【０００１】
【発明の属する技術分野】
本発明は、原子力発電プラント、火力発電プラント等における復水器の管板に関し、特に複数に分割された管板を溶接接合する場合の応力集中を低減する構造を有する復水器の管板に関する。
【０００２】
【従来の技術】
図７および図８により、従来の復水器管板を説明する。図７は、原子力発電プラント、火力発電プラント等における復水器の一般的な構造を示す断面立面図であり、図８（ａ）は図７中Ｘ−Ｘ矢視による水室の管板の正面概要図であり、図８（ｂ）は、図８（ａ）中Ｙ−Ｙ矢視図である。
【０００３】
図７に示すように、原子力発電プラント、火力発電プラント等における復水器１は入口側水室２と出口側水室３のそれぞれの管板４の間に冷却管５を取り付けており、海水等の冷却水は入口側水室２に導入され、入口側水室２から冷却管５を通って出口側水室４に至り、出口側水室４から放出される。
【０００４】
一方、復水器１の上部には低圧タービン6 が取り付けられ、低圧タービン6 から復水器１に送り込まれた蒸気は冷却管５と熱交換して凝縮し復水となり、復水器１の底部の出口管７から排出される。
【０００５】
冷却管５は復水器１内部に多数平行に配され、その両端が両側の管板４の冷却管穴８に固定されるが、冷却管穴８は図８（ａ）の管板４の正面概要図中にハッチングで示す冷却管穴群域４ａ内に所定のパターンで多数設けられ、その数は１基の復水器１で冷却管５の１万本分に及ぶものもある。
【０００６】
したがって、復水器１の大きさは、図６において左右１０数メートル、上下１０ｍ近くに及ぶことがあり、据付け現場には全体を一体として搬入することが難しく、復水器１を複数に分割し、複数に分割された管板４と冷却管５を組み立てた上で、現地に搬入後、溶接等の組立てが行われる場合がある。
【０００７】
例えば、図８（ａ）に示すように、復水器１を上下に２分割して上部管板４１、下部管板４２にそれぞれ冷却管５を取付け固定したものを、据付け現場で溶接接合して一体の管板４にする場合、冷却管５の配置される側の反対側の面から溶接を行うことになるが、溶接後、溶接変形により上部管板４１、下部管板４２は図８（ｂ）に破線で示すように、溶接線４３の上下が溶接側に倒れ込むように変形しようとする。
【０００８】
しかし、上部管板４１、下部管板４２はともに既に冷却管５を取り付けてあるので、冷却管穴群域４ａでは変形を起こせず、冷却管穴群域４ａの最も溶接線４３に近い列（１列目）の冷却管穴８−１の近辺の管板４に集中して多大な変形が起き、冷却管５側に溶接線４３が折れ込む形の溶接変形δとなって現れるほか、１列目の冷却管穴８−１周辺の管板４に多大な残留応力Ｆが発生し、管板材料によっては運転中にＳＣＣ（Ｓｔｒｅｓｓ Ｃｏｒｒｏｓｉｏｎ Ｃｒａｃｋ：応力腐食割れ）の発生が懸念されるものとなる。
【０００９】
しかしながら、復水器１において冷却管５は密度の高い配置が求められており、所定の配列を密度の低いものにしたり徒に溶接線４３と１列目の冷却管穴８−１との距離を増したりして残留応力Ｆの作用を回避することも困難であった。
【００１０】
【発明が解決しようとする課題】
本発明は、上記のように復水器を複数に分割して、複数に分割された管板と冷却管を組み立てた上で、現地に搬入後、溶接で組立てが行われる復水器の管板において、溶接後の管板の溶接線に近い１列目の冷却管穴周辺の管板に残留応力が集中して発生することを防止できる復水器管板を提供することを課題とするものである。
【００１１】
【課題を解決するための手段】
（１）本発明は、かかる課題を解決するためになされたものであって、その第１の手段として、複数に分割された管板にそれぞれ所定の配列で設けられた冷却管穴に複数の冷却管の一端を取付け固定したのち、前記複数に分割された管板を互いに溶接接合して一体の管板とする復水器管板において、前記冷却管穴の所定の配列が、前記溶接接合の溶接線から１列目と２列目との配列は正四角配列とし、２列目以降の配列は正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としてなることを特徴とする復水器管板を提供するものである。
【００１２】
第１の手段によれば、溶接接合による残留応力の集中する１列目の冷却管穴周辺の管板での応力集中係数は正四角配列にしたことにより正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列のものより小さくなり、作用する実効的な残留応力は、全ての冷却管穴を同じ配列、正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としたものに比べ、より低減された構造となる。
【００１３】
（２）第２の手段としては、第１の手段の復水器管板において、前記１列目と２列目との配列を、前記正四角配列に代えて正三角配列とし、前記２列目以降の配列を、前記正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列に代えて前記斜め三角配列、斜め四角配列の内の何れか一つの配列としてなることを特徴とする復水器管板を提供するものである。
【００１４】
第２の手段によれば、溶接接合による残留応力の集中する１列目の冷却管穴周辺の管板での応力集中係数は正三角配列にしたことにより斜め三角配列、斜め四角配列の内の何れか一つの配列のものより小さくなり、作用する実効的な残留応力は、全ての冷却管穴を同じ配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としたものに比べ、より低減された構造となるほか、１列目と２列目との配列を正三角配列としたので正四角配列より冷却管穴の密度が高まる。
【００１５】
【発明の実施の形態】
図１および図６に基づき本発明の実施の第１形態にかかる復水器管板を説明する。図１は、従来例を説明した図８（ａ）の管板の正面概要図の上部管板４１の溶接線近傍の部分に相当する部分の拡大図である。図１において、前述の従来のものと同じ部分には同じ符号を付して示し、本実施の形態に理解を容易にするとともに、説明を省略し従来のものと異なる点を主に説明する。なお、上部管板４１、下部管板４２は前述の従来のものと冷却管穴８の配列が異なるが、符号は同じものを付してある。また、このことは、後述の他の実施の形態においても同様とする。
【００１６】
前述の従来のものにおいては、上部管板４１と下部管板４２との溶接後に、溶接線４３近くに発生する残留応力Ｆは、構造上溶接線４３に最も近い１列目の冷却管穴８−１周辺に集中し、第２列目における残留応力は極端に減少することが判明した。それに基づき１列目の冷却管穴の周辺の残留応力の作用を実効的に低減すれば管板４と冷却管５の構成、配列を大きく変更することなく、従来どおりの密度の高い冷却管５の配置を維持したまま上記従来装置の問題は解消しうることを見出し、そのための最適な冷却管穴の配列を有する復水器管板を発明するに到ったものである。
【００１７】
すなわち、本実施の第１形態においては、１列目の冷却管穴８−１と２列目の冷却管穴８との配列を、２列目の冷却管穴８以降の冷却管穴８の配列よりも応力集中係数の少ない配列形に変換し、残留応力の集中する１列目の冷却管穴８−１周辺の管板４（上部管板４１、下部管板４２）に作用する実効的な残留応力Ｆをより低減する構造としたものである。
【００１８】
板材に一定配列の穴８’を設けたときに作用する応力集中係数αは、負荷応力σの向きに対する穴８’の配列形の種類と、穴８’の直径ｄとピッチｐによって一定の傾向がみられる。
【００１９】
図６は板材に一定配列の穴８’を設ける時の、負荷応力σの向きに対応した配列形の種類の説明図である。図６（ａ）に示すように、直径ｄの穴８’がピッチｐで正方形の頂点に配置され負荷応力σ方向に一辺を直角に向ける配置を「正四角配列」Ａ、図６（ｂ）に示すように、直径ｄの穴８’がピッチｐで正三角形の頂点に配置され負荷応力σ方向に一辺を直角に向ける配置を「正三角配列」Ｂ、図６（ｃ）に示すように、直径ｄの穴８’がピッチｐで正三角形の頂点に配置され負荷応力σ方向に一辺を平行に向ける配置を「斜め三角配列」Ｃ、図６（ａ）に示すように、直径ｄの穴８’がピッチｐで正方形の頂点に配置され負荷応力σ方向に一辺を４５°に向ける配置を「斜め四角配列」Ｄとし、本明細書においては各配列名としてその意味で用いることとする。
【００２０】
この場合、正四角配列Ａにおける応力集中係数αａ、正三角配列Ｂにおける応力集中係数αｂ、斜め三角配列Ｃにおける応力集中係数αｃ、斜め四角配列Ｄにおける応力集中係数αｄは、それぞれ穴８’のピッチｐに対する直径ｄの割合（ｄ／ｐ）が大きいほど大きくなると共に、全ての（ｄ／ｐ）の範囲において同じ（ｄ／ｐ）では、αａ＜αｂ＜αｃ＜αｄの関係がある。
【００２１】
一方、復水器１の冷却管５は、冷却効率を高めるため、また冷却管の配置の密度を高めるため、図６に示すもので言えば、蒸気の上下の吹き抜けが少なく密度が高い正三角配列Ｂ、斜め三角配列Ｃまたは斜め四角配列Ｄとされるものが多かった。
【００２２】
本実施の形態は、このような点に注目し、冷却管穴８の配列形を適切なものとして、従来からの復水器１の機能を損なわず、且つ溶接線４３近辺の１列目の冷却管穴８−１周りの応力集中係数を低減でき、実効的な残留応力を低減するようにしたものである。
【００２３】
図１に示すように具体的には、２列目の冷却管穴８以降の冷却管穴８の配列が正三角配列Ｂのものにおいては、１列目の冷却管穴８−１と２列目の冷却管穴８との配列を正四角配列Ａとして、２列目の冷却管穴８以降の冷却管穴８の正三角配列Ｂよりも応力集中係数の小さい配列形に変換した。
【００２４】
一方、図１において正三角配列Ｂと正四角配列Ａの冷却管穴８のピッチと直径は互いに同じであり、ピッチに対する直径の割合（ｄ／ｐ）は同じである。
【００２５】
従って、以上の２点から残留応力Ｆの集中する１列目の冷却管穴８−１周辺の上部管板４１での応力集中係数は小さくなり、作用する実効的な残留応力Ｆは、全ての冷却管穴８、８−１を同じ配列、正三角配列Ｂとしたものに比べ、より低減された構造となる。
【００２６】
図２に基づき本発明の実施の第２形態にかかる復水器管板を説明する。図２は、実施の第１形態を示す図１と同様に、従来例を説明した図８（ａ）の管板の正面概要図の上部管板の溶接線近傍の部分に相当する部分の拡大図である。
【００２７】
本実施の形態においても、１列目の冷却管穴８−１と２列目の冷却管穴８との配列形を、２列目の冷却管穴８以降の冷却管穴８の配列形よりも応力集中係数の少ない配列形に変換し、残留応力の集中する１列目の冷却管穴８−１周辺の上部管板４１に作用する実効的な残留応力Ｆをより低減する構造としたものである。
【００２８】
図２に示すように具体的には、２列目の冷却管穴８以降の冷却管穴８の配列が斜め三角配列Ｃのものにおいて、１列目の冷却管穴８−１と２列目の冷却管穴８との配列を正四角配列Ａとして、２列目の冷却管穴８以降の冷却管穴８の斜め三角配列Ｃよりも応力集中係数の小さい配列形に変換した。
【００２９】
一方、図２に明示されるように、図２において斜め三角配列Ｃの冷却管穴８のピッチより正四角配列Ａでのピッチは大きいので、（ｄ／ｐ）は斜めめ三角配列Ｃより正四角配列Ａの方が小さくなる。
【００３０】
従って、以上の２点から残留応力Ｆの集中する１列目の冷却管穴８−１周辺の上部管板４１での応力集中係数は小さくなり、作用する実効的な残留応力Ｆは、全ての冷却管穴８、８−１を同じ配列、斜め三角配列Ｃとしたものに比べ、より低減された構造となる。
【００３１】
図３に基づき本発明の実施の第３形態にかかる復水器管板を説明する。図３は、実施の第１形態を示す図１と同様に、従来例を説明した図８（ａ）の管板の正面概要図の上部管板の溶接線近傍の部分に相当する部分の拡大図である。
【００３２】
本実施の形態においては、図３に示すように具体的には、２列目の冷却管穴８以降の冷却管穴８の配列が斜め四角配列Ｄのものにおいて、１列目の冷却管穴８−１と２列目の冷却管穴８との配列を正四角配列Ａとして、２列目の冷却管穴８以降の冷却管穴８の斜め四角配列Ｄよりも応力集中係数の小さい配列形に変換した。
【００３３】
一方、図３に明示されるように、図３において斜め四角配列Ｄの冷却管穴８のピッチより正四角配列Ａでのピッチは大きいので、（ｄ／ｐ）は斜め四角配列Ｄより正四角配列Ａの方が小さくなる。
【００３４】
従って、以上の２点から残留応力Ｆの集中する１列目の冷却管穴８−１周辺の上部管板４１での応力集中係数は小さくなり、作用する実効的な残留応力Ｆは、全ての冷却管穴８、８−１を同じ配列、斜め四角配列Ｄとしたものに比べ、より低減された構造となる。
【００３５】
図４に基づき本発明の実施の第４形態にかかる復水器管板を説明する。図４は、実施の第１形態を示す図１と同様に、従来例を説明した図８（ａ）の管板の正面概要図の上部管板の溶接線近傍の部分に相当する部分の拡大図である。
【００３６】
本実施の形態においては、図４に示すように具体的には、２列目の冷却管穴８以降の冷却管穴８の配列が斜め三角配列Ｃのものにおいて、１列目の冷却管穴８−１と２列目の冷却管穴８との配列を正三角配列Ｂとして、２列目の冷却管穴８以降の冷却管穴８の斜め三角配列Ｃよりも応力集中係数の小さい配列形に変換した。
【００３７】
一方、図４に明示されるように、図４において斜め三角配列Ｃの冷却管穴８のピッチより正三角配列Ｂのピッチは大きいので、（ｄ／ｐ）は斜め三角配列Ｃより正三角配列Ｂの方が小さくなる。
【００３８】
従って、以上の２点から残留応力Ｆの集中する１列目の冷却管穴８−１周辺の上部管板４１での応力集中係数は小さくなり、作用する実効的な残留応力Ｆは、全ての冷却管穴８、８−１を同じ配列、斜め三角配列Ｃとしたものに比べ、より低減された構造となる。
【００３９】
また、本実施の形態においては、１列目と２列目との配列を正四角配列Ａに代えて正三角配列Ｂとしたことにより、１列目の冷却管穴８−１の配置密度を正四角配列Ａとするより高いものとできる。
【００４０】
図５に基づき本発明の実施の第５形態にかかる復水器管板を説明する。図５は、実施の第１形態を示す図１と同様に、従来例を説明した図８（ａ）の管板の正面概要図の上部管板の溶接線近傍の部分に相当する部分の拡大図である。
【００４１】
本実施の形態においては、図５に示すように具体的には、２列目の冷却管穴８以降の冷却管穴８の配列が斜め四角配列Ｄのものにおいて、１列目の冷却管穴８−１と２列目との冷却管穴８との配列を正三角配列Ｂとして、２列目の冷却管穴８以降の冷却管穴８の斜め四角配列Ｄよりも応力集中係数の小さい配列形に変換した。
【００４２】
一方、図５に明示されるように、図５において斜め四角配列Ｄの冷却管穴８のピッチより正三角配列Ｂでのピッチは大きいので、（ｄ／ｐ）は斜め四角配列Ｄより正三角配列Ｂの方が小さくなる。
【００４３】
従って、以上の２点から残留応力Ｆの集中する１列目の冷却管穴８−１周辺の上部管板４１での応力集中係数は小さくなり、作用する実効的な残留応力Ｆは、全ての冷却管穴８、８−１を同じ配列、斜め三角配列Ｃとしたものに比べ、より低減された構造となる。
【００４４】
また、本実施の形態においては、１列目と２列目との配列を正四角配列Ａに代えて正三角配列Ｂとしたことにより、１列目の冷却管穴８−１の配置密度を正四角配列Ａとするより高いものとできる。
【００４５】
従って以上のように、上述の何れの実施の形態においても、従来問題となった溶接線４３に対する１列目の冷却管穴８−１周辺の上部管板での応力集中係数が小さくなり、作用する実効的な残留応力が低減することができ、ＳＣＣ（応力腐食割れ）の発生の問題も解消される。
【００４６】
また、上述の実施の形態において１列目の冷却管穴８−１のピッチが、２列目以降の冷却管穴８のピッチより大きくなるということは、１列目に関しては冷却管８−１の設置密度が低下するといことであり、面積当たりの設置数が低下することでもあるが、復水器１全体で約１万本の冷却管８を備えるものとしたとき、上部管板に約５０００本、１列目に配置される冷却管８−１は約１００本程度のオーダーであり、その内の増減は全体で１％未満のレベルとなり全体の冷却管５の密度や性能上において実質的に問題とならない範囲となる。
【００４７】
以上本発明の実施の形態を説明したが、上記実施の形態に限定されるものではなく、本発明の範囲内でその具体的構造に種々の変更を加えてもよいことは言うまでもない。
【００４８】
例えば、上記の実施の形態においては、上部管板４１を示し説明したが、下部管板４２においても全く同様であり、また本発明は、上部、下部に２分割された復水器に限らず、２以上の複数に分割された復水器の管板の溶接部において同様に適用できるものである。
【００４９】
【発明の効果】
（１）請求項１に発明によれば、復水器管板を、複数に分割された管板にそれぞれ所定の配列で設けられた冷却管穴に複数の冷却管の一端を取付け固定したのち、前記複数に分割された管板を互いに溶接接合して一体の管板とする復水器管板において、前記冷却管穴の所定の配列が、前記溶接接合の溶接線から１列目と２列目との配列は正四角配列とし、２列目以降の配列は正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としてなるように構成したので、溶接接合による残留応力の集中する１列目の冷却管穴周辺の管板での応力集中係数は正四角配列にしたため正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列のものより小さくなり、作用する実効的な残留応力は、全ての冷却管穴を同じ配列、正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としたものに比べ、より低減された構造となり、ＳＣＣ（応力腐食割れ）の発生の問題も解消される。
【００５０】
（２）請求項２の発明によれば、請求項１に記載の復水器管板において、前記１列目と２列目との配列を、前記正四角配列に代えて正三角配列とし、前記２列目以降の配列を、前記正三角配列、斜め三角配列、斜め四角配列の内の何れか一つの配列に代えて前記斜め三角配列、斜め四角配列の内の何れか一つの配列としてなるように構成したので、溶接接合による残留応力の集中する１列目の冷却管穴周辺の管板での応力集中係数は正三角配列にしたため斜め三角配列、斜め四角配列の内の何れか一つの配列のものより小さくなり、作用する実効的な残留応力は、全ての冷却管穴を同じ配列、斜め三角配列、斜め四角配列の内の何れか一つの配列としたものに比べ、より低減された構造となり、ＳＣＣ（応力腐食割れ）の発生の問題も解消されるが、また、１列目と２列目との配列を正三角配列としたので正四角配列より冷却管穴の密度を高められる。
【図面の簡単な説明】
【図１】本発明の実施の第１形態にかかる復水器管板の説明図であり、本実施の形態における図８（ａ）の管板の正面概要図の上部管板の溶接線近傍の部分に相当する部分の拡大図である。
【図２】本発明の実施の第２形態にかかる復水器管板の説明図であり、本実施の形態における図１と同様部分の拡大図である。
【図３】本発明の実施の第３形態にかかる復水器管板の説明図であり、本実施の形態における図１と同様部分の拡大図である。
【図４】本発明の実施の第４形態にかかる復水器管板の説明図であり、本実施の形態における図１と同様部分の拡大図である。
【図５】本発明の実施の第５形態にかかる復水器管板の説明図であり、本実施の形態における図１と同様部分の拡大図である。
【図６】負荷応力の向きに対する穴の配列形の説明図である。
【図７】従来の復水器の一般的な構造を示す断面立面図である。
【図８】（ａ）は図７中Ｘ−Ｘ矢視による水室の管板の正面概要図であり、（ｂ）は（ａ）中Ｙ−Ｙ矢視図である。
【符号の説明】
１ 復水器
２ 入口側水室
３ 出口側水室
４ 管板
５ 冷却管
６ 低圧タービン
７ 出口管
８ 冷却管穴
８−１ １列目の冷却管穴
４１ 上部管板
４２ 下部管板
４３ 溶接線
Ａ 正四角配列
Ｂ 正三角配列
Ｃ 斜め三角配列
Ｄ 斜め四角配列[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a condenser tube sheet in a nuclear power plant, a thermal power plant, and the like, and more particularly, to a condenser tube sheet having a structure that reduces stress concentration when welding a plurality of divided tube sheets. .
[0002]
[Prior art]
A conventional condenser tube sheet will be described with reference to FIGS. FIG. 7 is a sectional elevation view showing a general structure of a condenser in a nuclear power plant, a thermal power plant or the like, and FIG. 8 (a) is a water chamber tube plate as viewed in the direction of arrows XX in FIG. FIG. 8B is a view taken in the direction of arrows Y-Y in FIG. 8A.
[0003]
As shown in FIG. 7, the condenser 1 in a nuclear power plant, a thermal power plant, or the like has a cooling pipe 5 attached between the tube plates 4 of the inlet side water chamber 2 and the outlet side water chamber 3, Is introduced into the inlet-side water chamber 2, passes through the cooling pipe 5 from the inlet-side water chamber 2, reaches the outlet-side water chamber 4, and is discharged from the outlet-side water chamber 4.
[0004]
On the other hand, a low-pressure turbine 6 is attached to the upper part of the condenser 1, and the steam sent from the low-pressure turbine 6 to the condenser 1 exchanges heat with the cooling pipe 5 to condense and become condensate. It is discharged from the outlet pipe 7 at the bottom.
[0005]
A large number of cooling pipes 5 are arranged in parallel in the condenser 1 and both ends thereof are fixed to the cooling pipe holes 8 of the tube plates 4 on both sides. The cooling pipe holes 8 are formed on the tube plate 4 of FIG. In the cooling pipe hole group area 4a indicated by hatching in the front schematic view, a large number of them are provided in a predetermined pattern, and the number of the condenser pipes 1 may reach 10,000 of the cooling pipes 5.
[0006]
Therefore, the size of the condenser 1 may reach 10 meters on the left and right and nearly 10 meters on the upper and lower sides in FIG. 6, and it is difficult to carry the whole into the installation site as a whole, and the condenser 1 is divided into a plurality of parts. And after assembling the tube plate 4 and the cooling pipe 5 which were divided | segmented into plurality, after carrying in to the spot, assembly, such as welding, may be performed.
[0007]
For example, as shown in FIG. 8 (a), the condenser 1 is divided into two parts, and the cooling pipes 5 are attached and fixed to the upper tube sheet 41 and the lower tube sheet 42, respectively, and welded and joined at the installation site. When the integrated tube sheet 4 is formed, welding is performed from the surface opposite to the side where the cooling pipe 5 is disposed. After welding, the upper tube sheet 41 and the lower tube sheet 42 are formed by welding deformation as shown in FIG. As shown by a broken line in (b), the welding line 43 tends to be deformed so that the upper and lower sides of the welding line 43 fall on the welding side.
[0008]
However, since both the upper tube plate 41 and the lower tube plate 42 have already been fitted with the cooling pipe 5, the cooling pipe hole group area 4 a is not deformed, and the line closest to the weld line 43 in the cooling pipe hole group area 4 a ( In the first row), a large amount of deformation occurs in the vicinity of the tube plate 4 in the vicinity of the cooling tube hole 8-1 and appears as a welding deformation δ in which the welding line 43 is folded into the cooling tube 5 side. A great amount of residual stress F is generated in the tube plate 4 around the cooling tube hole 8-1 in the row, and depending on the tube plate material, there is a concern that SCC (Stress Corrosion Crack) may occur during operation. Become.
[0009]
However, in the condenser 1, the cooling pipe 5 is required to be arranged with a high density, and a predetermined arrangement is made to have a low density, or the distance between the welding line 43 and the cooling pipe hole 8-1 in the first row is easily set. It is also difficult to avoid the action of the residual stress F by increasing
[0010]
[Problems to be solved by the invention]
The present invention divides the condenser into a plurality of parts as described above, assembles the divided pipe plate and the cooling pipe, and then carries the assembly by welding after carrying it to the site. It is an object of the present invention to provide a condenser tube sheet that can prevent residual stress from being concentrated on the tube sheet around the cooling tube hole in the first row close to the weld line of the tube sheet after welding. Is.
[0011]
[Means for Solving the Problems]
(1) The present invention has been made to solve such a problem, and as a first means, a plurality of cooling tube holes provided in a predetermined arrangement on a plurality of divided tube plates are provided. In the condenser tube plate, after attaching and fixing one end of the cooling pipe, the tube sheets divided into a plurality of parts are welded together to form an integral tube sheet, the predetermined arrangement of the cooling pipe holes is the weld joint The arrangement of the first and second rows from the weld line is a regular square arrangement, and the arrangement after the second row is any one of a regular triangular arrangement, a diagonal triangular arrangement, and a diagonal square arrangement. A condenser tube sheet having the characteristics is provided.
[0012]
According to the first means, the stress concentration coefficients in the tube plate around the first row of cooling pipe holes where residual stresses due to welding are concentrated are arranged in a regular square arrangement, so that a regular triangular arrangement, a diagonal triangular arrangement, and a diagonal square are provided. The effective residual stress that is smaller than that of any one of the arrays and acts is that any one of the cooling tube holes in the same array, regular triangle array, diagonal triangle array, or diagonal square array. Compared to one array, the structure is reduced.
[0013]
(2) As the second means, in the condenser tube plate of the first means, the arrangement of the first row and the second row is a regular triangular arrangement instead of the regular square arrangement, and the two rows The array after the eye is replaced with any one of the regular triangular array, the diagonal triangular array, and the diagonal square array, and the array is one of the diagonal triangular array and the diagonal square array. It provides a condenser tube sheet.
[0014]
According to the second means, the stress concentration factor in the tube plate around the cooling tube hole in the first row where the residual stress due to welding is concentrated is an equilateral triangle arrangement, so that one of the oblique triangle arrangement and the oblique square arrangement is included. The effective residual stress that acts smaller than that of any one of the arrangements, compared to the case where all the cooling pipe holes are arranged in the same arrangement, diagonal triangle arrangement, diagonal square arrangement, In addition to a more reduced structure, the arrangement of the first and second rows is a regular triangular arrangement, so that the density of the cooling tube holes is higher than that of the regular square arrangement.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A condenser tube sheet according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 6. FIG. 1 is an enlarged view of a portion corresponding to a portion in the vicinity of the weld line of the upper tube sheet 41 in the front schematic view of the tube sheet of FIG. In FIG. 1, the same parts as those of the above-described conventional ones are denoted by the same reference numerals, and the present embodiment is made easy to understand. The upper tube plate 41 and the lower tube plate 42 have the same reference numerals, although the arrangement of the cooling tube holes 8 is different from that of the conventional tube plate. This also applies to other embodiments described later.
[0016]
In the above-mentioned conventional one, the residual stress F generated near the weld line 43 after welding the upper tube sheet 41 and the lower tube sheet 42 is the cooling tube hole 8 in the first row closest to the weld line 43 in structure. It was found that the residual stress in the second row was extremely reduced with concentration around -1. Based on this, if the action of the residual stress around the cooling tube hole in the first row is effectively reduced, the cooling tube 5 having the same high density as the conventional one can be obtained without greatly changing the configuration and arrangement of the tube plate 4 and the cooling tube 5. It has been found that the problems of the above-mentioned conventional apparatus can be solved while maintaining the arrangement of the above, and a condenser tube plate having an optimal arrangement of cooling pipe holes for that purpose has been invented.
[0017]
That is, in the first embodiment, the arrangement of the cooling tube holes 8-1 in the first row and the cooling tube holes 8 in the second row is the same as that of the cooling tube holes 8 after the cooling tube holes 8 in the second row. It is converted into an array shape having a smaller stress concentration coefficient than the array, and effectively acts on the tube plate 4 (upper tube plate 41, lower tube plate 42) around the cooling tube hole 8-1 in the first row where residual stress is concentrated. The residual stress F is further reduced.
[0018]
The stress concentration factor α acting when the holes 8 ′ having a constant arrangement are provided in the plate material has a constant tendency depending on the type of arrangement of the holes 8 ′ with respect to the direction of the load stress σ, the diameter d and the pitch p of the holes 8 ′. Is seen.
[0019]
FIG. 6 is an explanatory diagram of the types of arrangement corresponding to the direction of the load stress σ when the holes 8 ′ having a constant arrangement are provided in the plate material. As shown in FIG. 6 (a), a hole 8 'having a diameter d is arranged at the apex of a square at a pitch p, and an arrangement in which one side is oriented at right angles in the direction of the load stress σ is "regular square arrangement" A, FIG. 6 (b). As shown in FIG. 6B, an arrangement in which holes 8 ′ having a diameter d are arranged at the apexes of equilateral triangles at a pitch p and one side is oriented at right angles in the direction of the load stress σ is as shown in “regular triangle arrangement” B, FIG. , An arrangement in which holes 8 'of diameter d are arranged at the apexes of equilateral triangles at a pitch p and one side is parallel to the direction of load stress σ is "diagonal triangular arrangement" C, as shown in FIG. An arrangement in which the holes 8 ′ are arranged at the apexes of the square with a pitch p and one side is directed to 45 ° in the direction of the load stress σ is referred to as “diagonal square arrangement” D, and in this specification, it is used as the meaning of each arrangement name. .
[0020]
In this case, the stress concentration coefficient αa in the regular square array A, the stress concentration coefficient αb in the regular triangular array B, the stress concentration coefficient αc in the diagonal triangular array C, and the stress concentration coefficient αd in the diagonal square array D are respectively the pitches of the holes 8 ′. The larger the ratio of the diameter d to p (d / p), the larger the ratio, and in the same range (d / p) in the range of all (d / p), there is a relationship of αa <αb <αc <αd.
[0021]
On the other hand, the cooling pipe 5 of the condenser 1 is a regular triangle having a high density with less up-and-down flow of steam in order to increase cooling efficiency and to increase the density of the arrangement of cooling pipes, as shown in FIG. Many of them were array B, diagonal triangular array C, or diagonal square array D.
[0022]
The present embodiment pays attention to such a point, makes the arrangement shape of the cooling pipe holes 8 appropriate, does not impair the function of the conventional condenser 1, and is in the first row near the weld line 43. The stress concentration factor around the cooling pipe hole 8-1 can be reduced, and the effective residual stress is reduced.
[0023]
Specifically, as shown in FIG. 1, when the arrangement of the cooling tube holes 8 after the cooling tube holes 8 in the second row is an equilateral triangle arrangement B, the cooling tube holes 8-1 and the second row in the first row are arranged. The array with the cooling tube holes 8 of the eyes was converted into a regular square array A, which was converted into an array shape having a smaller stress concentration coefficient than the regular triangular array B of the cooling tube holes 8 after the cooling tube holes 8 in the second row.
[0024]
On the other hand, in FIG. 1, the pitches and diameters of the cooling tube holes 8 of the regular triangular array B and the regular square array A are the same, and the ratio of the diameter to the pitch (d / p) is the same.
[0025]
Therefore, the stress concentration coefficient in the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress F concentrates from the above two points becomes small, and the effective residual stress F acting on all the Compared with the case where the cooling tube holes 8 and 8-1 are arranged in the same arrangement and regular triangle arrangement B, the structure is further reduced.
[0026]
A condenser tube sheet according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is an enlarged view of a portion corresponding to a portion in the vicinity of the weld line of the upper tube sheet in the schematic front view of the tube sheet in FIG. 8 (a) illustrating the conventional example, as in FIG. 1 showing the first embodiment. FIG.
[0027]
Also in the present embodiment, the arrangement form of the cooling pipe holes 8-1 in the first row and the cooling pipe holes 8 in the second row is more than the arrangement form of the cooling pipe holes 8 in the second and subsequent rows. Is converted into an array having a small stress concentration coefficient, and the effective residual stress F acting on the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress is concentrated is further reduced. It is.
[0028]
Specifically, as shown in FIG. 2, in the case where the arrangement of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row is an oblique triangular arrangement C, the first row of cooling pipe holes 8-1 and the second row are arranged. The array with the cooling tube holes 8 was converted into a regular square array A, and the array was converted to an array with a smaller stress concentration coefficient than the diagonal triangular array C of the cooling tube holes 8 after the cooling tube holes 8 in the second row.
[0029]
On the other hand, as clearly shown in FIG. 2, the pitch in the regular square array A is larger than the pitch of the cooling tube holes 8 in the diagonal triangular array C in FIG. The square array A is smaller.
[0030]
Therefore, the stress concentration coefficient in the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress F concentrates from the above two points becomes small, and the effective residual stress F acting on all the Compared with the case where the cooling tube holes 8 and 8-1 are arranged in the same arrangement and the diagonal triangular arrangement C, the structure is further reduced.
[0031]
A condenser tube sheet according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is an enlarged view of a portion corresponding to a portion in the vicinity of the weld line of the upper tube sheet in the schematic front view of the tube sheet in FIG. 8 (a) illustrating the conventional example, as in FIG. 1 showing the first embodiment. FIG.
[0032]
In the present embodiment, specifically, as shown in FIG. 3, in the case where the arrangement of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row is an oblique square arrangement D, the cooling pipe holes in the first row 8-1 and the array of cooling tube holes 8 in the second row are regular square arrays A, and the array shape has a smaller stress concentration coefficient than the diagonal square array D of the cooling tube holes 8 after the cooling tube holes 8 in the second row. Converted to.
[0033]
On the other hand, as clearly shown in FIG. 3, the pitch in the regular square array A is larger than the pitch of the cooling tube holes 8 in the diagonal square array D in FIG. Array A is smaller.
[0034]
Therefore, the stress concentration coefficient in the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress F concentrates from the above two points becomes small, and the effective residual stress F acting on all the Compared with the case where the cooling tube holes 8 and 8-1 are arranged in the same arrangement and the oblique square arrangement D, the structure is further reduced.
[0035]
A condenser tube sheet according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is an enlarged view of a portion corresponding to a portion in the vicinity of the weld line of the upper tube sheet in the schematic front view of the tube sheet of FIG. 8 (a) illustrating the conventional example, as in FIG. 1 showing the first embodiment. FIG.
[0036]
In the present embodiment, as shown in FIG. 4, specifically, in the case where the arrangement of the cooling tube holes 8 after the cooling tube holes 8 in the second row is an oblique triangular arrangement C, the cooling tube holes in the first row 8-1 and the arrangement of the cooling pipe holes 8 in the second row are regular triangular arrangement B, and the arrangement form has a smaller stress concentration coefficient than the diagonal triangular arrangement C of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row. Converted to.
[0037]
On the other hand, as clearly shown in FIG. 4, since the pitch of the regular triangular array B is larger than the pitch of the cooling tube holes 8 of the diagonal triangular array C in FIG. 4, (d / p) is a regular triangular array than the diagonal triangular array C. B is smaller.
[0038]
Therefore, the stress concentration coefficient in the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress F concentrates from the above two points becomes small, and the effective residual stress F acting on all the Compared with the case where the cooling tube holes 8 and 8-1 are arranged in the same arrangement and the diagonal triangular arrangement C, the structure is further reduced.
[0039]
In the present embodiment, the arrangement density of the cooling tube holes 8-1 in the first row is changed by replacing the arrangement in the first row and the second row with a regular triangle arrangement B instead of the regular square arrangement A. It can be higher than the regular square array A.
[0040]
A condenser tube sheet according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is an enlarged view of the portion corresponding to the portion in the vicinity of the weld line of the upper tube sheet in the schematic front view of the tube sheet of FIG. 8 (a) illustrating the conventional example, as in FIG. 1 showing the first embodiment. FIG.
[0041]
In the present embodiment, specifically, as shown in FIG. 5, in the case where the arrangement of the cooling pipe holes 8 after the cooling pipe holes 8 in the second row is the diagonal square arrangement D, the cooling pipe holes in the first row An array having a smaller stress concentration coefficient than the diagonal square array D of the cooling tube holes 8 after the cooling tube hole 8 in the second row is defined as an equilateral triangular array B with the arrangement of the cooling tube holes 8 in the second row and the 8-1. Converted into a shape.
[0042]
On the other hand, as clearly shown in FIG. 5, since the pitch in the regular triangular array B is larger than the pitch of the cooling tube holes 8 in the diagonal square array D in FIG. 5, (d / p) is a regular triangle from the diagonal square array D. Array B is smaller.
[0043]
Therefore, the stress concentration coefficient in the upper tube plate 41 around the cooling tube hole 8-1 in the first row where the residual stress F concentrates from the above two points becomes small, and the effective residual stress F acting on all the Compared with the case where the cooling tube holes 8 and 8-1 are arranged in the same arrangement and the diagonal triangular arrangement C, the structure is further reduced.
[0044]
In the present embodiment, the arrangement density of the cooling tube holes 8-1 in the first row is changed by replacing the arrangement in the first row and the second row with a regular triangle arrangement B instead of the regular square arrangement A. It can be higher than the regular square array A.
[0045]
Therefore, as described above, in any of the above-described embodiments, the stress concentration coefficient in the upper tube sheet around the cooling tube hole 8-1 in the first row with respect to the weld line 43, which has been a problem in the past, is reduced. Effective residual stress can be reduced, and the problem of occurrence of SCC (stress corrosion cracking) is also eliminated.
[0046]
Further, in the above-described embodiment, the pitch of the cooling tube holes 8-1 in the first row is larger than the pitch of the cooling tube holes 8 in the second and subsequent rows. The installation density per unit area is reduced, and the number of installations per area is also reduced. However, when the condenser 1 as a whole is provided with about 10,000 cooling pipes 8, about the upper tube sheet The number of the cooling pipes 8-1 arranged in the first row is about 100, and the increase / decrease is less than 1% as a whole, and the density and performance of the whole cooling pipe 5 are substantially reduced. Is not a problem.
[0047]
The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention.
[0048]
For example, in the above embodiment, the upper tube plate 41 is shown and described. However, the same applies to the lower tube plate 42, and the present invention is not limited to the condenser divided into the upper part and the lower part. It can be similarly applied to the welded portion of the tube sheet of the condenser divided into two or more.
[0049]
【The invention's effect】
(1) According to the first aspect of the present invention, after the condenser tube plate is fixed by attaching one end of the plurality of cooling tubes to the cooling tube holes provided in a predetermined arrangement on the divided tube plates, respectively. In the condenser tube sheet, the plurality of divided tube sheets are welded together to form an integral tube sheet, and the predetermined arrangement of the cooling tube holes is arranged in a first row and a second row from the weld line of the weld joint. Since the arrangement with the row is a regular square arrangement, the arrangement after the second row is arranged as one of a regular triangle arrangement, an oblique triangle arrangement, and an oblique square arrangement. Since the stress concentration coefficient in the tube plate around the cooling tube hole in the first row where is concentrated is a regular square array, it becomes smaller than any one of the regular triangle array, the diagonal triangle array, and the diagonal square array, The effective residual stress that acts is the same arrangement, equilateral triangle arrangement of all cooling pipe holes. , Oblique triangular arrangement, compared with those with any one sequence of the oblique square array, becomes more reduced structure, a problem of occurrence of SCC (Stress Corrosion Cracking) is also eliminated.
[0050]
(2) According to the invention of claim 2, in the condenser tube plate according to claim 1, the arrangement of the first row and the second row is a regular triangle arrangement instead of the regular square arrangement, The array in the second and subsequent columns is replaced with any one of the regular triangular array, the diagonal triangular array, and the diagonal square array, and is one of the diagonal triangular array and the diagonal square array. Since the stress concentration coefficient in the tube plate around the cooling tube hole in the first row where the residual stress is concentrated due to the welding joint is an equilateral triangle arrangement, either one of the oblique triangle arrangement and the oblique square arrangement is used. Effective residual stress that is smaller than that of the array and acts is reduced compared to the case where all the cooling pipe holes are arranged in one of the same array, diagonal triangle array, and diagonal square array. It becomes a structure and the problem of the occurrence of SCC (stress corrosion cracking) is solved. That, but also increased the density of the cooling pipe hole than a square array so the sequence of the first and second columns were positive triangular array.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a condenser tube sheet according to a first embodiment of the present invention, in the vicinity of the weld line of the upper tube sheet in the front schematic view of the tube sheet of FIG. 8 (a) in the present embodiment. It is an enlarged view of a portion corresponding to the portion.
FIG. 2 is an explanatory view of a condenser tube plate according to a second embodiment of the present invention, and is an enlarged view of the same portion as FIG. 1 in the present embodiment.
FIG. 3 is an explanatory view of a condenser tube plate according to a third embodiment of the present invention, and is an enlarged view of the same portion as FIG. 1 in the present embodiment.
FIG. 4 is an explanatory view of a condenser tube plate according to a fourth embodiment of the present invention, and is an enlarged view of the same portion as FIG. 1 in the present embodiment.
FIG. 5 is an explanatory view of a condenser tube plate according to a fifth embodiment of the present invention, and is an enlarged view of the same portion as FIG. 1 in the present embodiment.
FIG. 6 is an explanatory diagram of an array of holes with respect to the direction of load stress.
FIG. 7 is a sectional elevation view showing a general structure of a conventional condenser.
8A is a schematic front view of a tube sheet of a water chamber as viewed in the direction of arrows XX in FIG. 7, and FIG. 8B is a view in the direction of arrows YY in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Condenser 2 Inlet side water chamber 3 Outlet side water chamber 4 Tube plate 5 Cooling tube 6 Low pressure turbine 7 Outlet tube 8 Cooling tube hole 8-1 1st row cooling tube hole 41 Upper tube plate 42 Lower tube plate 43 Welding Line A Regular square array B Regular triangle array C Diagonal triangle array D Diagonal square array