第１および２の実施の形態の補修方法と異なっている。
【００３３】
すなわち、本体胴４をクロムモリブデン鋼のような合金鋼から製造する場合には、管板６と一体に溶接する際に溶接後の後熱処理が必要となるが、この溶接部において後熱処理を行なうと、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部も後熱処理されて、溶接部が鋭敏化して応力腐食割れの原因になる。
そこで、第３の実施の形態の補修方法においては、図４に示すように、本体胴４の端部４ａに、予め炭素鋼の肉盛溶接３１施工しておく。
【００３４】
その後、炭素鋼製の肉盛溶接部３１と管板６を溶接部３２で溶接することにより、炭素鋼同士の溶接となるので溶接の後熱処理をほとんど不要にでき、新しい給水加熱器３０をより一層効率良く組み立てることができる。
【００３５】
［第４の実施の形態］
次に、図５を参照して本発明に係る給水加熱器の改修方法の第４の実施の形態について説明する。第４の実施の形態の補修方法は、管板６の水室２に対向する側に、炭素鋼製の短胴４１を予め溶接しておく点で、上述した第１の実施の形態の補修方法と異なっている。
【００３６】
すなわち、管板６と水室２の溶接部は通常の厚さであれば炭素鋼同士の溶接であっても後熱処理を必要となるが、この溶接部が加熱管５と管板６の溶接部に近い場合、後熱処理を行なうと、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部も後熱処理されて、溶接部が鋭敏化して応力腐食割れの原因になる。
【００３７】
そこで、第４の実施の形態の補修方法においては、図５（ｂ）に示すように、管板６の水室２に対向する側の端部６ａに、短胴４１を工場で、加熱管５を管板６に溶接する前に予め溶接して、後熱処理も施工しておく。短胴４１は筒状であって、好ましくは、水室２と同一外径同一肉厚で、軸線方向長さＬ４は水室胴板厚Ｔａの例えば３倍以上である。
【００３８】
その後、設置場所で、図５（ａ）に示すように、管板の短胴４１と水室２を突合わせ溶接すれば、後熱処理部から加熱管５と管板６の溶接部までに距離があるので、当該部の温度は鋭敏化を起こす温度まで上昇しない。その結果、ステンレス鋼製加熱管５と管板６の溶接部の鋭敏化による応力腐食割れを防止できる。
【００３９】
［第５の実施の形態］
次に、図６を参照して本発明に係る給水加熱器の改修方法の第５の実施の形態について説明する。第５の実施の形態の補修方法は、管板６の水室側に予め設ける短胴６ｂを管板製作時に鍛造品で一体加工しておく点で、上述した第１および第４の実施の形態の補修方法と異なっている。
【００４０】
すなわち、管板６と水室２の溶接部は通常の厚さであれば炭素鋼同士の溶接であっても後熱処理を必要となるが、この溶接部が加熱管５と管板６の溶接部に近い場合、後熱処理を行なうと、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部も後熱処理されて、溶接部が鋭敏化して応力腐食割れの原因になる。
【００４１】
そこで、第５の実施の形態の補修方法においては、図６（ｂ）に示すように、管板の水室側に、短胴６ｂを管板製造時に鍛造品で一体製造しておく。短胴６ｂは筒状であって、好ましくは、水室２と同一外径同一肉厚で、軸線方向長さＬ５は水室胴板厚Ｔａの例えば３倍以上である。
【００４２】
その後、設置場所で図６（ａ）に示すように、管板６の短胴６ｂと水室２を突合わせ溶接すれば、後熱処理部から加熱管５と管板６の溶接部までに距離があるので、当該部の温度は鋭敏化を起こす温度まで上昇しない。その結果、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部の鋭敏化による応力腐食割れを防止でき、かつ新しい給水加熱器５０をより一層効率良く安価に組み立てることができる。
【００４３】
［第６の実施の形態］
次に、図７を参照して本発明に係る給水加熱器の改修方法の第６の実施の形態について説明する。第６の実施の形態の補修方法は、管板６の本体側６ｃに、炭素鋼製の短胴６１を予め溶接しておく点で、上述した第１の実施の形態の補修方法と異なっている。
【００４４】
すなわち、管板６と本体胴４の溶接部は厚さにより炭素鋼同士の溶接であっても後熱処理が必要となるが、この溶接部が加熱管５と管板６の溶接部に近い場合、後熱処理を行なうと、ステンレス鋼製の加熱管５と炭素鋼製の管板６の溶接部も後熱処理されて、溶接部が鋭敏化して応力腐食割れの原因になる。
【００４５】
そこで、第６の実施の形態の補修方法においては、図７（ｂ）に示すように、管板の本体側端部６ｃに、短胴６１を、工場で加熱管５を管板６に溶接する前に予め溶接して、後熱処理も施工しておく。短胴６１は筒状であって、好ましくは、水室２と同一外径同一肉厚で、軸線方向長さＬ６は本体胴の板厚Ｔｂの例えば３倍以上である。
【００４６】
その後、設置場所で図７（ａ）に示すように、管板６の短胴６１と本体胴４を突合わせ溶接すれば、後熱処理部から加熱管６と管板６の溶接部までに距離があるので、当該部の温度は鋭敏化を起こす温度まで上昇しない。その結果、ステンレス鋼製の加熱管溶接部の鋭敏化による応力腐食割れを防止できる。
【００４７】
［第７の実施の形態］
次に、図８を参照して本発明に係る給水加熱器の改修方法の第７の実施の形態について説明する。第７の実施の形態の補修方法は、本体胴４が炭素鋼の場合、本体胴４の内面減肉部にステンレス鋼の肉盛り溶接７１を行なうものである。
【００４８】
すなわち、給水加熱器の本体胴４内に導入される高温蒸気には酸素ガスが含まれるため、本体胴４が炭素鋼の場合、腐食が進んで減肉しているおそれがある。そこで、本体胴４の内面に減肉があった場合は、当該部をステンレス鋼の肉盛り溶接７１で、減肉部の炭素鋼の部分を覆っておく。なお、減肉部は通常、本体胴４内で最も高温にさらされる蒸気入口座１３内面およびその付近が想定される。
【００４９】
その後、本体胴４に管束３を挿入し、管板６と溶接して給水加熱器を組み立てると、運用に入ってから本体胴４の高温蒸気に含まれる酸素ガスによって腐食して減肉し易い部分はステンレス鋼７１に覆われているので、減肉が進行しなくなり、新しい給水加熱器７０の長寿命化を図ることができる。
【００５０】
［第８の実施の形態］
次に、図９を参照して本発明に係る給水加熱器の改修方法の第８の実施の形態について説明する。第８の実施の形態の補修方法は、本体胴４が炭素鋼の場合、本体胴４の内面減肉部にステンレス鋼の当て板８１を溶接取付するものである。
【００５１】
すなわち、給水加熱器の本体胴４内に導入される高温蒸気には酸素ガスが含まれるため、本体胴４が炭素鋼の場合、腐食が進んで減肉しているおそれがある。そこで、本体胴４の内面に減肉があった場合は、当該部にステンレス鋼の当て板８１を溶接部８２で溶接して取り付け、減肉部の炭素鋼の部分を覆っておく。なお、蒸気入口座１３の開口部と当て板８１が干渉する場合は、流路を妨げないように、例えば、当て板８１に蒸気入口座１３の開口部よりもわずかに大きな開口（図示せず）を設ける。
【００５２】
その後、本体胴４に管束３を挿入し、管板６と溶接して給水加熱器を組み立てると、運用に入ってから本体胴４の高温蒸気に含まれる酸素ガスによって腐食して減肉し易い部分はステンレス鋼の当て板８１に覆われているので、減肉が進行しなくなり、新しい給水加熱器８０の長寿命化を図ることができる。
【００５３】
［第９の実施の形態］
次に、図１０を参照して本発明に係る給水加熱器の改修方法の第９の実施の形態について説明する。第９の実施の形態の補修方法は、仮胴９１に管束３およびドレン冷却部１１を挿入して、本体側に短胴６１を設けた管板６と一体で設置場所に搬入する場合、短胴６１は開先加工済みとし、仮胴９１を短胴６１に一部被せて隅肉溶接で接合する。
【００５４】
すなわち、仮胴９１は管束３、管板６を設置場所へ搬入する際に加熱管５を保護するため、また工場で管板６と加熱管５の溶接部のリークチェックをするために使用するが、仮胴９１と管板６の短胴６１との接合を突き合わせ溶接で行なった場合は、設置場所で短胴６１を切断する場合に加熱管５を損傷させる恐れがあり、また切断後に開先加工をグラインダで行なう必要があり、工期と費用を要する。
そこで、予め工場で機械加工により開先加工した管板６の短胴６１の一部に仮胴端部９１ａを被せて隅肉溶接部９２で接合しておく。
【００５５】
その後、一体化した仮胴９１、９１ａ、管束３、ドレン冷却部１１、管板６を設置場所へ搬入した後、仮胴９１を取り外す際に仮胴端部９１ａと管板６の短胴６１との隅肉溶接部９２をグラインダ等で削り取れば、加熱管５を損傷させることが無く、管板６の短胴６１は既に開先加工済みなので、本体胴４との溶接を直ちに施工でき、給水加熱器をより一層効率良く安価に組み立てることができる。
【００５６】
［第１０の実施の形態］
次に、図１１を参照して本発明に係る給水加熱器の改修方法の第１０の実施の形態について説明する。第１０の実施の形態の補修方法は、仮胴１０１に管束３およびドレン冷却部１１を挿入して、本体側に短胴６１を設けた管板６と一体で設置場所に搬入する場合、短胴６１は開先加工済みとし、仮胴１０１を管板６の短胴６１に設けた当て板６１ａに一部被せて隅肉溶接で接合する。
【００５７】
すなわち、仮胴１０１は管束３、ドレン冷却部１１、管板６を設置場所へ搬入する際に加熱管５を保護するため、また工場で管板６と加熱管５の溶接部のリークチェックをするために使用するが、仮胴１０１と管板６の短胴６１との接合を突き合わせ溶接で行なった場合は、設置場所で短胴６１を切断する場合に加熱管５を損傷させる恐れがあり、また切断後に開先加工をグラインダで行なう必要があり、工期と費用を要する。
そこで、予め工場で機械加工により開先加工した管板６の短胴６１に設けた当て板６１ａに仮胴端部１０１ａを一部被せて隅肉溶接部１０２で接合しておく。
【００５８】
その後、一体化した仮胴１０１、１０１ａ、１０１ｂ、管束３、ドレン冷却部１１、管板６を設置場所へ搬入した後、仮胴１０１を取り外す際に仮胴端部１０１ａと管板６の短胴６１の当て板６１ａとの隅肉溶接部１０２をグラインダ等で削り取れば、加熱管５を損傷させることが無く、管板６の短胴６１も損傷させることが無く、管板６の短胴６１は既に開先加工済みなので、本体胴４との溶接を直ちに施工でき、給水加熱器をより一層効率良く安価に組み立てることができる。
【００５９】
［第１１の実施の形態］
次に、図１２を参照して本発明に係る給水加熱器の改修方法の第１１の実施の形態について説明する。第１１の実施の形態の補修方法は、設置場所で管板６と水室２の溶接を行なう際に、事前に水室２の内部の構造物である水室仕切板８を溶接して組立て完成させて、水室２内に仮置きしておく。
【００６０】
すなわち、水室２内部の構造物である仕切板８を溶接して組立て完成させて、水室２内に仮置きしなかった場合は、水室２と管板６を溶接後に水室マンホール１４から水室仕切板８の部品を水室内に搬入して、水室２内の狭い場所で溶接して組立てなければならなくなり、工期と費用を要する。
そこで、予め水室仕切板８を溶接して水室仕切板組立体として完成させて、この組立体を、管板６と水室２を溶接する前に水室２内に仮置きしておく。
【００６１】
その後、水室２と管板６の溶接完了後に、水室仕切板マンホール蓋８ａを開放しておき、管板側に設けた端板６ｄと水室仕切板（組立体）８の溶接部１１１および給水入口座７からの短管７ａと水室仕切板８との溶接部１１２を内側から溶接する。これにより、新しい給水加熱器をより一層効率良く組み立てることができる。
【００６２】
なお、短管７ａは、供給入口座７から流入した給水がすべて水室仕切板８内部に導かれるように構成されたもので、下端は給水入口座７に溶接され、上端は水室仕切板８に溶接される。これにより、水室仕切板８の外側の加熱された給水と混じることが防止される。
【００６３】
また、端板６ｄは、水室仕切板８と同じ形状で半円形の短い両端開放の筒状の構造である。仮に水室仕切板８を管板６に直接溶接すると、管板面のステンレス鋼肉盛り部（加熱管５との溶接のために施工されている）と炭素鋼の溶接でかつ構造的に溶接し難くなる。そこで、炭素鋼製の端板６ｄを予め管板６に溶接しておき、次に端板６ｄと水室仕切板８を付き合わせ溶接すれば作業性も信頼性もよくなる。
【００６４】
［第１２の実施の形態］
次に、図１３を参照して本発明に係る給水加熱器の改修方法の第１２の実施の形態について説明する。この実施の形態の補修方法では、原子力発電所内の古い給水加熱器の水室２と管板６の溶接部で円周方向に溶断され、分離される。この場合、水室２の給水入口座７と給水出口座９は図示外の給水管に接続されたままの状態で、脚１２ａを図示外の基礎にボルトで固定されたままの状態になっている。分離された古い給水加熱器の管板６、管束３、ドレン冷却部１１、本体胴４はさらに分解されて設置場所から搬出される。
【００６５】
一方、工場で新しく一体に製造された管板６、管束３、ドレン冷却部１１、本体胴４は設置場所に搬入した後、水室２に溶接で取り付けることにより新しい給水加熱器１２０の組み立てを完了する。
【００６６】
すなわち、この実施形態の給水加熱器の組立方法によれば、大型で重い給水加熱器の全体を設置場所から搬出したり搬入したりする必要がないから、給水加熱器の搬出および搬入の際に給水加熱器と干渉する建物や周囲の設備を改修する工事を大幅に減らすことができ、かつ通常発する水室２に接続している厚肉給水管の撤去復旧工事も無くすことができる。その結果、設置場所での給水加熱器の組立作業量も大幅に低減でき、給水加熱器の取替工事に要する工期を大幅に短縮し、かつ取替工事に要する費用を大幅に低減することができる。
【００６７】
また、水室２を再利用するので、新しい給水加熱器の製造に要する資材や労力等を大幅に節約することができる。さらに、取替工事に伴って生じる廃棄物の量を大幅に減少させることができる。
【００６８】
［第１３の実施の形態］
次に、図１４を参照して本発明に係る給水加熱器の改修方法の第１３の実施の形態について説明する。この実施の形態の補修方法は、第１２の実施の形態の変形例であって、工場で新しく製造する本体胴４の脚１２ｃや蒸気入口座１３ｂを設置場所で、溶接して取付ける点で、第１２の実施形態と異なっている。この場合、脚１２ｃと本体胴４の間に脚当て板１２ｂを設け、当て板１２ｂのみ工場で溶接取付けしておくことも可能である。また、本体胴４の蒸気入口座１３ａ取り付け位置には、工場で開口１３を加工しておく。
【００６９】
すなわち、この実施形態の給水加熱器１３０の組立方法によれば、工場で新しく一体に製造された、管板６、管束３、ドレン冷却部１１、本体胴４の本体胴４には脚１２ｃや蒸気入口座１３ｂが取り付けられていないので、給水加熱器の搬入の際に給水加熱器と干渉する建物や周囲の設備を改修する工事が不要となり、かつ通常発する水室２に接続している厚肉給水管の撤去復旧工事も無くすことができる。その結果、設置場所での給水加熱器の組立作業量も大幅に低減でき、給水加熱器の取替工事に要する工期を大幅に短縮し、かつ取替工事に要する費用を大幅に低減することができる。
【００７０】
また、水室２を再利用するので、新しい給水加熱器の製造に要する資材や労力等を大幅に節約することができる。さらに、取替工事に伴って生じる廃棄物の量を大幅に減少させることができる。
【００７１】
以上説明した各実施の形態の特徴を適宜組み合わせることも可能である。例えば、第１〜第６の実施の形態のいずれかに、第７の実施の形態のステンレス鋼製の肉盛り溶接７１または第８の実施の形態の当て板８１を適用することができる。また、第９または第１０の実施の形態の特徴を他の実施の形態の特徴と組み合わせること、第１１の実施の形態の特徴を他の実施の形態の特徴と組み合わせることもできる。
【００７２】
【発明の効果】
以上の説明から明らかなように、本発明の給水加熱器の改修方法によれば、既設の給水加熱器の一部を再利用することにより新しい給水加熱器の製造に要する費用を低減でき、かつ短い定期検査期間で給水加熱器の新製取替工事が可能となる。
【図面の簡単な説明】
【図１】本発明に係る給水加熱器の全体構造を示す全体立断面図。
【図２】本発明に係る給水加熱器の改修方法の第１の実施の形態における給水加熱器の模式的展開立面図。
【図３】本発明に係る給水加熱器の改修方法の第２の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図４】本発明に係る給水加熱器の改修方法の第３の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図５】本発明に係る給水加熱器の改修方法の第４の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）の管板・水室接合前の状態を模式的に示す立面図。
【図６】本発明に係る給水加熱器の改修方法の第５の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）の管板・水室接合前の状態を模式的に示す立面図。
【図７】本発明に係る給水加熱器の改修方法の第６の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）の管板・水室接合前の状態を模式的に示す立面図。
【図８】本発明に係る給水加熱器の改修方法の第７の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図９】本発明に係る給水加熱器の改修方法の第８の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図１０】本発明に係る給水加熱器の改修方法の第９の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図１１】本発明に係る給水加熱器の改修方法の第１０の実施の形態を示す図であって、（ａ）は改修後の給水加熱器の全体立面図、（ｂ）は（ａ）のＢ部拡大立断面図。
【図１２】本発明に係る給水加熱器の改修方法の第１１の実施の形態を示す図であって、（ａ）は仕切板を組み立てて水室内に仮配置した状態における要部立断面図、（ｂ）は仕切板を水室内に固定した状態における要部立断面図、（ｃ）は（ｂ）のＣ部拡大立断面図。
【図１３】本発明に係る給水加熱器の改修方法の第１２の実施の形態における現地組立前の状態を模式的に示す立面図。
【図１４】本発明に係る給水加熱器の改修方法の第１３の実施の形態における現地組立前の状態を模式的に示す立面図。
【符号の説明】
１…給水加熱器、２…水室、３…管束、４…本体胴、４ａ…本体胴端部、５…加熱管、６…管板、６ａ…管板水室側端部、６ｂ…管板と一体の鍛造品短胴、６ｃ…管板本体側端部、６ｄ…端板、７…給水入口座、７ａ…短管、８…水室仕切板、８ａ…水室仕切板マンホール蓋、９…給水出口座、１０…給水加熱器、１１…ドレン冷却部、１２…脚、１２ａ…脚、１２ｂ…当て板、１２ｃ…脚、１３…蒸気入口座、１３ａ…開口、１３ｂ…蒸気入口座、１４…水室マンホール、２０…給水加熱器、２１…炭素鋼の短胴、２２…溶接部、２３…溶接部、３０…給水加熱器、３１…炭素鋼の肉盛溶接、３２…溶接部、４０…給水加熱器、４１…炭素鋼の短胴、５０…給水加熱器、６０…給水加熱器、６１…炭素鋼の短胴、６１ａ…短胴の当て板、７０…給水加熱器、７１…ステンレス鋼の肉盛り溶接、８０…給水加熱器、８１…ステンレス鋼の当て板、８２…溶接部、９１…仮胴、９１ａ…仮胴端部、９２…溶接部、１０１…仮胴、１０１ａ…仮胴端部、１０１ｂ…仮胴端部、１０２…溶接部、１１１…溶接部、１１２…溶接部、１２０…給水加熱器、１３０…給水加熱器、２１０…支え板。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a feed water heater that heats condensed water obtained by a condenser in a power plant or the like that uses a steam turbine and supplies the condensed water to a steam generator, and more particularly includes a heating pipe of the feed water heater. The present invention relates to a method for repairing a water heater that facilitates the construction of a new part for replacement.
[0002]
[Prior art]
Conventionally, steam turbines are used to drive generators at thermal power plants and nuclear power plants, but the steam discharged from the steam turbine is cooled by a condenser to become condensed water. The water is once heated by the feed water heater and then further heated by the steam generator to become steam and returned to the steam turbine. For example, the steam generator in a boiling water reactor is a reactor pressure vessel.
[0003]
Next, a structural example of the above-described feed water heater will be outlined with reference to FIG. The feed water heater 1 has a cylindrical water chamber 2 that receives the condensed water obtained by the condenser, and a tube bundle 3 that heats the water through the water introduced from the water chamber 2. There is a tube plate 6 between the water chamber 2 and the tube bundle 3 to fix the heating tube 5 in the tube bundle 3. The tube bundle 3 is disposed in a cylindrical main body cylinder 4 having a horizontal axis, and high-temperature steam extracted from the steam turbine is received in the main body cylinder 4 to exchange heat with the tube bundle 3.
[0004]
The condensed water is introduced from the water supply account 7 of the water chamber 2, guided into the water chamber partition plate 8 provided on the inlet side, and extended in a U-shape in the tube bundle 3 in the main body barrel 4. When passing through the inside of the heating pipe 5, it is heated by heat exchange with the high-temperature steam introduced into the tube bundle part in the body trunk, and then sent to the steam generator via the water supply / out account 9 of the water chamber 2. It is done.
[0005]
In FIG. 1, reference numeral 210 denotes a support plate disposed in the main body cylinder 4 in order to hold a large number of heating tubes 5. Reference numeral 11 denotes a drain cooling section for further recovering residual heat from the drain generated inside the main body cylinder 4, and drains the drain from the lower side of the outer surface of the heating pipe 5, so that the heating pipe 5 is vertically moved. A flow that flows in a zigzag manner is formed on the outside, and heat is exchanged with the water supply in the heating tube 5 so as to flow out from the tube plate 6 side. The zigzag flow is created by alternately providing a support plate with a cutout at the top and a support plate with a cutout at the bottom provided in the drain cooling section.
Reference numerals 12 and 12 a are legs that support the load of the feed water heater 1. The legs 12 are attached to the lower part of the main body trunk 4, and the legs 12 a are attached to the sides of the water chamber 2.
[0006]
In the upper part of the main body barrel 4, a steam account 13 for introducing high-temperature steam is provided. Further, a drain outlet (not shown) is disposed to discharge the drain that has exited the drain cooling unit 11 to the outside of the main body body 4.
[0007]
In addition, when replacing existing water heaters installed at power plants with new water heaters, the existing water heaters are conventionally transported from the installation location to the whole at the manufacturing plant. The new water heater was completed and was carried into the power plant and installed at the designated location. In addition, as described in Patent Document 1, a method is also known in which components are carried apart and assembled at an installation location.
[0008]
[Patent Document 1]
JP 2001-116205 A
[0009]
[Problems to be solved by the invention]
By the way, the outer diameter of the main body of the feed water heater is about 2 m, and when including a steam account, a water account, a leg, etc., the corresponding outer diameter is about 3 m, and the total length exceeds 10 m. It is a very heavy structure with an overall weight of 40 to 100 tons. Thus, when a new feed water heater is carried into the power plant, it is necessary to use a specially large cart having a width of 3 m, a height of 2 m and a length exceeding 10 m.
[0010]
On the other hand, in the case of a nuclear power plant, because of its unique structure, the installation location of the feed water heater and the carry-in passage are surrounded by concrete walls and pillars. In addition, piping, cables, and other equipment that are restricted in system shutdown or contain radioactive substances are installed vertically and horizontally.
[0011]
Therefore, in the conventional replacement work in which a new feedwater heater is carried into the nuclear power plant as it is, the building and surrounding facilities that interfere with the feedwater heater and the bogie at the time of carry-in are modified or the floor of the nuclear power plant is installed. It had to be reinforced, and not only was it costly and labor intensive, but also required a long construction period for replacement work (renovation work).
[0012]
The repair method according to Patent Document 1 not only eliminates the need to renovate buildings and surrounding facilities that interfere with the feed water heater during carry-in, but also provides a feed water heater that has already been installed. By reusing the main body, the cost of manufacturing a new feed water heater could be reduced and the waste could be reduced. However, due to the considerable amount of work for assembling the water heater at the installation site, new replacement work for the water heater could not be performed in a short period of regular inspection. Furthermore, a relatively healthy water chamber was treated as waste.
[0013]
The object of the present invention is to eliminate the above-mentioned problems of the feed water heater assembly technique of Patent Document 1, and to reduce the cost required for manufacturing a new feed water heater by reusing the water chamber of the existing feed water heater. Another object of the present invention is to provide a method for repairing a feed water heater that enables a new replacement work for the feed water heater in a short periodic inspection period.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention described in claim 1 is a method for refurbishing a feed water heater that heats condensed water obtained by cooling steam discharged from a steam turbine and supplies the condensed water to a steam generator. The feed water heater is It is installed so as to be inserted in the middle of the water supply pipe Water supply inlet for introducing the condensed water seat And water supply outlet for taking out the condensed water after heating seat A water chamber having a steam inlet and a drain outlet connected to the water chamber via a tube plate, and a plurality of heating units connected to the tube plate and disposed in the body shell And having a tube From the upstream side of the water supply pipe The water supply inlet To the seat The introduced condensed water passes through the heating pipe and the water supply outlet. To the downstream side of the water supply pipe Taken out In the process The heating pipe is configured to be heated by the steam introduced from the steam inlet, and the repair method includes a main body cylinder / tube sheet separation step of separating between the existing main body cylinder and the tube sheet, The main body trunk temporary placing step of temporarily placing the existing main body trunk after the main body trunk / tube sheet separating step, and the existing water chamber Water supply account and water supply account are connected to the water supply pipe and the water chamber A tube plate / water chamber separating step for separating the tube plate and the water chamber without moving the tube plate, a tube plate / heating tube manufacturing step for assembling a new tube plate and a plurality of heating tubes, After the tube plate / heating tube manufacturing step and the tube plate / water chamber separation step, the tube plate / water chamber joining step for joining the water plate to the water chamber by welding the new plurality of heating tubes, After the main body trunk temporary placing step and the tube plate / heated tube manufacturing step, the main body trunk / tube plate joining step for joining the existing temporarily placed main body trunk with the new tube plate by welding, Features.
[0015]
The invention as set forth in claim 14 is a method for renovating a feed water heater for heating condensed water obtained by cooling steam discharged from a steam turbine and supplying the condensed water to a steam generator, wherein the feed water heater Is It is installed so as to be inserted in the middle of the water supply pipe Water supply inlet for introducing the condensed water seat And water supply outlet for taking out the condensed water after heating seat A water chamber having a steam inlet and a drain outlet connected to the water chamber via a tube plate, and a plurality of heating units connected to the tube plate and disposed in the body shell And having a tube From the upstream side of the water supply pipe The water supply inlet To the seat The introduced condensed water passes through the heating pipe and the water supply outlet. To the downstream side of the water supply pipe Taken out In the process The heating pipe is heated by the steam introduced from the steam inlet, and the repair method is the existing water chamber. Water supply account and water supply account are connected to the water supply pipe and the water chamber A tube plate / water chamber separating step for separating the existing tube plate and the water chamber without moving the tube plate, a new tube plate, a plurality of heating tubes, and a main body body are coupled to each other. And a manufacturing process for manufacturing an assembly of the main body body, a transport process for transporting the assembly to the vicinity of the existing water chamber after the manufacturing process, and after the transport process and the tube plate / water chamber separation process, And a joining step for joining the assembly and the water chamber.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each embodiment of the repair method of the feed water heater which concerns on this invention is described in detail with reference to FIG. 1 thru | or FIG. In the following description, the same parts are denoted by the same reference numerals, and redundant description is omitted.
[0017]
[First Embodiment]
First, with reference to FIGS. 1 and 2, a first embodiment of a method for repairing a feed water heater according to the present invention will be described. This embodiment is a method in which the existing water heater shown in FIG. 1 is in a nuclear power plant and the tube bundle 3 and the tube plate 6 of the water heater are replaced with new ones.
[0018]
First, the main body cylinder 4 of the existing water heater is melted and pulled out in the circumferential direction at the welded portion with the tube sheet 6. Thereby, the main body cylinder 4 is separated from the tube bundle 3, the tube plate 6, and the water chamber 2, and is temporarily stored in the vicinity. Furthermore, the water chamber 2 and the tube sheet 6 are separated from the welded portion between the water chamber 2 and the tube sheet 6 in the circumferential direction. In this case, the water supply account 7 and the water supply account 9 of the water chamber 2 remain connected to a water supply pipe (not shown) and the legs 12a are fixed to the foundation (not shown) with bolts. Yes. The separated tube plate 6, tube bundle 3 and drain cooling unit 11 of the old feed water heater are further disassembled and carried out of the installation location.
[0019]
As a result, there is no need to carry out the entire large and heavy feedwater heater when replacing the feedwater heater.Therefore, the building of the nuclear power plant has been renovated and the equipment around the feedwater heater has been removed. Can be eliminated.
[0020]
On the other hand, the tube bundle 3, the drain cooling unit 11, and the tube sheet 6 newly manufactured integrally at the factory have a diameter of about 2 meters and a length of about 10 meters, and the weight is about half of the total weight of the feed water heater. Thereby, since a small trolley | bogie can be used at the time of carrying in, the construction which reinforces the floor of a nuclear power plant can be reduced significantly. In addition, because interference with the facilities around the nuclear power plant and the feed water heater can be greatly reduced, the construction of repairing the nuclear power plant building and removing the facilities around the feed water heater Can be eliminated.
[0021]
Note that Patent Document 1 describes that when the length of the short-chambered water chamber is within 6 meters, it is possible to significantly reduce interference. The outer diameter of the water chamber is about 2 meters, but a water supply account, water supply account, legs, etc. are attached to the water chamber, and the actual equivalent outer diameter including these is about 3 meters. Therefore, if the true outer diameter (actual outer diameter) can be reduced to, for example, about 2 meters according to the present embodiment, even if the length of the tube bundle and the tube sheet is increased to about 10 meters, it can be transported and carried into the installation location. The difficulty in is comparable or reduced.
[0022]
The newly-manufactured tube bundle 3, the drain cooling unit 11, and the tube plate 6 are attached to the water chamber 2 by welding at the installation location when the carry-in to the predetermined installation location is completed. Next, the main body cylinder 4 that has been temporarily stored is subjected to groove processing, and the tube bundle 3 and the drain cooling unit 11 are attached to the tube plate by welding, thereby completing the assembly of the new feed water heater 10.
[0023]
According to the repair method of the feed water heater of the first embodiment, since it is not necessary to carry out and carry in the entire large and heavy feed water heater from the installation location, when carrying out and carrying in the feed water heater In addition, it is possible to eliminate or minimize the work of repairing buildings and surrounding facilities that interfere with the water heater. In addition, the removal and restoration work for the thick-walled water pipe connected to the normal water chamber can be eliminated, so the amount of assembly work for the water heater at the installation location can be greatly reduced and the water heater can be replaced. The construction period required for the construction (renovation work) can be greatly shortened, and the cost required for the replacement work can be significantly reduced.
[0024]
In addition, since the main body and the water chamber of the water heater already installed are reused, materials and labor required for manufacturing a new water heater can be greatly saved. In addition, the amount of waste generated by the replacement work can be greatly reduced.
[0025]
In particular, the nuclear power plant has piping, cables, and other equipment that are restricted in terms of system shutdown and contain radioactive materials, and are installed vertically and horizontally. By doing so, it is possible to reduce the cost associated with the replacement work of the feed water heater and to reduce the amount of waste generated with the work.
[0026]
In the above embodiment, when removing the tube plate 6, the tube bundle 3 and the like of the old feed water heater from the water chamber 2 and then removing them from the site, a temporary carrying cylinder (not shown) is put on the outside of the tube bundle 3. Good. In particular, for equipment used in nuclear power plants, it is desirable to use a temporary carrying cylinder from the viewpoint of radiation protection.
[0027]
Further, when a new tube sheet 6, tube bundle 3, etc. are manufactured at the factory, it is preferable to cover a temporary provisional cylinder (not shown) on the outside of the tube sheet 6. The temporary carrying cylinder can be used for a leak test in a factory, and has a function of protecting the tube bundle 3 and the like during transportation.
[0028]
[Second Embodiment]
Next, with reference to FIG. 3, 2nd Embodiment of the repair method of the feed water heater which concerns on this invention is described. The repair method of the second embodiment is different from the repair method of the first embodiment described above in that a carbon steel short cylinder 21 is previously welded to the end 4a of the main body cylinder 4. Yes.
[0029]
That is, when the main body cylinder 4 is manufactured from an alloy steel such as chrome molybdenum steel, post-heat treatment after welding is required when welding the tube body 6 integrally. Then, the welded portion of the stainless steel heating tube 5 and the carbon steel tubesheet 6 is also post-heat treated, and the welded portion becomes sensitized and causes stress corrosion cracking.
[0030]
Therefore, in the repair method of the second embodiment, as shown in FIG. 3, carbon steel having the same outer diameter and the same wall thickness as the main body cylinder 4 and an extremely short axial length is provided at the end 4 a of the main body cylinder 4. The short drum 21 made of butt is welded at the welding portion 22.
[0031]
Thereafter, by welding the carbon steel short body 21 and the tube plate 6 with the welded portion 23, the carbon steel is welded to each other, so that post-welding heat treatment can be made almost unnecessary, and the new feed water heater 20 is made more efficient. It can be assembled well.
[0032]
[Third Embodiment]
Next, with reference to FIG. 4, 3rd Embodiment of the repair method of the feed water heater which concerns on this invention is described. The repair method of the third embodiment is the first and second embodiments described above in that the build-up welding 31 of carbon steel is preliminarily applied to the end 4a of the main body cylinder 4 to be integrally welded. The repair method is different.
[0033]
That is, when the main body cylinder 4 is manufactured from an alloy steel such as chrome molybdenum steel, post-heat treatment after welding is required when welding the tube body 6 integrally. Then, the welded portion of the stainless steel heating tube 5 and the carbon steel tubesheet 6 is also post-heat treated, and the welded portion becomes sensitized and causes stress corrosion cracking.
Therefore, in the repair method of the third embodiment, as shown in FIG. 4, build-up welding 31 of carbon steel is performed in advance on the end 4 a of the main body barrel 4.
[0034]
After that, welding the carbon steel overlay weld 31 and the tube sheet 6 with the welded portion 32 results in welding between the carbon steels, so post-weld heat treatment can be made almost unnecessary, and a new water heater 30 can be used. It can be assembled more efficiently.
[0035]
[Fourth Embodiment]
Next, with reference to FIG. 5, 4th Embodiment of the repair method of the feed water heater which concerns on this invention is described. The repair method of the fourth embodiment is the repair of the first embodiment described above in that a carbon steel short cylinder 41 is pre-welded to the side of the tube plate 6 facing the water chamber 2. It is different from the method.
[0036]
That is, if the welded portion of the tube plate 6 and the water chamber 2 is of a normal thickness, post-heat treatment is required even if the carbon steel is welded, but this welded portion is welded between the heated tube 5 and the tube plate 6. When the heat treatment is performed in the vicinity, the welded portion of the stainless steel heating tube 5 and the carbon steel tube sheet 6 is also heat treated, and the welded portion becomes sensitized and causes stress corrosion cracking.
[0037]
Therefore, in the repair method of the fourth embodiment, as shown in FIG. 5 (b), the short cylinder 41 is installed at the end 6a on the side of the tube plate 6 facing the water chamber 2, at the factory, and the heating tube Before welding 5 to the tube sheet 6, it is welded in advance and post-heat treatment is also performed. The short body 41 is cylindrical, and preferably has the same outer diameter and the same thickness as the water chamber 2, and the axial length L4 is, for example, three times or more the water chamber body plate thickness Ta.
[0038]
Thereafter, as shown in FIG. 5 (a), if the tube plate short body 41 and the water chamber 2 are butt welded at the installation location, the distance from the post-heat treatment portion to the welded portion of the heating tube 5 and the tube plate 6 is reached. Therefore, the temperature of the part does not rise to a temperature causing sensitization. As a result, stress corrosion cracking due to sensitization of the welded portion between the stainless steel heating tube 5 and the tube sheet 6 can be prevented.
[0039]
[Fifth Embodiment]
Next, with reference to FIG. 6, 5th Embodiment of the repair method of the feed water heater which concerns on this invention is described. The repair method of the fifth embodiment is the same as that of the first and fourth embodiments described above in that the short cylinder 6b provided in advance on the water chamber side of the tube sheet 6 is integrally processed with a forged product when the tube sheet is manufactured. It is different from the form repair method.
[0040]
That is, if the welded portion of the tube plate 6 and the water chamber 2 is of a normal thickness, post-heat treatment is required even if the carbon steel is welded, but this welded portion is welded between the heated tube 5 and the tube plate 6. When the heat treatment is performed in the vicinity, the welded portion of the stainless steel heating tube 5 and the carbon steel tube sheet 6 is also heat treated, and the welded portion becomes sensitized and causes stress corrosion cracking.
[0041]
Therefore, in the repair method of the fifth embodiment, as shown in FIG. 6 (b), the short cylinder 6b is integrally manufactured with a forged product at the time of manufacturing the tube sheet on the water chamber side of the tube sheet. The short body 6b has a cylindrical shape, and preferably has the same outer diameter and the same thickness as the water chamber 2, and the axial length L5 is, for example, three times or more the water chamber body plate thickness Ta.
[0042]
Thereafter, as shown in FIG. 6A, if the short barrel 6b of the tube plate 6 and the water chamber 2 are butt welded at the installation location, the distance from the post-heat treatment portion to the welded portion of the heating tube 5 and the tube plate 6 Therefore, the temperature of the part does not rise to a temperature causing sensitization. As a result, stress corrosion cracking due to the sensitization of the welded portion of the stainless steel heating tube 5 and the carbon steel tube sheet 6 can be prevented, and a new feed water heater 50 can be assembled more efficiently and inexpensively.
[0043]
[Sixth Embodiment]
Next, with reference to FIG. 7, 6th Embodiment of the repair method of the feed water heater which concerns on this invention is described. The repair method of the sixth embodiment is different from the repair method of the first embodiment described above in that a carbon steel short cylinder 61 is welded in advance to the main body side 6c of the tube sheet 6. Yes.
[0044]
That is, even if the welded portion between the tube plate 6 and the main body body 4 is welded between carbon steels depending on the thickness, post-heat treatment is required, but this welded portion is close to the welded portion between the heated tube 5 and the tube plate 6. When the post-heat treatment is performed, the welded portion of the stainless steel heating tube 5 and the carbon steel tube sheet 6 is also post-heat treated, and the welded portion is sensitized to cause stress corrosion cracking.
[0045]
Therefore, in the repair method of the sixth embodiment, as shown in FIG. 7B, the short barrel 61 is welded to the body side end 6c of the tube plate, and the heating tube 5 is welded to the tube plate 6 at the factory. Before the heat treatment, it is pre-welded and post-heat treatment is performed. The short drum 61 is cylindrical, and preferably has the same outer diameter and the same thickness as the water chamber 2, and the axial length L6 is, for example, three times or more the plate thickness Tb of the main body drum.
[0046]
Thereafter, as shown in FIG. 7A, if the short drum 61 of the tube plate 6 and the main body drum 4 are butt welded at the installation location, the distance from the post-heat treatment portion to the welded portion of the heating tube 6 and the tube plate 6 is reached. Therefore, the temperature of the part does not rise to a temperature causing sensitization. As a result, it is possible to prevent stress corrosion cracking due to sensitization of a stainless steel heating pipe weld.
[0047]
[Seventh Embodiment]
Next, a seventh embodiment of the feed water heater refurbishing method according to the present invention will be described with reference to FIG. In the repair method of the seventh embodiment, when the main body cylinder 4 is made of carbon steel, the build-up welding 71 of stainless steel is performed on the inner surface reduced portion of the main body cylinder 4.
[0048]
That is, since the high-temperature steam introduced into the main body cylinder 4 of the feed water heater contains oxygen gas, when the main body cylinder 4 is made of carbon steel, there is a possibility that corrosion has progressed and the thickness has been reduced. Therefore, when the thickness of the inner surface of the main body barrel 4 is reduced, the portion is covered with a stainless steel build-up weld 71 to cover the carbon steel portion of the reduced thickness portion. In addition, the thinned portion is usually assumed to be the inner surface of the steam-filled account 13 that is exposed to the highest temperature in the main body trunk 4 and the vicinity thereof.
[0049]
After that, when the tube bundle 3 is inserted into the main body cylinder 4 and welded to the tube plate 6 to assemble the feed water heater, it is easily corroded by oxygen gas contained in the high temperature steam of the main body cylinder 4 after entering operation. Since the portion is covered with the stainless steel 71, the thinning does not proceed and the life of the new feed water heater 70 can be extended.
[0050]
[Eighth Embodiment]
Next, with reference to FIG. 9, 8th Embodiment of the repair method of the feed water heater which concerns on this invention is described. In the repair method of the eighth embodiment, when the main body cylinder 4 is made of carbon steel, a stainless steel backing plate 81 is welded to the inner wall thinned portion of the main body cylinder 4.
[0051]
That is, since the high-temperature steam introduced into the main body cylinder 4 of the feed water heater contains oxygen gas, when the main body cylinder 4 is made of carbon steel, there is a possibility that corrosion has progressed and the thickness has been reduced. Therefore, when there is thinning on the inner surface of the main body barrel 4, a stainless steel contact plate 81 is welded and attached to the portion with a welded portion 82, and the carbon steel portion of the reduced thickness portion is covered. In addition, when the opening part of the steam-filling account 13 and the contact plate 81 interfere, for example, an opening (not shown) slightly larger than the opening part of the steam-filling account 13 is formed in the contact plate 81 so as not to disturb the flow path. ).
[0052]
After that, when the tube bundle 3 is inserted into the main body cylinder 4 and welded to the tube plate 6 to assemble the feed water heater, it is easily corroded by the oxygen gas contained in the high temperature steam of the main body cylinder 4 after entering operation. Since the portion is covered with the stainless steel backing plate 81, the thickness reduction does not proceed and the life of the new feed water heater 80 can be extended.
[0053]
[Ninth Embodiment]
Next, a ninth embodiment of the feed water heater refurbishing method according to the present invention will be described with reference to FIG. In the repair method of the ninth embodiment, when the tube bundle 3 and the drain cooling part 11 are inserted into the temporary cylinder 91 and carried into the installation place integrally with the tube plate 6 provided with the short cylinder 61 on the main body side, The cylinder 61 is assumed to be grooved, and the temporary cylinder 91 is partially covered with the short cylinder 61 and joined by fillet welding.
[0054]
That is, the temporary cylinder 91 is used to protect the heating tube 5 when the tube bundle 3 and the tube plate 6 are carried into the installation place, and to check a leak of the welded portion between the tube plate 6 and the heating tube 5 in the factory. However, if the temporary cylinder 91 and the short cylinder 61 of the tube plate 6 are joined by butt welding, the heated pipe 5 may be damaged when the short cylinder 61 is cut at the installation site, and the tube is opened after cutting. It is necessary to perform pre-processing with a grinder, which requires a work period and cost.
Therefore, a temporary barrel end portion 91a is placed on a part of the short drum 61 of the tube sheet 6 that has been grooved by machining at a factory in advance, and the fillet welded portion 92 is joined thereto.
[0055]
Thereafter, after the integrated temporary cylinders 91 and 91a, the tube bundle 3, the drain cooling unit 11, and the tube sheet 6 are carried into the installation place, the temporary cylinder end 91a and the short cylinder 61 of the tube sheet 6 are removed when the temporary cylinder 91 is removed. If the fillet welded portion 92 is cut with a grinder or the like, the heating tube 5 will not be damaged, and the short drum 61 of the tube sheet 6 has already been grooved, so that welding with the main body drum 4 can be immediately performed. The water heater can be assembled more efficiently and inexpensively.
[0056]
[Tenth embodiment]
Next, a tenth embodiment of a repair method for a feed water heater according to the present invention will be described with reference to FIG. In the repair method of the tenth embodiment, when the tube bundle 3 and the drain cooling unit 11 are inserted into the temporary cylinder 101 and carried into the installation place integrally with the tube plate 6 provided with the short cylinder 61 on the main body side, The cylinder 61 is assumed to be groove-finished, and the temporary cylinder 101 is partially covered with a contact plate 61a provided on the short cylinder 61 of the tube plate 6 and joined by fillet welding.
[0057]
That is, the temporary cylinder 101 protects the heating tube 5 when the tube bundle 3, the drain cooling unit 11, and the tube plate 6 are carried into the installation place, and also checks the leak of the welded portion of the tube plate 6 and the heating tube 5 at the factory. However, when the temporary cylinder 101 and the short cylinder 61 of the tube sheet 6 are joined by butt welding, the heated pipe 5 may be damaged when the short cylinder 61 is cut at the installation location. In addition, it is necessary to perform groove processing with a grinder after cutting, which requires a work period and cost.
Therefore, a part of the provisional cylinder end 101a is partially covered with the contact plate 61a provided on the short cylinder 61 of the tube sheet 6 that has been grooved by machining at a factory in advance, and is joined by the fillet weld 102.
[0058]
Thereafter, the integrated temporary cylinders 101, 101 a, 101 b, the tube bundle 3, the drain cooling unit 11, and the tube sheet 6 are carried into the installation location, and then the temporary cylinder end 101 a and the tube sheet 6 are short when the temporary cylinder 101 is removed. If the fillet welded portion 102 between the barrel 61 and the contact plate 61a is scraped with a grinder or the like, the heating tube 5 is not damaged, the short barrel 61 of the tube plate 6 is not damaged, and the tube plate 6 is short. Since the barrel 61 has already been grooved, welding with the main body barrel 4 can be immediately performed, and the feed water heater can be more efficiently and inexpensively assembled.
[0059]
[Eleventh embodiment]
Next, an eleventh embodiment of a method for repairing a feed water heater according to the present invention will be described with reference to FIG. In the repair method of the eleventh embodiment, when the tube plate 6 and the water chamber 2 are welded at the installation site, the water chamber partition plate 8 which is a structure inside the water chamber 2 is welded and assembled in advance. Complete and place temporarily in the water chamber 2.
[0060]
That is, when the partition plate 8, which is a structure inside the water chamber 2, is assembled and completed and not temporarily placed in the water chamber 2, the water chamber manhole 14 is welded after the water chamber 2 and the tube plate 6 are welded. Therefore, it is necessary to carry the parts of the water chamber partition plate 8 into the water chamber and weld and assemble them in a narrow space in the water chamber 2, which requires a work period and cost.
Therefore, the water chamber partition plate 8 is previously welded to complete the water chamber partition plate assembly, and this assembly is temporarily placed in the water chamber 2 before the tube plate 6 and the water chamber 2 are welded. .
[0061]
Thereafter, after completion of the welding of the water chamber 2 and the tube plate 6, the water chamber partition plate manhole cover 8a is opened, and the welded portion 111 of the end plate 6d provided on the tube plate side and the water chamber partition plate (assembly) 8 is provided. And the welding part 112 of the short pipe 7a from the water supply account 7 and the water chamber partition plate 8 is welded from the inner side. Thereby, a new feed water heater can be assembled much more efficiently.
[0062]
The short pipe 7a is configured such that all of the water supplied from the supply account 7 is guided into the water chamber partition plate 8. The lower end is welded to the water account 7 and the upper end is the water chamber partition plate. 8 is welded. Thereby, mixing with the heated water supply of the outer side of the water chamber partition plate 8 is prevented.
[0063]
The end plate 6d has the same shape as the water chamber partition plate 8 and has a semicircular short cylindrical open-ended structure. If the water chamber partition plate 8 is directly welded to the tube plate 6, it is welded structurally by welding the stainless steel overlay on the tube plate surface (constructed for welding with the heating tube 5) and carbon steel. It becomes difficult to do. Therefore, if the end plate 6d made of carbon steel is welded to the tube plate 6 in advance, and then the end plate 6d and the water chamber partition plate 8 are welded together, the workability and the reliability are improved.
[0064]
[Twelfth embodiment]
Next, a twelfth embodiment of the feed water heater refurbishing method according to the present invention will be described with reference to FIG. In the repair method of this embodiment, the water chamber 2 and the tube sheet 6 of the old feed water heater in the nuclear power plant are melted and separated in the circumferential direction. In this case, the water supply account 7 and the water supply account 9 of the water chamber 2 remain connected to a water supply pipe (not shown) and the legs 12a are fixed to the foundation (not shown) with bolts. Yes. The separated tube plate 6, the tube bundle 3, the drain cooling unit 11, and the main body cylinder 4 of the old feed water heater are further disassembled and carried out of the installation location.
[0065]
On the other hand, the tube plate 6, the tube bundle 3, the drain cooling unit 11, and the main body cylinder 4 newly manufactured integrally at the factory are brought into the installation place, and then assembled into the water chamber 2 by welding to assemble a new water heater 120. Complete.
[0066]
That is, according to the method for assembling the feed water heater of this embodiment, since it is not necessary to carry out and carry in the entire large and heavy feed water heater from the installation location, when carrying out and carrying in the feed water heater Work for repairing buildings and surrounding facilities that interfere with the feed water heater can be greatly reduced, and removal work for removing the thick water pipe connected to the water chamber 2 that normally occurs can also be eliminated. As a result, the amount of assembly work for the water heater can be significantly reduced at the installation location, the construction period required for the replacement of the water heater can be greatly shortened, and the cost required for the replacement can be greatly reduced. it can.
[0067]
Moreover, since the water chamber 2 is reused, materials, labor, and the like required for manufacturing a new feed water heater can be greatly saved. In addition, the amount of waste generated by the replacement work can be greatly reduced.
[0068]
[Thirteenth embodiment]
Next, a thirteenth embodiment of the feed water heater refurbishing method according to the present invention will be described with reference to FIG. The repair method of this embodiment is a modification of the twelfth embodiment, in that the legs 12c of the body barrel 4 and the steam-filled account 13b newly manufactured at the factory are welded and installed at the installation place. This is different from the twelfth embodiment. In this case, it is also possible to provide a leg pad 12b between the leg 12c and the main body 4 and to weld-attach only the pad 12b at the factory. In addition, the opening 13 is processed at the factory at the attachment position of the steam inlet account 13a of the main body barrel 4.
[0069]
That is, according to the assembling method of the feed water heater 130 of this embodiment, the leg 12c or the pipe body 6, the tube bundle 3, the drain cooling unit 11, and the main body cylinder 4 of the main body cylinder 4 newly manufactured integrally at the factory are provided. Since the steam inlet account 13b is not attached, there is no need to renovate the building and surrounding facilities that interfere with the water heater when the water heater is carried in, and the thickness connected to the normal water chamber 2 The removal and restoration work of the meat water supply pipe can also be eliminated. As a result, the amount of assembly work for the water heater can be significantly reduced at the installation location, the construction period required for the replacement of the water heater can be greatly shortened, and the cost required for the replacement can be greatly reduced. it can.
[0070]
Moreover, since the water chamber 2 is reused, materials, labor, and the like required for manufacturing a new feed water heater can be greatly saved. In addition, the amount of waste generated by the replacement work can be greatly reduced.
[0071]
It is possible to appropriately combine the features of the embodiments described above. For example, the overlay welding 71 made of stainless steel of the seventh embodiment or the contact plate 81 of the eighth embodiment can be applied to any of the first to sixth embodiments. Further, the features of the ninth or tenth embodiment can be combined with the features of the other embodiments, and the features of the eleventh embodiment can be combined with the features of the other embodiments.
[0072]
【The invention's effect】
As is apparent from the above description, according to the method for repairing a feed water heater of the present invention, it is possible to reduce the cost required for manufacturing a new feed water heater by reusing part of the existing feed water heater, and New replacement work for the water heater can be performed in a short period of regular inspection.
[Brief description of the drawings]
FIG. 1 is an overall vertical sectional view showing the overall structure of a feed water heater according to the present invention.
FIG. 2 is a schematic development elevation view of the feed water heater in the first embodiment of the repair method for the feed water heater according to the present invention.
FIGS. 3A and 3B are diagrams showing a second embodiment of a repair method for a feed water heater according to the present invention, in which FIG. 3A is an overall elevation view of the repaired feed water heater, and FIG. B section enlarged sectional view of FIG.
FIGS. 4A and 4B are diagrams showing a third embodiment of a repair method for a feed water heater according to the present invention, wherein FIG. 4A is an overall elevation view of the repaired feed water heater, and FIG. B section enlarged sectional view of FIG.
FIGS. 5A and 5B are diagrams showing a fourth embodiment of a repair method for a feed water heater according to the present invention, wherein FIG. 5A is an overall elevation view of the repaired feed water heater, and FIG. ) Is an elevation view schematically showing the state before joining the tube plate / water chamber.
6A and 6B are diagrams showing a fifth embodiment of a repair method for a feed water heater according to the present invention, wherein FIG. 6A is an overall elevation view of the feed water heater after the repair, and FIG. ) Is an elevation view schematically showing the state before joining the tube plate / water chamber.
7A and 7B are views showing a sixth embodiment of a repair method for a feed water heater according to the present invention, in which FIG. 7A is an overall elevation view of the feed water heater after the repair, and FIG. ) Is an elevation view schematically showing the state before joining the tube plate / water chamber.
FIGS. 8A and 8B are diagrams showing a seventh embodiment of a repair method for a feed water heater according to the present invention, wherein FIG. 8A is an overall elevation view of the repaired feed water heater, and FIG. B section enlarged sectional view of FIG.
FIG. 9 is a diagram showing an eighth embodiment of a repair method for a feed water heater according to the present invention, wherein (a) is an overall elevation view of the repaired feed water heater, and (b) is (a) B section enlarged sectional view of FIG.
10A and 10B are views showing a ninth embodiment of the repair method for a feed water heater according to the present invention, in which FIG. 10A is an overall elevation view of the feed water heater after the repair, and FIG. B section enlarged sectional view of FIG.
FIG. 11 is a diagram showing a tenth embodiment of a repair method for a feed water heater according to the present invention, wherein (a) is an overall elevation view of the repaired feed water heater, and (b) is (a) B section enlarged sectional view of FIG.
FIG. 12 is a diagram showing an eleventh embodiment of a repair method for a feed water heater according to the present invention, in which (a) is a sectional view of an essential part in a state where a partition plate is assembled and temporarily arranged in a water chamber; (B) is a principal part sectional drawing in the state which fixed the partition plate in the water chamber, (c) is the C section expanded sectional view of (b).
FIG. 13 is an elevation view schematically showing a state before on-site assembly in a twelfth embodiment of a repair method for a feed water heater according to the present invention;
FIG. 14 is an elevation view schematically showing a state before on-site assembly in a thirteenth embodiment of a feed water heater refurbishing method according to the present invention;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Feed water heater, 2 ... Water chamber, 3 ... Tube bundle, 4 ... Body trunk, 4a ... Body trunk end, 5 ... Heating pipe, 6 ... Tube sheet, 6a ... Tube sheet water chamber side edge, 6b ... Pipe Forged product short torso integrated with plate, 6c ... Tube plate main body side end, 6d ... End plate, 7 ... Water supply account, 7a ... Short tube, 8 ... Water chamber partition plate, 8a ... Water chamber partition plate manhole cover, DESCRIPTION OF SYMBOLS 9 ... Feed-out account, 10 ... Feed water heater, 11 ... Drain cooling part, 12 ... Leg, 12a ... Leg, 12b ... Placing plate, 12c ... Leg, 13 ... Steam-in account, 13a ... Opening, 13b ... Steam-in account , 14 ... Water chamber manhole, 20 ... Feed water heater, 21 ... Short body of carbon steel, 22 ... Welded portion, 23 ... Welded portion, 30 ... Feed water heater, 31 ... Overlay welding of carbon steel, 32 ... Welded portion 40 ... Feed water heater, 41 ... Carbon steel short body, 50 ... Feed water heater, 60 ... Feed water heater, 61 ... Carbon steel short body, 61a ... Short shell base plate, 7 DESCRIPTION OF SYMBOLS ... Feed water heater, 71 ... Overlay welding of stainless steel, 80 ... Feed water heater, 81 ... Stainless steel batting plate, 82 ... Welded part, 91 ... Temporary trunk, 91a ... Temporary trunk end, 92 ... Welded part, DESCRIPTION OF SYMBOLS 101 ... Temporary cylinder, 101a ... Temporary cylinder end part, 101b ... Temporary cylinder end part, 102 ... Welded part, 111 ... Welded part, 112 ... Welded part, 120 ... Feed water heater, 130 ... Feed water heater, 210 ... Supporting plate .

Claims

A method for refurbishing a feed water heater that heats condensed water obtained by cooling steam discharged from a steam turbine and supplies the condensed water to a steam generator,
It said feed water heater has a water chamber having a water inlet seat and the feed water outlet seat retrieving the condensed water after heating is installed so as to be inserted in the middle of the water supply pipe for introducing said condensed water to said water chamber A main body cylinder having a steam inlet and a drain outlet connected through a tube plate, and a plurality of heating pipes connected to the tube plate and disposed in the main body cylinder, and the water supply steam the condensed water introduced is introduced from the steam inlet in the process of being Ru taken downstream of the water supply pipe through the feed water outlet seat through said heating pipe from the upstream side of the tube to the feed water inlet seat Is configured to be heated by the heating tube,
The repair method is
A main body cylinder / tube sheet separating step for separating the existing main body cylinder and the tube sheet;
A body trunk temporary placing step of temporarily placing the existing body trunk after the body trunk and tube sheet separating step;
A tube plate / water that separates the tube plate and the water chamber without moving the water chamber while the water supply account and the water supply account of the existing water chamber are connected to the water supply pipe A chamber separation process;
A tube plate / heating tube manufacturing process that combines and assembles a new tube plate and a plurality of heating tubes,
After the tube plate / heating tube manufacturing step and the tube plate / water chamber separation step, a tube plate / water chamber joining step for joining the water plate to the water chamber by welding the new plurality of heating tubes,
After the main body trunk temporary placing step and the tube sheet / heating tube manufacturing step, the main body trunk / tube plate joining step for joining the temporarily placed existing main body trunk to the new tube plate by welding,
A method of repairing a feed water heater, characterized by comprising:

The body trunk is made of alloy steel,
After the main body cylinder / tube sheet separating step and before the main body cylinder / tube sheet joining step, a short carbon steel short cylinder is welded and joined to the end surface of the main body cylinder facing the tube plate. And further comprising a trunk joining step,
The main body trunk / tube sheet joining step is to weld the short trunk and the tube sheet;
The repair method of the feed water heater of Claim 1 characterized by these.

The body trunk is made of alloy steel,
A build-up welding step in which build-up welding of carbon steel is further provided on an end surface of the main body barrel facing the tube plate after the main body barrel / tube sheet separating step and before the main body barrel / tube sheet joining step. Have
The body trunk / tube sheet joining step is to weld the build-up welding and the tube sheet;
The repair method of the feed water heater of Claim 1 characterized by these.

Prior to the main body barrel and tube sheet joining step, the method further comprises a step of welding and joining a cylindrical short drum to the side of the new tube plate facing the water chamber,
The tube sheet / water chamber joining step is to weld the short body and the water chamber;
The repair method of the feed water heater of Claim 1 characterized by these.

In the new tube sheet, a cylindrical short drum is pre-formed integrally forged on the side toward the water chamber,
The tube sheet / water chamber joining step is to weld the short body and the water chamber;
The repair method of the feed water heater of Claim 1 characterized by these.

Prior to the main body barrel / tube sheet joining step, the method further comprises a step of welding and joining a cylindrical short drum to the side of the new tube plate facing the main body trunk,
The tube sheet / water chamber joining step is to weld ends of the short drum and the main shell;
The repair method of the feed water heater of Claim 1 characterized by these.

The body trunk is made of carbon steel,
Further comprising a step of performing weld welding of stainless steel on at least a part of the thinned portion of the inner surface of the main body trunk after the main body trunk and tube sheet separating step and before the main body trunk and tube sheet joining step;
A method for repairing a feed water heater according to any one of claims 1 to 6.

The body trunk is made of carbon steel,
A process of attaching a stainless steel contact plate by welding so as to cover at least a part of the thinned portion of the inner surface of the main body trunk after the main body trunk / tube sheet separating step and before the main body trunk / tube sheet joining step. Further having
A method for repairing a feed water heater according to any one of claims 1 to 6.

After the tube plate / water chamber separation step, a sealing step of sealing the plurality of heating tubes by covering the plurality of existing heating tubes with a temporary transfer cylinder;
After the sealing step, an unloading step of unloading the plurality of existing heating tubes and the tube plate together with the unloading temporary cylinder,
The method for refurbishing a water heater according to any one of claims 1 to 8, further comprising:

A carrying-in temporary cylinder mounting step for covering a new temporary heating cylinder covering the plurality of heating tubes before the tube plate / water chamber joining step after the tube plate / heating tube manufacturing step;
A leakage inspection step for inspecting leakage of the attachment portions of the new plurality of heating tubes and the tube plate before the tube plate / water chamber joining step after the carrying-in temporary cylinder attachment step,
A carrying-in process of carrying in the new plurality of heating tubes and the tube sheet together with the carrying-in temporary cylinder after the leakage inspection process and before the tube plate / water chamber joining process;
After the carrying-in process and before the tube sheet / water chamber joining step, the carrying-in temporary cylinder removing process for removing the carrying-in temporary cylinder,
The method for repairing a water heater according to claim 1, further comprising:

Before the carrying-in temporary cylinder attachment step, a short cylinder joining step of joining a short cylinder to the side of the new tube sheet facing the main body cylinder,
Before the carrying-in temporary cylinder attachment step, a groove processing step of processing a groove at an end of the short cylinder toward the main body cylinder;
Further comprising
The carrying-in temporary cylinder mounting step includes a step of covering a part of the carrying-in temporary cylinder to the short cylinder and joining it by fillet welding,
The method for repairing a feed water heater according to claim 10, wherein the feed water heater is repaired.

Before the carrying-in temporary cylinder attachment step, a short cylinder joining step of joining a short cylinder to the side of the new tube sheet facing the main body cylinder,
Before the carrying-in temporary cylinder attachment step, a groove processing step of processing a groove at an end of the short cylinder toward the main body cylinder;
Before the carrying-in temporary cylinder mounting step, a step of joining a contact plate to the outer periphery of the short drum by fillet welding;
Further comprising
The carrying-in temporary cylinder mounting step includes a step of covering a part of the carrying-in temporary cylinder on the backing plate and joining the carrying-in temporary cylinder and the backing plate by fillet welding,
The method for repairing a feed water heater according to claim 10, wherein the feed water heater is repaired.

Before the tube plate / water chamber joining step, a water chamber partition plate assembly manufacturing step of assembling a water chamber partition plate assembly with a manhole by welding,
A water chamber partition plate assembly temporary placing step of temporarily placing the water chamber partition plate assembly in the water chamber after the water chamber partition plate assembly manufacturing step and before the tube plate / water chamber joining step;
A water chamber partition plate assembly fixing step of fixing the water chamber partition plate assembly in the water chamber after the tube plate / water chamber joining step;
The method for repairing a feed water heater according to claim 1, further comprising:

A method for refurbishing a feed water heater that heats condensed water obtained by cooling steam discharged from a steam turbine and supplies the condensed water to a steam generator,
It said feed water heater has a water chamber having a water inlet seat and the feed water outlet seat retrieving the condensed water after heating is installed so as to be inserted in the middle of the water supply pipe for introducing said condensed water to said water chamber A main body cylinder having a steam inlet and a drain outlet connected through a tube plate, and a plurality of heating pipes connected to the tube plate and disposed in the main body cylinder, and the water supply steam the condensed water introduced is introduced from the steam inlet in the process of being Ru taken downstream of the water supply pipe through the feed water outlet seat through said heating pipe from the upstream side of the tube to the feed water inlet seat Is configured to be heated by the heating tube,
The repair method is
A tube plate that separates the existing tube plate and the water chamber without moving the water chamber while the water supply account and the water supply account of the existing water chamber are connected to the water supply pipe.・ Water chamber separation process,
A manufacturing process for manufacturing an assembly of a tube plate, a heating tube, and a main body cylinder by coupling a new tube sheet, a plurality of heating tubes, and a main body cylinder to each other;
A transport step for transporting the assembly to the vicinity of the existing water chamber after the manufacturing step;
A joining step for joining the assembly and the water chamber after the transporting step and the tube sheet / water chamber separating step;
A method of repairing a feed water heater, characterized by comprising:

The water supply according to claim 14, further comprising a step of attaching at least a part of a leg of the main body cylinder and a steam inlet account constituting the steam inlet to the outside of the main body cylinder after the transporting step. How to repair the heater.