JP3956602B2 - Manufacturing method of steam turbine rotor shaft - Google Patents

Description

【００５２】
表２は供試材の６５０℃のクリープ破断強度を示すものである。表に示すように、０.００６％ を越えるＡｌの含有は本発明の特定の組成においては特に著しくクリープ破断強度を低めるので、それ以下にすべきである。更に、Ｎｏ．１の比較材に対してＣｏを２％以下又、Ｎｉを０．２％以下に低めたＮｏ．２及び３は１０万時間の長時間側程クリープ破断強度が１０．５ｋｇ/ｍｍ²以上に向上しており、更に、（Ｎｉ／Ｃｏ）比を０．０９以下とした０．０３４及び０．００６７とより小さいもの程長時間側程クリープ破断強度が優れていることが分かる。
【００５３】
【表２】

【００５４】
本実施例におけるロータシャフトは初段動翼への蒸気温度入口温度が６００℃以上の高圧タービン，中圧タービン又は高圧部と中圧部を一体にした高中圧一体型蒸気タービンに用いることができる。これらの蒸気タービンは互いに反対向きの外側に向かって流れる複流構造のブレード植込み構造を有するロータシャフトとなる。更に、いずれのロータシャフトのジャーナル部にもベーナイト組織を有するＣｒ−Ｍｏ低合金鋼の肉盛又はそのスリーブが設けられる。特に、本実施例においては、高圧タービン６００℃，中圧タービン６２０℃、又は高圧タービン及び中圧タービン６２０℃の蒸気温度を用いる単機出力で１０００ＭＷ以上の超々臨界圧発電プラントに好適である。更に、これらの蒸気温度として６３０〜６５０℃への適用が可能である。
【００５５】
〔実施例２〕
表３は本発明に係る蒸気温度６２５℃，１０５０ＭＷ蒸気タービンの主な仕様である。本実施例は、クロスコンパウンド型４流排気，低圧タービンにおける最終段動翼の翼部長さが４３インチであり、タービン構成ＡはＨＰ−ＩＰ及びＬＰ２台で3000ｒ／min、タービン構成ＢはＨＰ−ＬＰ及びＩＰ−ＬＰで各々同じく３０００ｒ／minの回転数を有し、ＨＰ、ＩＰの高温に晒されるロータシャフトには実施例１で得られた結果を基に表４に示す本発明の高強度１２Ｃｒ鋼が用いられる。高圧部（ＨＰ）の蒸気温度は６２５℃，２５０kgｆ／cm²の圧力であり、中圧部(ＩＰ）の蒸気温度は６２５℃に再熱器によって加熱され、４５〜６５kgｆ／cm² の圧力で運転される。低圧部(ＬＰ)は蒸気温度は４００℃で入り、１００℃以下，７２２mmＨｇの真空で復水器に送られる。
【００５６】
高圧タービン及び中圧タービンをタンデムに結合した軸受間距離、及びタンデムに結合した２台の前記低圧タービンの軸受間距離の合計は約３１.５ｍであり、コンパクトになっている。
【００５７】
【表３】

【００５８】
図１は表３のタービン構成のＡにおける高圧及び中圧蒸気タービンをタンデム二結合した構造の断面構成図である。
【００５９】
（高圧蒸気タービン）
図中、左側の高圧蒸気タービンは高圧内部車室１８とその外側の高圧外部車室１９内に高圧動翼１６を植設した高圧車軸２３が設けられる。高温高圧の蒸気は、主蒸気管を通って、主蒸気入口を構成するフランジ，エルボ２５より主蒸気入口２８を通り、ノズルボックス３８より初段複流の動翼に導かれる。初段は複流であり、片側に８段設けられる。これらの動翼に対応して各々静翼が設けられる。動翼は鞍型ダブティル型式，ダブルティノン，初段翼部長さが約３５mmである。車軸間の長さは約５.３ ｍ及び静翼部に対応する部分で最も小さい部分の直径は約７１０mmであり、直径に対する長さの比は約８.２である。
【００６０】
後述する表４に示す材料を初段ブレード及び初段ノズルに使用し、他のブレード及びノズルはいずれもＷ，Ｃｏ及びＢを含まない１２％Ｃｒ系鋼によって構成したものである。動翼の翼部の長さは初段が３５〜５０mm、２段目から最終段になるに従って各段で長くなっており、特に蒸気タービンの出力によって２段から最終段までの長さが６５〜１８０mmであり、段数は９〜１２段で、各段の翼部の長さは下流側が上流側に対して隣り合う長さで１.１０〜１.１５の割合で長くなっているとともに、下流側でその比率が徐々に大きくなっている。
【００６１】
（中圧蒸気タービン）
図中、右側の中圧蒸気タービンは高圧蒸気タービンより排出された蒸気を再度６２５℃に再熱器によって加熱された蒸気によって高圧蒸気タービンと共に発電機を回転させるもので、３０００回／min の回転数によって回転される。中圧タービンは高圧タービンと同様に中圧内部第２車室２１と中圧外部車室２２とを有し、中圧動翼１７と対抗して静翼が設けられる。動翼１７は６段で複流となり、中圧車軸の長手方向に対しほぼ左右対称の構造に設けられ、初段翼長さ約１００mm，最終段翼長さ約２３０mmである。初段，２段のダブティルは逆クリスマスツリー型である。最終段動翼前の静翼に対応する部分のロータシャフトの直径は約６３０mmであり、軸受間距離の５．８ｍに対して約９.２倍である。
【００６２】
本実施例においては後述する表４に示す材料を初段ブレード，初段ノズルに使用する他はＷ，Ｃｏ及びＢを含まない１２％Ｃｒ系鋼が用いられる。本実施例における動翼の翼部の長さは初段から最終段になるに従って各段で長くなっており、蒸気タービンの出力によって初段から最終段までの長さが６０〜３００mmで、６〜９段で、各段の翼部の長さは下流側が上流側に対して隣り合う長さで１.１〜１.２の割合で長くなっている。
【００６３】
ロータシャフトは、動翼の植込み部が静翼に対応する部分に比較して直径が大きくなっており、その軸方向の幅は動翼の翼部長さが大きい程大きくなっている。その幅の動翼の翼部長さに対する比率は初段から最終段で０.３５〜０.８であり、初段から最終段になるに従って段階的に小さくなっている。
【００６４】
高圧タービンの初段タービン翼は鞍型の植込みを有し、また高圧タービンの２段以降及び中圧タービンの全段のタービン翼は逆クリスマスツリー型である。
【００６５】
（低圧蒸気タービン）
図２は低圧タービンの断面図である。低圧タービンは２基タンデムに結合され、ほぼ同じ構造を有している。各々動翼４１は左右に８段あり、左右ほぼ対称になっており、また動翼に対応して静翼４２が設けられる。ノズルボックス４５は複流型である。
【００６６】
ロータシャフト４４には、重量で、Ｃ0.2〜0.3％,Ｓｉ0.03〜0.1％、Ｍｎ0.1〜0.2％、P0.01％以下、S0.01％以下、Ｎｉ3.5〜4.5％、Ｃｒ1.8〜2.5％、Ｍｏ0.3〜0.5％、Ｖ0.1〜0.2％、Ａｌ0.01％以下、Ｓｎ0.005％以下、Ａｓ0.005％以下、Ｓｂ0.001％以下を含むスーパークリーンされた全焼戻しベーナイト鋼の鍛鋼が用いられる。これらの鋼は熱間鍛造後８４０℃×３ｈ加熱後、１００℃／ｈで冷却する焼入れ後、５７５℃×３２ｈ加熱する焼戻しが施され、全焼戻しベーナイト組織を有する。０.０２％耐力８０kg／mm²以上，０.２％耐力８７.５kg／mm²以上，引張強さ１００kg／mm² 以上，Ｖノッチ衝撃値１０kg−ｍ以上，ＦＡＴＴは−２０℃以下と高強度及び高靭性を有し、本実施例の最終段動翼として翼部長さ４３〜５０インチの植設ができるものであった。
【００６７】
本実施例の４３インチ翼には、Ｃ０．１４％、Ｓｉ０．０４％、Ｍｎ０．１５％、Ｃｒ１１．５％、Ｎｉ２．６０％、Ｍｏ２．３０％、Ｖ０．２７％、Ｎｂ０．１０％、Ｎ０．０７％を含むマルテンサイト鋼を用い、焼き入れ及び焼き戻しを行った。このものの引張強さが１３４ｋｇ/ｍｍ²、Ｖノッチ衝撃値が５．０ｋｇ―ｍ/ｃｍ²であった。
【００６８】
最終段以外の動翼及び静翼にはいずれもＭｏを０.１％ 含有する１２％Ｃｒ鋼が用いられる。内外部ケーシング材にはＣ０.２５％ の鋳鋼が用いられる。本実施例における軸受４３での中心間距離は７５００mmで、静翼部に対応するロータシャフトの直径は約１２８０mm，動翼植込み部での直径は２２７５mmである。
【００６９】
蒸気中の水滴によるエロージョンを防止するためのエロージョンシールドには重量で、Ｃ１.０％，Ｃｒ２８.０％及びＷ４.０％ を含むＣｏ基合金のステライト板を電子ビーム溶接で接合した。コンティニュアスカバーは本実施例においては全体一体の鍛造後に切削加工によって形成されたものである。尚、コンティニュアスカバーは機械的に一体に形成することもできる。
【００７０】
本実施例の低圧タービンは動翼植込み部の軸方向の幅が初段〜３段，４段，５段，６〜７段及び８段の４段階で徐々に大きくなっており、最終段の幅は初段の幅に比べ約２.５倍と大きくなっている。
【００７１】
また、静翼部に対応する部分の直径は小さくなっており、その部分の軸方向の幅は初段動翼側から５段目，６段目及び７段目の３段階で徐々に大きくなっており、最終段側の幅は初段と２段の間に対して約１.９倍大きくなっている。
【００７２】
動翼の植込み部は静翼に対応する部分に比較して直径が大きくなっており、その幅は動翼の翼部長さの大きい程その植込み幅は大きくなっている。その幅の動翼の翼部長さに対する比率は初段から最終段で０.１５〜０.１９であり、初段から最終段になるに従って段階的に小さくなっている。
【００７３】
また、各静翼に対応する部分のロータシャフトの幅は初段と２段目との間から最終段とその手前との間までの各段で段階的に大きくなっている。その幅の動翼の翼部長さに対する比率は０.２５〜１.２５で上流側から下流側になるに従って小さくなっている。
【００７４】
低圧タービンはタンデムに２台連結され、その合計の軸受間距離は約１８.３ｍ であり、低圧タービンの最終段動翼の翼部長さに対するタンデムに結合した２台の前記低圧タービンの軸受間距離の合計の比が１６.７ である。
【００７５】
本実施例は、高圧蒸気タービン及び中圧蒸気タービンへの蒸気入口温度610 ℃，２基の低圧蒸気タービンへの蒸気入口温度３８５℃とする１０００ＭＷ級大容量発電プラントに対しても同様の構成とすることができる。
【００７６】
（発電プラント）
本実施例における発電プラントは主として石炭専焼ボイラ， 高圧タービン，中圧タービン，低圧タービン２台，復水器，復水ポンプ，低圧給水加熱器系統，脱気器，昇圧ポンプ，給水ポンプ，高圧給水加熱器系統などより構成されている。ボイラで発生した超高温高圧蒸気は高圧タービンに入り動力を発生させたのち再びボイラにて再熱されて中圧タービンへ入り動力を発生させる。この中圧タービン排気蒸気は、低圧タービンに入り動力を発生させた後、復水器にて凝縮する。この凝縮液は復水ポンプにて低圧給水加熱器系統， 脱気器へ送られる。この脱気器にて脱気された給水は昇圧ポンプ，給水ポンプにて高圧給水加熱器へ送られ昇温された後、ボイラへ戻る。
【００７７】
ここで、ボイラにおいて給水は節炭器，蒸発器，過熱器を通って高温高圧の蒸気となる。また一方、蒸気を加熱したボイラ燃焼ガスは節炭器を出た後、空気加熱器に入り空気を加熱する。ここで、給水ポンプの駆動には中圧タービンからの抽気蒸気にて作動する給水ポンプ駆動用タービンが用いられている。
【００７８】
このように構成された高温高圧蒸気タービンプラントにおいては、高圧給水加熱器系統を出た給水の温度が従来の火力プラントにおける給水温度よりもはるかに高くなっているため、必然的にボイラ内の節炭器を出た燃焼ガスの温度も従来のボイラに比べてはるかに高くなってくる。このため、このボイラ排ガスからの熱回収をはかりガス温度を低下させないようにする。
【００７９】
１０５０ＭＷ級発電機用ロータシャフトとしてはより高強度のものが用いられる。特に、Ｃ０.１５〜０.３０％，Ｓｉ０.１〜０.３％，Ｍｎ０.５％以下，Ｎｉ３.２５〜４.５％，Ｃｒ２.０５〜３.０％，Ｍｏ0.25 〜０.６０％,Ｖ０.０５〜０.２０％を含有する全焼戻しベーナイト組織を有し、室温引張強さ９３kgｆ／mm²以上、特に１００kgｆ／mm²以上，５０％ＦＡＴＴが０℃以下、特に−２０℃以下とするものが好ましく、２１.２ＫＧ における磁化力が９８５ＡＴ／cm以下とするもの、不純物としてのＰ，Ｓ，Ｓｎ，Ｓｂ，Ａｓの総量を０.０２５％以下，Ｎｉ／Ｃｒ比を２.０以下とするものが好ましい。
【００８０】
高圧，中圧，低圧タービンのいずれのロータシャフトにおいても中心孔が設けられ、この中心孔を通して超音波検査，目視検査及びけい光探傷によって欠陥の有無が検査される。また、外表面から超音波検査により行うことができ、中心孔が無でもよい。
【００８１】
表４は本実施例の発電プラントに係る高圧タービン，中圧タービン及び低圧タービンの主要部に用いた材料の化学組成（重量％）を示す。本実施例においては、高圧部及び中圧部の高温部を全部フェライト系の結晶構造を有する熱膨張係数約１２×１０^-6／℃のものにしたので、熱膨張係数の違いによる問題は全くなかった。
【００８２】
【表４】

【００８３】
高圧タービン及び中圧タービンのロータシャフトは、表4に記載の耐熱鋼を電気炉で３０トン溶解し、カーボン真空脱酸し、金型鋳型に鋳込み、鍛伸して電極棒を作製し、この電極棒として鋳鋼の上部から下部に溶解するようにエレクトロスラグ再溶解し、ロータ形状（直径１０５０mm，長さ３７００mm）に鍛伸して成型した。この鍛伸は、鍛造割れを防ぐために、１１５０℃以下の温度で行った。またこの鍛鋼を焼鈍熱処理後、１０５０℃に加熱し水噴霧冷却焼入れ処理， ５７０℃及び６９０℃で２回焼戻しを行い、最終形状に切削加工によって得られるものである。高圧タービンにおいてはエレクトロスラグ鋼塊の上部側を初段翼側にし、下部を最終段側にするようにした。いずれのロータシャフトも中心孔を有しており、不純物を低下させることにより中心孔を無くすことができる。そして、Ａｌは０．００４％であり、Ｎｉ/Ｃｏ比は０．０４である。本実施例のロータシャフト中心部の６５０℃の１０³ｈ、１０⁴ｈおよび１０⁵ｈのクリープ破断強度は表１のＮｏ．２，３と同等であった。特に、長時間側で高い強度を示すものであった。
【００８４】
更に、このロータシャフトの中心部を調査した結果、高圧，中圧及び後述する高中圧タービンロータに要求される特性（６２５℃，１０⁵ｈ強度≧１０kgｆ／mm²，２０℃衝撃吸収エネルギー≧１.５kgｆ−ｍ)を十分満足することが確認された。これにより、６２０℃以上の蒸気中で使用可能な蒸気タービンロータが製造できることが実証された。
【００８５】
高圧部及び中圧部のブレード及びノズルは、同じく表4に記載の耐熱鋼を真空アーク溶解炉で溶解し、ブレード及びノズル素材形状（幅１５０mm，高さ５０mm，長さ１０００mm）に鍛伸して成型した。この鍛伸は、鍛造割れを防ぐために、１１５０℃以下の温度で行った。またこの鍛鋼を１０５０℃に加熱し油焼入れ処理，６９０℃で焼戻しを行い、次いで所定形状に切削加工したものである。
【００８６】
またこのブレードの特性を調査した結果、高圧，中圧タービンの初段ブレードに要求される特性（６２５℃，１０⁵ｈ強度≧１５kgｆ／mm²）を十分満足することが確認された。これにより、６２０℃以上の蒸気中で使用可能な蒸気タービンブレードが製造できることが実証された。
【００８７】
高圧部及び中圧部の内部ケーシング，主蒸気止め弁ケーシング及び蒸気加減弁ケーシングは、表4に記載の耐熱鋳鋼を電気炉で溶解し、とりべ精錬後、砂型鋳型に鋳込み作製した。鋳込み前に、十分な精錬及び脱酸を行うことにより、引け巣等の鋳造欠陥のないものができた。このケーシング材を用いた溶接性評価は、ＪＩＳ Ｚ３１５８に準じて行った。予熱，パス間及び後熱開始温度は２００℃に、後熱処理は４００℃×３０分にした。本発明材には溶接割れが認められず、溶接性が良好であった。
【００８８】
さらにこのケーシングの特性を調査した結果、高圧，中圧，高中圧タービンケーシングに要求される特性（６２５℃，１０⁵ｈ強度≧１０kgｆ／mm²，２０℃衝撃吸収エネルギー≧１kgｆ−ｍ）を十分満足することと溶接可能であることが確認された。これにより、６２０℃以上の蒸気中で使用可能な蒸気タービンケーシングが製造できることが実証された。
【００８９】
本実施例においては、高圧及び中圧タービンロータシャフトのジャーナル部にＣｒ−Ｍｏ低合金鋼を肉盛溶接し、軸受特性を改善させた。供試溶接棒として表５に示す（重量％）被覆アーク溶接棒(直径４.０ｍｍ）を用い、肉盛溶接を表６に示す各層ごとに使用溶接棒を組合せて、８層の溶接を行った。各層の厚さは３〜４mmであり、全厚さは約２８mmであり、表面を約５mm研削した。溶接施工条件は、予熱，パス間，応力除去焼鈍（ＳＲ）開始温度が２５０〜３５０℃及びＳＲ処理条件は６３０℃×３６時間保持である。
【００９０】
【表５】

【００９１】
【表６】

【００９２】
溶接部の性能を確認するために板材に同様に肉盛溶接し、１６０゜の側曲げ試験を行ったが、溶接部に割れは認められず、更に、回転による軸受摺動試験においても、軸受に対する悪影響もなく、耐酸化性に対しても優れたものであった。
【００９３】
〔実施例３〕
表７は蒸気温度６００℃，定格出力７００ＭＷ蒸気タービン発電プラントの主な仕様である。本実施例は、タンデムコンパウンドダブルフロー型、低圧タービンにおける最終段翼長が４６インチであり、ＨＰ（高圧）・ＩＰ（中圧）一体型及びＬＰ１台（Ｃ）又は２台（Ｄ）で３０００rpm の回転数を有し、高圧部及び低圧部においては前述の表４に示す主な材料によって構成される。高圧部(ＨＰ)の蒸気温度は６００℃，２５０kgｆ／cm² の圧力であり、中圧部（ＩＰ）の蒸気温度は６００℃に再熱器によって加熱され、４５〜６５kgｆ／cm² の圧力で運転される。低圧部（ＬＰ）は蒸気温度は４００℃で入り、１００℃以下，７２２mmＨｇの真空で復水器に送られる。
【００９４】
本実施例における高中圧一体タービン及び２台の低圧タービンをタンデムに備えた蒸気タービン発電プラント（Ｄ）は、軸受間距離が約２２.７ｍであり、その低圧タービンの最終段動翼の翼部長さ（１１６８mm）に対して１９.４倍 であり、また発電プラントの定格出力７００ＭＷの１ＭＷ当たりの軸受間距離の合計距離が３２．４ｍｍである。更に、本実施例における高中圧一体タービン及び１台の低圧タービンを備えた蒸気タービン発電プラント（Ｃ）は、軸受間距離が約１４.７ｍであり、低圧タービンの最終段動翼の翼部長さ（１１６８mm) に対して１２.６倍 であり、定格出力１ＭＷ当たり２１.０ｍｍである。
【００９５】
【表７】

【００９６】
図３は高圧中圧一体型蒸気タービンの断面構成図である。高圧側蒸気タービンは高圧内部車室１８とその外側の高圧外部車室１９内に高圧動翼１６を植設した高中圧車軸（高中圧一体型ロータシャフト）３３が設けられる。高温高圧の蒸気は前述のボイラによって得られ、主蒸気管を通って、主蒸気入口を構成するフランジ，エルボ２５より主蒸気入口２８を通り、ノズルボックス３８より初段の動翼に導かれる。蒸気はロータシャフトの中央側より入り、軸受側に流れる構造を有する。動翼は図中左側の高圧側に８段及び(図中右側約半分の)中圧側に６段設けられる。これらの動翼に対応して各々静翼が設けられる。動翼は鞍型又はゲタ型，ダブティル型式，ダブルティノン，高圧側初段翼長約４０mm，中圧側初段翼長が１００mmである。軸受４３間の長さは約６.７ｍ 及び静翼部に対応する部分で最も小さい部分の直径は約７４０mm であり、直径に対する長さの比は約９.０である。
【００９７】
本実施例の高中圧タービン及び低圧タービンの主要部に前述の表４に示す化学組成（重量％）を有する材料を用いた。高中圧一体型ロータシャフトには実施例２に記載ものものを用いた。又、高中圧一体型ロータシャフトは中心孔を有しているが、特に、Ｐ０.０１０％以下，Ｓ０.００５％以下,Ａｓ０.００５％以下,Ｓｎ０.００５％以下，Ｓｂ０.００３％ 以下とする高純化によりその中心孔をなくすことができる。更に、軸受部へのＣｒ−Ｍｏ低合金鋼の肉盛溶接層も同様に形成した。又、その発電機シャフトとしては実施例２と同様により高強度のものが用いられる。
【００９８】
高圧側のロータシャフトは初段と最終段の動翼植込み付根部分の幅が初段が最も広く、２段目〜７段目がそれより小さく、初段の０.４０〜０.５６倍でいずれも同等の大きさであり、最終段が初段と２〜７段目の大きさの間にあり、初段の０.４６〜０.６２倍の大きさである。
【００９９】
高圧側における動翼の翼部の長さは初段が３５〜５０mm、２段目から最終段になるに従って各段で長くなっており、特に蒸気タービンの出力によって２段から最終段までの長さが５０〜１５０mmの範囲内であり、段数は７〜１２段の範囲内にあり、各段の翼部の長さは下流側が上流側に対して隣り合う長さで１.０５〜１.３５倍の範囲内で長くなっているとともに、下流側でその比率が徐々に大きくなっている。
【０１００】
中圧側蒸気タービンは高圧側蒸気タービンより排出された蒸気を再度６００℃に再熱器によって加熱された蒸気によって高圧蒸気タービンと共に発電機を回転させるもので、３０００rpm の回転数によって回転される。中圧側タービンは高圧側タービンと同様に中圧内部第２車室２１と中圧外部車室２２とを有し、中圧動翼１７と対抗して静翼が設けられる。中圧動翼１７は６段である。初段翼長さ約１３０mm，最終段翼長さ約２６０mmである。ダブティルは逆クリ型である。
【０１０１】
中圧側のロータシャフトは動翼植込み付根部の軸方向幅が初段が最も大きく、２段目がそれより小さく、３〜５段目が２段目より小さくいずれも同じで、最終段の幅は３〜５段目と２段目の間の大きさで、初段の０.４８〜0.64倍である。初段は２段目の１.１〜１.５倍である。
【０１０２】
中圧側における動翼の翼部の長さは初段から最終段になるに従って各段で長くなっており、蒸気タービンの出力によって初段から最終段までの長さが９０〜３５０mm、段数が６〜９段の範囲内にあり、各段の翼部の長さは下流側が上流側に対して隣り合う長さで１.１０〜１.２５の割合で長くなっている。
【０１０３】
動翼の植込み部は静翼に対応する部分に比較して直径が大きくなっており、その幅は動翼の翼部長さと位置に関係する。その幅の動翼の翼部長さに対する比率は初段が最も大きく、１.３５〜１.８０倍，２段目が０.８８〜１.１８倍，３〜６段目が最終段になるに従って小さくなっており、０.４０〜０.６５倍である。
【０１０４】
本実施例のタンデムに結合した２台の低圧タービンを備えた蒸気タービン発電プラント用高中圧一体タービンは、軸受間距離が約６.７ｍ であり、低圧タービンの最終段動翼の翼部長さ（１１６８mm)に対して５.７倍であり、また定格出力１ＭＷ当たり９．５７ｍｍである。
【０１０５】
本実施例においても、高中圧一体型蒸気タービンロータシャフトの軸受部には実施例２と同様に低合金鋼の肉盛溶接層が設けられる。
【０１０６】
図４は低圧タービンの断面図である。低圧タービンは１基又はタンデムに２基あり、いずれも高中圧タービンにタンデムに結合される。動翼４１は左右に６段あり、左右ほぼ対称になっており、また動翼に対応して静翼４２が設けられる。最終段の動翼には長さが４６インチであり、実施例２と同様にＴｉ基合金又は高強度１２％Ｃｒ鋼が用いられる。ロータシャフト４４は実施例２と同様にスーパークリーン材の全焼戻しベーナイト組織を有する鍛鋼が用いられる。最終段とその前段以外の動翼及び静翼にはいずれもＭｏを０.１％ 含有する１２％Ｃｒ鋼が用いられる。内外部ケーシング材にはＣ０.２５％ の前述の組成の鋳鋼が用いられる。本実施例における軸受４３での中心間距離は８ｍで、静翼部に対応するロータシャフトの直径は約800 mm，動翼植込み部での直径は各段同じである。静翼部に対応するロータシャフト直径に対する軸受中心間の距離は１０倍である。
【０１０７】
本実施例の４６インチ翼には、Ｃ０．２３％、Ｓｉ０．０６％、Ｍｎ０．１５％、Ｃｒ１１．４％、Ｎｉ２．６５％、Ｍｏ３．１０％、Ｖ０．２５％、Ｎｂ０．１１％、Ｎ０．０６％を含むマルテンサイト鋼を用い、焼入れ及び焼戻しを行った。このものの引張強さが１４５ｋｇ/ｍｍ²、Ｖノッチ衝撃値が６．２ｋｇ―ｍ/ｃｍ²であった。
【０１０８】
ロータシャフトには動翼の植込み部が設けられ、最終段のダブティルにはフォーク型の他に逆クリスマスツリー型も同様に用いられる。
【０１０９】
低圧タービンは動翼植込み付根部の軸方向の幅が初段が最も小さく、下流側に従って２，３段が同等、４段，５段が同等で４段階で徐々に大きくなっており、最終段の幅は初段の幅に比べ６.２〜７.０倍と大きくなっている。２，３段は初段の１.１５〜１.４０倍、４，５段が２，３段の２.２〜２.６倍、最終段が４，５段の２.８〜３.２倍となっている。付根部の幅は末広がりの延長線とロータシャフトの直径とを結ぶ点で示す。
【０１１０】
本実施例における動翼の翼部長さは初段の４″から４６″の最終段になるに従って各段で長くなっており、最大で８段で、各段の翼部長さは下流側が上流側に対して隣り合う長さで１.２〜１.９倍の範囲内で徐々に長くなっている。
【０１１１】
動翼の植込み付根部は静翼に対応する部分に比較して直径が大きく末広がりになっており、その幅は動翼の翼部長さの大きい程その植込み幅は大きくなっている。その幅の動翼の翼部長さに対する比率は初段から最終段の前までが０.３０ 〜１.５であり、その比率は初段から最終段の前になるに従って徐々に小さくな っており、後段の比率はその１つ手前のものより０.１５〜０.４０の範囲内で徐々に小さくなっている。最終段は０.５０〜０.６５の比率である。
【０１１２】
本実施例における最終段動翼における平均直径は、３０００rpm 、４３″翼で２５９０mm、３６００rpm 、３６″翼で２１６０mm、３０００rpm 、４６″翼で２６６５mm、３６００rpm 、３８″翼で２２２０mmとした。
【０１１３】
本実施例におけるエロージョンシールドは前述と同様にステライト合金板が電子ビーム溶接又はＴＩＧ溶接によって接合される。エロージョンシールドは湿り蒸気が直接当たる表側とその裏側の２個所でエロージョンシールド部材の全長に渡って溶接される。表側は幅が裏側より大きく、上下端部も溶接される。
【０１１４】
本実施例における高温高圧蒸気タービン発電プラントは主としてボイラ，高中圧タービン，低圧タービン，復水器，復水ポンプ，低圧給水加熱器系統，脱気器，昇圧ポンプ，給水ポンプ，高圧給水加熱器系統などより構成される。すなわち、ボイラで発生した超高温高圧蒸気は高圧側タービンに入り動力を発生させたのち再びボイラにて再熱されて中圧側タービンへ入り動力を発生させる。この高中圧タービン排気蒸気は、低圧タービンに入り動力を発生させた後、復水器にて凝縮する。この凝縮液は復水ポンプにて低圧給水加熱器系統，脱気器へ送られる。この脱気器にて脱気された給水は昇圧ポンプ，給水ポンプにて高圧給水加熱器へ送られ昇温された後、ボイラへ戻る。
【０１１５】
ここで、ボイラにおいて給水は節炭器，蒸発器，過熱器を通って高温高圧の蒸気となる。また一方、蒸気を加熱したボイラ燃焼ガスは節炭器を出た後、空気加熱器に入り空気を加熱する。ここで、給水ポンプの駆動には中圧タービンからの抽気蒸気にて作動する給水ポンプ駆動用タービンが用いられている。
【０１１６】
このように構成された高温高圧蒸気タービンプラントにおいては、高圧給水加熱器系統を出た給水の温度が従来の火力プラントにおける給水温度よりもはるかに高くなっているため、必然的にボイラ内の節炭器を出た燃焼ガスの温度も従来のボイラに比べてはるかに高くなってくる。このため、このボイラ排ガスからの熱回収をはかりガス温度を低下させないようにする。
【０１１７】
本実施例の他、高中圧蒸気タービンの蒸気入口温度６１０℃以上，低圧蒸気タービンへの蒸気入口温度約４００℃及び出口温度が約６０℃とする１０００ＭＷ級大容量発電プラントに対しても同様の構成とすることができる。尚、蒸気温度として、５９３℃又は６３０℃においても本実施例の材料構成及び構造をそのまま使用できる。
【０１１８】
【発明の効果】
本発明によれば、６００℃以上及び５万時間以上の特定の温度及び長時間側において高温長時間側強度の優れた蒸気タービン用ロータシャフトが得られ、それを高圧、中圧、高中圧蒸気タービンを用いることにより、特に超々臨界圧蒸気タービンに適用すれば、蒸気タービンの蒸気温度を６５０℃以上に高めることが可能になり、蒸気タービン発電プラントの熱効率の向上に顕著な効果が得られる。
【図面の簡単な説明】
【図１】高圧蒸気タービン及び中圧蒸気タービンを連結した断面図。
【図２】低圧蒸気タービンの断面図。
【図３】高中圧蒸気タービンの断面図。
【図４】低圧蒸気タービンの断面図。
【符号の説明】
１…第１軸受、２…第２軸受、３…第３軸受、４…第４軸受、５…推力軸受、１０…第１シャフトパッキン、１１…第２シャフトパッキン、１２…第３シャフトパッキン、１３…第４シャフトパッキン、１４…高圧隔板、１５…中圧隔板、１６…高圧動翼、１７…中圧動翼、１８…高圧内部車室、１９…高圧外部車室、２０…中圧内部第１車室、２１…中圧内部第２車室、２２…中圧外部車室、２３…高圧車軸、２４…中圧車軸、２５…フランジ，エルボ、２６…前側軸受箱、２８…主蒸気入口、２９…再熱蒸気入口、３０…高圧蒸気排気口、３１…気筒連絡管、３３…高中圧車軸、３８…ノズルボックス（高圧第１段）、３９…推力軸受摩耗遮断装置、４０…暖機蒸気入口、４１…動翼、４２…静翼、４３…軸受、４４…ロータシャフト。[0001]
BACKGROUND OF THE INVENTION
  The present invention is a novel method for producing a rotor shaft for a steam turbine.Related to,In particularSoManufacturing methodRotor shaft obtained byThe highIntegrated steam turbine with high pressure, medium pressure, and high pressureCan be applied to,MoreThatSteamingAir turbine power plantAsEspecially for ultra-supercritical thermal power plantsApplicableIs.
[0002]
[Prior art]
In recent years, high-temperature and high-pressure has been observed in thermal power plants from the viewpoint of improving efficiency, and the steam temperature of steam turbines is currently targeted at 600 ° C., and finally 650 ° C. In order to increase the steam temperature, a heat-resistant material having a higher temperature strength than that of the conventionally used ferritic heat-resistant steel is required. Some austenitic heat-resistant alloys have excellent temperature resistance, but there is a problem that thermal fatigue strength is inferior due to a large coefficient of thermal expansion.
[0003]
For this reason, examples of new ferritic heat resistant steels with improved high-temperature strength include JP-A-4-147948, JP-A-9-296258 and JP-B-8-30249. JP-A-7-233704 and JP-A-11-93603 are known as steam turbine power plants.
[0004]
[Problems to be solved by the invention]
However, in order to achieve the ultimate steam temperature of 650 ° C., these proposed alloys contain a lot of W and Co, so that they form brittle intermetallic compounds on the long time side, and long time creep rupture strength. Therefore, it has been desired to develop a ferritic heat-resisting steel that is still insufficient and has high strength at high temperature and stable strength for a long time.
[0005]
  The object of the present invention is to produce a rotor shaft for a steam turbine with excellent high temperature and long-side strength at a specific temperature and long-time side of 600 ° C. or higher and 50,000 hours or longerThe lawIt is to provide.
[0006]
[Means for Solving the Problems]
  In the present invention, by weight, C 0.05 to 0.20%, Si 0.2% or less, Mn 0.01 to 1.5%, Ni 0.01 to 0.3%, Cr 9.0 to 13.0%, Mo0. 0.05 to 0.5%, W 0.5 to 5.0%, V 0.05 to 0.30%, Nb 0.01 to 0.20%, Co 1.0 to 2.0%, N 0.01 to 0.0. 1%, B 0.001 to 0.030% and Al 0.0005 to 0.006%, (Ni / Co) ratio is 0.00.1 or moreIt is made of martensite steel consisting of the remaining Fe and inevitable impurities, and is tempered after quenching so that the cooling rate in the center hole is 50 to 600 ° C./h. It is in the manufacturing method of the rotor shaft.
[0007]
  The present inventionInThe martensitic steel mentioned aboveof(Ni / Co) ratioIs0.09 or higherBelow ispreferable.
[0009]
  The present inventionThe aboveMartensite steelof650 ° C, 100,000 hour creep rupture strength is 10.5kg / mm²That's itIs preferable.
[0010]
  The present invention includes a rotor shaft, a moving blade implanted in the rotor shaft, a stationary blade that guides the inflow of water vapor into the moving blade, and an inner casing that holds the stationary blade.,A high-pressure steam turbine in which the moving blade is at least five stages on one side and the first stage is planted in a double flow structure in the center, and the rotor blade has six or more stages symmetrically in the left and right, and the first stage is planted in the center of the rotor shaft. An intermediate-pressure steam turbine having a double-flow structure or a high-pressure turbine from which high-temperature and high-pressure steam flows from the central portion of the rotor shaft is heated to the intermediate-pressure turbine from the central portion of the rotor shaft. In any one of the high and medium pressure steam turbines that flow in and the high pressure turbine blades have six or more stages and the intermediate pressure turbine blades have five or more stages, the rotor shaft is obtained by the above-described manufacturing method.BeIt is preferable.
[0011]
C ensures hardenability and M during the tempering process_{twenty three}C₆ It is an indispensable element for precipitating type carbides and increasing the high-temperature strength. At least 0.05% is required, but if it exceeds 0.20%, M_{twenty three}C₆ Since the type carbide is excessively precipitated and the degree of matrix is lowered and the high-temperature strength on the long time side is impaired, it is limited to 0.05 to 0.20%. Preferably, the content is 0.1 to 0.15%.
[0012]
Mn suppresses the formation of δ ferrite, and M_{twenty three}C₆ At least 0.01% is necessary as an element for promoting precipitation of type carbide, but if it exceeds 1.5%, the oxidation resistance deteriorates, so the content is limited to 0.01 to 1.5%. Desirably, it is 0.1 to 0.7%. More preferably, it is 0.35 to 0.65%.
[0013]
  Ni is an element that suppresses the formation of δ-ferrite and imparts toughness, and needs to be at least 0.01%, and the ratio of (Ni / Co) between Co and Ni is set to 0.00.1 or moreIt is the following. However, Ni has a (Ni / Co) ratio of 0. 0.1 or moreIn the lower case, if it exceeds 0.3%, the long-term creep rupture strength of 600 ° C. or more and 50,000 hours or more is lowered, so the upper limit is made 0.3%, preferably 0.2% or less, more desirably 0.15%, particularly 0.01 to 0.06% is preferable. In particular, lowering with Co improves long-term creep rupture strength of 100,000 hours or more.
[0014]
Cr imparts oxidation resistance and M_{twenty three}C₆ It is an indispensable element for increasing the high temperature strength by precipitating type carbide, and at least 9% is necessary. However, if it exceeds 13%, δ ferrite is generated, and the high temperature strength and toughness are lowered. Limited to 0.0%. Desirably, it is 9.5 to 11.5%, more desirably 10.0 to 11.0%.
[0015]
  Mo isM ₂₃ C ₆ It has the effect of promoting fine precipitation of type carbides and preventing agglomeration, and is therefore effective in maintaining high temperature strength for a long time, and at least 0.05% is necessary.0 . 5If it exceeds 50%, δ ferrite is easily generated.0 . 5Limited to%. YoMore preferably, it is 0.1 to 0.3%.
[0016]
W is M more than Mo_{twenty three}C₆ It has a strong effect of suppressing the coarsening and coarsening of type carbides, and is effective in improving high-temperature strength because it strengthens the matrix in solid solution. At least 0.5% is necessary, but if it exceeds 5.0%, δ ferrite and A Laves phase is likely to be generated, and conversely, high temperature strength is reduced. Preferably, it is 1.0 to 3.0%.
[0017]
V is effective in increasing the high temperature strength by precipitating the carbonitride of V. At least 0.05% is required, but if it exceeds 0.3%, carbon is excessively fixed, and M_{twenty three}C₆ Since the amount of precipitation of the type carbide is reduced and the high-temperature strength is lowered, the content is limited to 0.05 to 0.3%. Desirably, it is 0.10 to 0.30%.
[0018]
At least one of Nb and Ta is used to generate NbC and TaC to help refine the crystal grains, and partly dissolves during quenching to precipitate NbC and TaC during the tempering process, thereby increasing high-temperature strength. At least 0.01% is necessary, but if it exceeds 0.20%, carbon is excessively fixed like V and M_{twenty three}C₆ The amount of precipitation of the type carbide is reduced and the high temperature strength is lowered, so the content is limited to 0.01 to 0.20%. Preferably, it is 0.04 to 0.13%.
[0019]
  Co is an important element that distinguishes and characterizes the present invention from the conventional invention. In the present invention, the ratio of (Ni / Co) to Ni is set to 0.1 or more0.1 or moreWith respect to the lower ratio, the addition of Co 1.0 to 2.0% remarkably improves the long-side high temperature strength of 600 ° C. or more and 50,000 hours or more. This is considered to be due to the interaction with W and is a characteristic phenomenon in the alloy of the present invention containing 0.5% or more of W.or, Co addition exceeding 2.0% is not preferable because the side strength decreases for a long time. Desirably, it is 1.1 to 1.8%. Furthermore, Co is improved together with Ni to improve the creep rupture strength. Both are austenite stabilizing elements, and also promote precipitation and make the long-side unstable. Both are made low, and (Ni / Co) ratio is 0.1 or moreShow the best long-term stability below, especially, Yo0.09 or less is preferable. However, if these are too low, delta ferrite is produced, so C is increased.
[0020]
N has the effect of increasing the high temperature strength by the IS effect (interaction between the interstitial solid solution element and the substitutional solid solution element) in combination with Mo and W in the form of a solid solution in which V nitride is precipitated. At least 0.01% is necessary, but if it exceeds 0.1%, the ductility is lowered, so the content is limited to 0.01 to 0.1%. Preferably, the content is 0.01 to 0.04%.
[0021]
  Si promotes the formation of Laves phase and also reduces ductility due to grain boundary segregation, etc.0 . 2% or less, preferablyLimit to 0.15% or less.ThanDesirably, it is 0.10% or less. However, when Si is added in a very small amount of 0.03% or more as a deoxidizer, good high temperature characteristics can be obtained from the relationship with Al deoxidation described later.
[0022]
Al is added in an amount of 0.0005% or more as a deoxidizer and a grain refiner. However, Al is a strong nitride-forming element. By fixing nitrogen that works effectively for creep, especially when it exceeds 0.006%, long-term creep of 50,000 hours or more in a high temperature range of 625 ° C. to 700 ° C. Has the effect of reducing strength. Further, Al promotes the precipitation of the Laves phase, which is a brittle intermetallic compound mainly composed of W, invites the precipitation to the crystal grain boundary, and lowers the creep rupture strength on the long time side. In particular, in the case of extreme grain refinement, Laves phase continuously precipitates at the grain boundaries. Therefore, the upper limit is set to 0.006%. More preferably, it is 0.001 to 0.004%. In particular, the effect is large on the high W side with W of 1.5 to 3.0%.
[0023]
B is the grain boundary strengthening effect and M_{twenty three}C₆ Solid solution inside, M_{twenty three}C₆ There is an effect of increasing the high temperature strength by preventing the agglomeration and coarsening of the type carbide, and it is effective to add at least 0.001%, but if it exceeds 0.030%, the weldability and forgeability are impaired, so 0.001 to Limited to 0.030%. Preferably, it is 0.005 to 0.025%.
[0024]
The chromium equivalent determined by the following formula is preferably 4 to 10.5, particularly preferably 6.5 to 9.5.
Chromium equivalent = -40C (%)-30N (%)-2Mn (%)-4Ni (%) + Cr (%) + 6Si (%) + 4Mo (%) + 1.5W (%) + 11V (%) + 5Nb (%) + 2 .5Ta (%)-2Co (%)-2Co (%)
The rotor shaft of the present invention is obtained by casting an ingot by vacuum melting, vacuum C deoxidation, ESR melting, forging, heating at 900 to 1150 ° C, quenching by cooling at 50 to 600 ° C / h in the center hole, Next, primary tempering is performed at 500 to 620 ° C and secondary tempering at 600 to 750 ° C at a higher temperature.
[0025]
  The present invention relates to a steam turbine power plant in which a high-pressure turbine, an intermediate-pressure turbine, and one or two low-pressure turbines are connected in tandem or cross, or a high-pressure turbine, a low-pressure turbine, a generator, and an intermediate-pressure turbine, a low-pressure turbine, and a generator. In a steam turbine power plant in which both are coupled in tandem, the rotor shaft of at least one of the high-pressure turbine and the intermediate-pressure turbine is in front.As statedIt is preferably obtained by the described production method.
[0026]
  In the steam turbine power plant according to the present invention, the high-pressure turbine and the medium-pressure turbine or the high-medium-pressure turbine have steam inlet temperatures of 593 to 660 ° C. (593 to 605 ° C., 610 to 620 ° C., 620 to 630 ° C.). 630 to 640 ° C), and the pressure is 250 kgf / cm.²Or more (preferably 246 to 316 kgf / cm²) Or 170-200 kgf / cm² Wherein the rotor shaft is obtained by the above-described manufacturing method, and 10 at a temperature corresponding to each steam temperature.^Five Time creep rupture strength is 10 kgf / mm² Above (preferably 10.5kgf / mm² more than)And at least the first stage of the rotor blade and the stationary blade at a temperature corresponding to each steam temperature. ^Five Time creep rupture strength is preferably 17 kg f / mm ² more thanA high-strength martensitic steel having a total tempered martensite structure containing 9 to 13 wt% (preferably 10.5 to 11.5 wt%) of Cr is preferable. The low-pressure turbine preferably has a steam inlet temperature to the first stage blade of 350 to 400 ° C. Furthermore, it is preferable that the first stage, the second stage, or the third stage of the rotor blade is made of a Ni-based alloy.
[0027]
(1) In the high-pressure steam turbine according to the present invention, the moving blade has 7 stages or more, preferably 9 stages or more, preferably 9 to 12 stages, the first stage is a double flow, and the rotor shaft has a bearing center distance ( L) is preferably 5000 mm or more (preferably 5100 to 6500 mm). The blade length is preferably 25 to 180 mm from the first stage to the last stage.
[0028]
(2) The intermediate pressure steam turbine according to the present invention has a double flow structure in which the moving blades have 6 or more stages, preferably 6 to 9 stages symmetrically, and the first stage is implanted in the center of the rotor shaft. And the rotor shaft preferably has a bearing center distance (L) of 5000 mm or more (preferably 5100 to 6500 mm). The wing length is preferably 60 to 300 mm.
[0029]
(3) In the high and medium pressure integrated steam turbine according to the present invention, the rotor blade on the high pressure side has 7 stages or more, preferably 8 stages or more, and the medium pressure side rotor blade has 5 stages or more, preferably 6 stages or more, and the rotor shaft The bearing center distance (L) is preferably 6000 mm or more (preferably 6100 to 7000 mm). The blade length is preferably 25 to 200 mm on the high pressure side and 100 to 350 mm on the medium pressure portion.
[0030]
(4) The rotor shaft of the high-pressure, medium-pressure and high-medium-pressure turbine according to the present invention has the above-mentioned Cr as a fully tempered martensite structure having the above-mentioned composition in order to obtain high high-temperature strength, low-temperature toughness and high fatigue strength. It is preferable to adjust the component to an equivalent weight of 4-8.
[0031]
(5) The high-pressure, intermediate-pressure or high-medium-pressure integrated steam turbine rotor shaft according to the present invention is preferably formed with a built-up weld layer of Cr-Mo low alloy steel having high bearing characteristics in its journal portion. Preferably, the build-up weld layer having any number of layers from 10 to 10 is formed, and the Cr content of the welding material from the first layer to any one of the second to fourth layers is sequentially reduced. At the same time, welding is performed using a welding material made of steel having the same Cr amount, and the Cr amount of the welding material used for welding the first layer is reduced by about 2 to 6% by weight from the Cr amount of the base material. Thereafter, the Cr content of the weld layer is 0.5 to 3% by weight (preferably 1 to 2.5% by weight).
[0032]
In the present invention, overlay welding is preferable for improving the bearing characteristics of the journal part because it is the safest, but it is assumed that a sleeve made of a low alloy steel having a Cr content of 1 to 3% is fit and fitted. It can also be a structure.
[0033]
Three or more layers are preferable for increasing the number of weld layers and gradually reducing the Cr content, and even if ten or more layers are welded, no further effect can be obtained. As an example, a final finish requires a thickness of about 18 mm. In order to form such a thickness, at least five overlay welding layers are preferable even if the final finishing allowance by cutting is excluded. It is preferable that the third and subsequent layers mainly have a tempered bainite structure and have carbides precipitated. In particular, the composition of the weld layer after the fourth layer is C0.01-0.1%, Si0.3-1%, Mn0.3-1.5%, Cr0.5-3%, Mo0.1 by weight. Those comprising ˜1.5% and the balance being Fe are preferred.
[0034]
(6) High pressure turbine of the present invention, medium pressure turbine and high and medium pressure turbine inner casing adjustable valve valve box, combined reheat valve valve box, main steam lead pipe, main steam inlet pipe, reheat inlet pipe, high pressure turbine nozzle box, The martensitic heat-resistant steel constituting the first stage diaphragm of the medium pressure turbine, the high pressure turbine main steam inlet flange, the elbow, and the main steam stop valve is preferable.
[0035]
250kgf / cm² The above ultra-supercritical turbine high-pressure, medium-pressure or high-medium pressure inner casing, main steam stop valve and control valve casing are^Fiveh Creep rupture strength 9 kgf / mm²Thus, room temperature impact absorption energy of 1 kgf-m or more is preferable.
[0036]
(7) As an inner casing material of the high-pressure turbine, intermediate-pressure turbine, and high-medium-pressure turbine of the present invention, 10 at a temperature corresponding to each steam temperature.^FiveTime creep rupture strength is 10kgf / mm²Above (preferably 10.5 kgf / mm² It is made of martensitic cast steel containing Cr 8 to 9.5 wt%. The specific composition is C 0.06 to 0.16% (preferably 0.09 to 0.14%), N 0.01 to 0.1% (preferably 0.02 to 0.06%) by weight. , Mn 1% or less (preferably 0.4 to 0.7%), Si added or 0.5% or less (preferably 0.1 to 0.4%), V 0.05 to 0.35% (preferably 0.15 to 0.25%), Nb 0.15% or less (preferably 0.02 to 0.1%), Ni 0.2 to 1% (preferably 0.4 to 0.8%), Cr 8 to 12 % (Preferably 8 to 10%, more preferably 8.5 to 9.5%), W1 to 3.5%, Mo 1.5% or less (preferably 0.4 to 0.8%) and the balance Fe. The martensitic cast steel is preferred. The amount of W is 1.0 to 1.5% at 620 ° C, 1.6 to 2.0% at 630 ° C, 2.1 to 2.5% at 640 ° C, and 2.6 to 3.3 for 650 ° C. At 0% and 660 ° C., 3.1 to 3.5% is preferable.
[0037]
Addition of Ta, Ti and Zr has an effect of increasing toughness, and a sufficient effect can be obtained by adding Ta alone or a combination of Ta 0.15% or less, Ti 0.1% or less and Zr 0.1% or less. When Ta is added in an amount of 0.1% or more, the addition of Nb can be omitted.
[0038]
(8) The low-pressure steam turbine according to the present invention has a rotational speed of 3000 rpm or 3600 rpm, and the moving blades have 5 or more stages symmetrically, preferably 6 or more stages, more preferably 8 to 10 stages, It is a double flow structure in which the first stage is implanted in the center of the rotor shaft, and the rotor shaft preferably has a bearing center distance (L) of 6500 mm or more (preferably 6600 to 7500 mm). The wing length is preferably 90 mm or more in the first stage, and the last stage has the length described above. The rotor shaft has a 0.02% proof stress at the center of the rotor shaft at room temperature of 80 kg / mm.² Above, 0.2% proof stress is 87.5kg / mm² Above or tensile strength is 92kg / mm² Above, FATT is -5 ° C or lower or 20 ° C V notch impact value is 10kg · m / cm²It is preferable to consist of the above bainitic steel.
[0039]
The final stage blade of the low-pressure steam turbine uses a Ti-based alloy or 17-4PH, 12% Cr martensitic steel, and has high tensile strength to withstand high centrifugal force and vibration stress due to high-speed rotation. Cycle fatigue strength must be high. The Ti-based alloy contains 3 to 8% Al and 3 to 6% V, and is subjected to an aging treatment. In addition, the latter 12% martensitic steel significantly reduces fatigue strength when harmful δ ferrite is present. Therefore, the Cr equivalent calculated by the above-described formula for the total tempered martensite structure is 10 or less, preferably The components are adjusted to 4 to 10 so that the δ ferrite phase is not substantially contained, and as a tempering heat treatment, preferably at 1000 ° C. to 1100 ° C. (preferably 1000 to 1055 ° C.) after melting and forging. Is heated and held for 0.5 to 3 hours and then rapidly cooled to room temperature (especially oil quenching is preferred), then tempered at 540 to 620 ° C., particularly preferably kept at 540 to 570 ° C. for 1 to 6 hours. Two or more tempering heat treatments of primary tempering after cooling to room temperature and secondary tempering after cooling to room temperature after holding at 560 ° C. to 590 ° C., preferably for 1 to 6 hours. Preferably it is. The secondary tempering temperature is preferably higher than the primary tempering temperature, particularly preferably 10 to 30 ° C higher, more preferably 15 to 20 ° C higher. Further, it is preferable to carry out a deep cooling process for cooling to dry ice or liquid nitrogen temperature in order to decompose the retained austenite more completely.
[0040]
In particular, as a 12% martensitic steel, C0.14 to 0.40%, preferably 0.19 to 0.40%, Si 0.5% or less, Mn 1.5% or less, Ni2 to 3.5%, Cr8 ~ 13%, Mo1.5 ~ 4%, one or more of Nb and Ta in total 0.02 ~ 0.3%, V0.05 ~ 0.35% and N0.04 ~ 0.15% Is preferred. More preferred is a combination containing C 0.20 to 0.40% and Mo 1.5 to 3.5% or C 0.14 to 0.19% and Mo 2.0 to 3.5%.
[0041]
The last blade length of the low pressure turbine is 882 mm (35.8 "), 952.5 mm (37.5"), 1016 mm (40 "), 1067 mm (42") and 3000 rpm for 3600 rpm. 1092 mm (43 "), 1168.4 mm (46"), 1219.2 mm (48 "), and 1270 mm (50") are applied.
[0042]
It is preferable that an erosion prevention layer made of a Co-based alloy is provided at the leading edge of the last stage blade. The Co base alloy is preferably joined by electron beam or TIG welding to a plate material having Cr of 25 to 30%, W of 1.5 to 7.0%, and C of 0.5 to 1.5%.
[0043]
In the final stage blade of the low-pressure steam turbine, the inclination in the width direction of the blade portion is substantially parallel to the axial direction of the rotating shaft in the vicinity of the implanted portion, and the blade tip is preferably inclined by 65 to 85 degrees with respect to the axial direction. 70 to 80 degrees is more preferable. Fork type whose wing length is 43 inches or more for 3000 rpm or 37.5 inches or more for 3600 rpm, and 9 or more implantation parts for 43 inches or more and 7 or more for 37.5 inches or more An inverted Christmas tree type having four or more protrusions is preferable. It is preferable that the implantation part width with respect to the width | variety of the said wing | blade part tip is 2.1 to 2.5 times. An erosion prevention shield part is provided on the leading side of the wing tip, the implantation part is a fork type, and a plurality of pin insertion holes for fixing to the rotor shaft are provided, and the diameter of the insertion hole is on the wing part side. It is preferably larger than the opposite side.
[0044]
(9) The low pressure steam turbine rotor shaft is C0.2 to 0.3%, Si0.15% or less, Mn 0.25% or less, Ni 3.25 to 4.5%, Cr 1.6 to 2.5% by weight. , Mo 0.25 to 0.6%, V 0.05 to 0.25%, Fe 92.5% or more of a low alloy steel having a total tempered bainitic structure is preferable, similar to the high pressure and medium pressure rotor shaft described above It is preferable to manufacture by the manufacturing method. In particular, the amount of Si is 0.05% or less and Mn is 0.1% or less, and other raw materials having as low impurities as P, S, As, Sb and Sn are used, and the total amount is 0.025% or less, preferably 0.015. It is preferable to make a super-clean production using a raw material with few impurities used so as to be less than or equal to%. P and S are each preferably 0.010% or less, Sn, As 0.005% or less, and Sb 0.001% or less. This rotor shaft has a 0.02% proof stress of 80kg / mm at room temperature in the center.² Above, 0.2% proof stress is 87.5kg / mm² Above or tensile strength is 92kg / mm² Above, FATT is -5 ° C or lower or 20 ° C V notch impact value is 10kg · m / cm²The banite steel which is the above is preferable. The rotor shaft according to the present invention is preferably provided with a fork type rotor blade having a center hole and a reverse Christmas tree type without a center hole.
[0045]
(10) Other than the last stage of the blade for low-pressure turbine and the nozzles are C0.05 to 0.2%, Si 0.1 to 0.5%, Mn 0.2 to 1.0%, Cr 10 to 13%, Mo 0.04 Fully tempered martensitic steel with ˜0.2% is preferred.
[0046]
(11) Carbon cast steel having C0.2 to 0.3%, Si 0.3 to 0.7%, and Mn 1% or less is preferable for the low pressure turbine inner and outer casings.
[0047]
(12) The main steam stop valve casing and steam control valve casing are C0.1 to 0.2%, Si 0.1 to 0.4%, Mn 0.2 to 1.0%, Cr 8.5 to 10.5%, Mo 0.3 to 1.0%, W 1.0 to 3.0%, V 0.1 to 0.3%, Nb 0.03 to 0.1%, N 0.03 to 0.08%, B 0.0005 to 0 All tempered martensitic forged steel containing 0.003% is preferred.
[0048]
(13) C10 to 0.20%, Si 0.05 to 0.6%, Mn 0.1 to 1.0%, Ni 0.1 to 0 for high pressure turbine, medium pressure turbine and high and medium pressure turbine outer casing. 0.5%, Cr 1 to 2.5%, Mo 0.5 to 1.5%, V 0.1 to 0.35%, preferably Al 0.025% or less, B 0.0005 to 0.004% and Ti 0.005%. It is preferable to produce the cast steel having at least one of 0.5 to 0.2% and having a total tempered bainite structure. In particular, C 0.10 to 0.18%, Si 0.20 to 0.60%, Mn 0.20 to 0.50%, Ni 0.1 to 0.5%, Cr 1.0 to 1.5%, Mo 0.9 to 1 Cast steels containing 0.2%, V 0.2 to 0.3%, Al 0.001 to 0.005%, Ti 0.045 to 0.10% and B 0.0005 to 0.000020% are preferred. More preferably, the Ti / Al ratio is 0.5-10.
[0049]
(14) First stage blades of high-pressure, medium-pressure and high-medium-pressure turbines (high-pressure side and medium-pressure side) at a steam temperature of 610 to 650 ° C. The intermediate pressure side of the turbine and the high-medium pressure turbine is replaced with the above-described martensite steel up to two stages by weight, C 0.03 to 0.20% (preferably 0.03 to 0.15%), Cr 12 to 20%, Mo 9-20% (preferably 12-20%), Co 12% or less (preferably 5-12%), Al 0.5-1.5%, Ti 1-3%, Fe 5% or less, Si 0.3% or less, Mn0 In addition to 0.2% or less, B0.003 to 0.015%, Ni-based alloys containing one or more of Mg 0.1% or less, rare earth elements 0.5% or less, and Zr 0.5% or less can be used. The following content of each element includes 0%. The Ni-based alloy is subjected to solution treatment and aging treatment after melt forging.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
A 50 kg steel ingot was melted using a high frequency melting furnace and hot forged. In order to prevent a forging crack, it carried out at the temperature of 1150 degrees C or less. In addition, after annealing heat treatment of this forged steel, it was heated to 1050 ° C. and subjected to quenching treatment simulating the rotor shaft (water spray cooling is performed in the actual rotor shaft), and then tempered at 680 to 740 ° C., A creep rupture test piece was prepared. Table 1 shows the chemical composition (% by weight) of the steel ingot. No. No. 1 is a comparative material, no. 2 and 3 are materials of the present invention.
[0051]
[Table 1]

[0052]
Table 2 shows the creep rupture strength of the test material at 650 ° C. As shown in the table, the Al content exceeding 0.006% particularly lowers the creep rupture strength in the specific composition of the present invention, and should be less than that. Furthermore, no. No. 1 in which Co was reduced to 2% or less and Ni was reduced to 0.2% or less. 2 and 3 have a creep rupture strength of 10.5 kg / mm for longer hours of 100,000 hours.²It can be seen that the creep rupture strength is better at longer time sides as 0.034 and 0.0067 with (Ni / Co) ratio of 0.09 or less.
[0053]
[Table 2]

[0054]
The rotor shaft in the present embodiment can be used for a high-pressure turbine, an intermediate-pressure turbine having a steam temperature inlet temperature of 600 ° C. or more to the first stage rotor blade, or a high-medium-pressure integrated steam turbine in which a high-pressure part and an intermediate-pressure part are integrated. These steam turbines become rotor shafts having a double-flow structure blade implantation structure that flows toward the opposite outer sides. Further, the cladding portion of any of the rotor shafts is provided with a cladding of Cr—Mo low alloy steel having a bainite structure or a sleeve thereof. In particular, the present embodiment is suitable for an ultra super critical pressure power plant having a single-machine output of 1000 MW or more using steam temperatures of a high-pressure turbine 600 ° C., an intermediate-pressure turbine 620 ° C., or a high-pressure turbine and an intermediate-pressure turbine 620 ° C. Furthermore, these steam temperatures can be applied to 630-650 ° C.
[0055]
[Example 2]
Table 3 shows the main specifications of the steam temperature of 625 ° C. and 1050 MW steam turbine according to the present invention. In this embodiment, the blade length of the last stage rotor blade in a cross-compound type four-flow exhaust, low-pressure turbine is 43 inches, turbine configuration A is 3000 r / min with two HP-IP and LP, and turbine configuration B is HP- The rotor shafts having the same rotational speed of 3000 r / min for LP and IP-LP and exposed to high temperatures of HP and IP are shown in Table 4 based on the results obtained in Example 1. 12Cr steel is used. Steam temperature of high pressure part (HP) is 625 ° C, 250kgf / cm²The steam temperature of the intermediate pressure part (IP) is heated to 625 ° C. by a reheater and is 45 to 65 kgf / cm.² It is operated at the pressure of The low pressure part (LP) enters at a steam temperature of 400 ° C. and is sent to the condenser with a vacuum of 100 ° C. or less and 722 mmHg.
[0056]
The total distance between the bearings of the high-pressure turbine and the intermediate-pressure turbine connected to the tandem and the distance between the bearings of the two low-pressure turbines connected to the tandem is about 31.5 m, which is compact.
[0057]
[Table 3]

[0058]
FIG. 1 is a cross-sectional configuration diagram of a structure in which the high-pressure and intermediate-pressure steam turbines in the turbine configuration A in Table 3 are coupled in tandem.
[0059]
(High pressure steam turbine)
In the figure, the high-pressure steam turbine on the left side is provided with a high-pressure axle 23 in which high-pressure blades 16 are implanted in a high-pressure internal casing 18 and a high-pressure external casing 19 on the outside thereof. The high-temperature and high-pressure steam passes through the main steam pipe, passes through the main steam inlet 28 from the flange and elbow 25 constituting the main steam inlet, and is guided from the nozzle box 38 to the first stage double-flow rotor blade. The first stage is a double flow, and eight stages are provided on one side. A stationary blade is provided for each of these blades. The moving blade is a vertical dovetail type, double tinon, and the first blade length is about 35 mm. The length between the axles is about 5.3 m, the diameter of the smallest part corresponding to the stationary blade part is about 710 mm, and the ratio of the length to the diameter is about 8.2.
[0060]
The materials shown in Table 4 to be described later are used for the first stage blade and the first stage nozzle, and the other blades and nozzles are all made of 12% Cr steel containing no W, Co, or B. The length of the blade portion of the moving blade is 35 to 50 mm in the first stage, and becomes longer in each stage from the second stage to the last stage. In particular, the length from the second stage to the last stage is 65 to 65 depending on the output of the steam turbine. 180 mm, the number of stages is 9 to 12, and the length of the wings of each stage is a length adjacent to the upstream side on the downstream side at a rate of 1.10 to 1.15, and downstream. The ratio gradually increases on the side.
[0061]
(Medium pressure steam turbine)
In the figure, the intermediate pressure steam turbine on the right rotates the generator together with the high pressure steam turbine with the steam discharged from the high pressure steam turbine again heated to 625 ° C. by the reheater, and rotates at 3000 rpm. Rotated by number. Similar to the high-pressure turbine, the intermediate-pressure turbine has an intermediate-pressure internal second casing 21 and an intermediate-pressure external casing 22, and a stationary blade is provided in opposition to the intermediate-pressure moving blade 17. The rotor blades 17 are double-streamed in six stages, and are provided in a substantially symmetrical structure with respect to the longitudinal direction of the intermediate pressure axle. The first stage blade length is about 100 mm and the last stage blade length is about 230 mm. The first and second level dovetails are of the inverted Christmas tree type. The diameter of the rotor shaft at the portion corresponding to the stationary blade before the final stage moving blade is about 630 mm, which is about 9.2 times the bearing distance of 5.8 m.
[0062]
In this embodiment, 12% Cr steel not containing W, Co and B is used except that the materials shown in Table 4 described later are used for the first stage blade and the first stage nozzle. The length of the blade portion of the moving blade in this embodiment becomes longer in each stage from the first stage to the last stage, and the length from the first stage to the last stage is 60 to 300 mm depending on the output of the steam turbine. In the stage, the length of the wing portion of each stage is a length adjacent to the upstream side on the downstream side, and is increased at a rate of 1.1 to 1.2.
[0063]
The rotor shaft has a larger diameter than the portion where the rotor blade is implanted corresponding to the stationary blade, and its axial width increases as the blade length of the rotor blade increases. The ratio of the width to the blade length of the moving blade is 0.35 to 0.8 from the first stage to the last stage, and is gradually reduced from the first stage to the last stage.
[0064]
The first stage turbine blades of the high pressure turbine have a saddle type implant, and the turbine blades of the second and subsequent stages of the high pressure turbine and all the stages of the intermediate pressure turbine are of the inverted Christmas tree type.
[0065]
(Low pressure steam turbine)
FIG. 2 is a sectional view of the low-pressure turbine. The low-pressure turbine is coupled to two tandems and has almost the same structure. Each of the moving blades 41 has eight stages on the left and right sides and is substantially symmetric with respect to the left and right. The nozzle box 45 is a double flow type.
[0066]
The rotor shaft 44 includes, by weight, C 0.2 to 0.3%, Si 0.03 to 0.1%, Mn 0.1 to 0.2%, P 0.01% or less, S 0.01% or less, Ni 3.5 to 4.5%, Cr 1 .8-2.5%, Mo0.3-0.5%, V0.1-0.2%, Al0.01% or less, Sn0.005% or less, As0.005% or less, Sb0.001% or less Tempered bainitic steel is used. These steels have a total tempered bainitic structure after hot forging, after heating at 840 ° C. × 3 h, after quenching at 100 ° C./h, and after tempering at 575 ° C. × 32 h. 0.02% yield strength 80kg / mm²Above, 0.2% proof stress 87.5kg / mm²Above, tensile strength 100kg / mm² As described above, the V notch impact value is 10 kg-m or more, FATT is -20 ° C. or less, and has high strength and high toughness, and can be implanted with a blade length of 43 to 50 inches as the final stage moving blade of this embodiment. there were.
[0067]
In the 43 inch blade of this example, C0.14%, Si0.04%, Mn0.15%, Cr11.5%, Ni2.60%, Mo2.30%, V0.27%, Nb0.10%, Quenching and tempering were performed using martensitic steel containing N 0.07%. This product has a tensile strength of 134 kg / mm²V notch impact value is 5.0kg-m / cm²Met.
[0068]
For the moving blades and stationary blades other than the final stage, 12% Cr steel containing 0.1% Mo is used. The inner and outer casing material is C0.25% cast steel. The distance between the centers of the bearings 43 in this embodiment is 7500 mm, the diameter of the rotor shaft corresponding to the stationary blade portion is about 1280 mm, and the diameter at the moving blade implantation portion is 2275 mm.
[0069]
To the erosion shield for preventing erosion due to water droplets in the steam, a Co-based alloy stellite plate containing C1.0%, Cr28.0% and W4.0% by weight was joined by electron beam welding. In the present embodiment, the continuous cover is formed by cutting after forging as a whole. The continuous cover can also be formed mechanically and integrally.
[0070]
In the low-pressure turbine of the present embodiment, the axial width of the moving blade implantation portion is gradually increased in four stages from the first stage to the third stage, the fourth stage, the fifth stage, the sixth stage to the seventh stage, and the eighth stage. Is about 2.5 times larger than the width of the first stage.
[0071]
In addition, the diameter of the part corresponding to the stationary blade part is small, and the axial width of that part is gradually increased from the first stage moving blade side to the fifth, sixth and seventh stages. The width on the final stage side is about 1.9 times larger than that between the first stage and the second stage.
[0072]
The diameter of the implanted portion of the moving blade is larger than that of the portion corresponding to the stationary blade, and the width of the implanted portion increases as the blade length of the moving blade increases. The ratio of the width to the blade length of the moving blade is 0.15 to 0.19 from the first stage to the last stage, and is gradually reduced from the first stage to the last stage.
[0073]
Further, the width of the rotor shaft at the portion corresponding to each stationary blade is gradually increased in each stage from between the first stage and the second stage to between the last stage and the front thereof. The ratio of the width to the blade length of the moving blade is 0.25 to 1.25, and decreases from the upstream side to the downstream side.
[0074]
Two low-pressure turbines are connected to the tandem, and the total distance between the bearings is about 18.3 m. The distance between the bearings of the two low-pressure turbines connected to the tandem with respect to the blade length of the last stage blade of the low-pressure turbine. The total ratio is 16.7.
[0075]
This embodiment has the same configuration for a 1000 MW class large-capacity power plant having a steam inlet temperature of 610 ° C. for the high-pressure steam turbine and the medium-pressure steam turbine and a steam inlet temperature of 385 ° C. for the two low-pressure steam turbines. can do.
[0076]
(Power plant)
The power plant in this embodiment is mainly a coal-fired boiler, high pressure turbine, medium pressure turbine, two low pressure turbines, condenser, condensate pump, low pressure feed water heater system, deaerator, boost pump, feed water pump, high pressure feed water It consists of a heater system. The super high temperature and high pressure steam generated in the boiler enters the high pressure turbine to generate power, and then reheats again in the boiler to enter the intermediate pressure turbine to generate power. The intermediate-pressure turbine exhaust steam enters the low-pressure turbine, generates power, and then condenses in the condenser. This condensate is sent to the low-pressure feed water heater system and deaerator by the condensate pump. The feed water deaerated by the deaerator is sent to a high-pressure feed water heater by a booster pump and a feed water pump, and after being heated, returns to the boiler.
[0077]
Here, in the boiler, the feed water passes through a economizer, an evaporator, and a superheater and becomes high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that has heated the steam exits the economizer and enters the air heater to heat the air. Here, a feed water pump driving turbine that is operated by extracted steam from an intermediate pressure turbine is used to drive the feed water pump.
[0078]
In a high-temperature and high-pressure steam turbine plant configured in this way, the temperature of the feed water leaving the high-pressure feed water heater system is much higher than the feed water temperature in the conventional thermal power plant, so inevitably the node in the boiler The temperature of the combustion gas leaving the charcoal is also much higher than that of a conventional boiler. For this reason, heat recovery from this boiler exhaust gas is carried out so as not to lower the gas temperature.
[0079]
As a rotor shaft for a 1050 MW class generator, a rotor shaft having higher strength is used. In particular, C 0.15 to 0.30%, Si 0.1 to 0.3%, Mn 0.5% or less, Ni 3.25 to 4.5%, Cr 2.05 to 3.0%, Mo 0.25 to 0.3. It has a total tempered bainitic structure containing 60%, V 0.05 to 0.20%, and a room temperature tensile strength of 93 kgf / mm.²Above, especially 100kgf / mm²As described above, 50% FATT is preferably 0 ° C. or less, particularly −20 ° C. or less, the magnetizing force at 21.2 KG is 985 AT / cm or less, and the total amount of P, S, Sn, Sb, As as impurities Is preferably 0.025% or less and the Ni / Cr ratio is 2.0 or less.
[0080]
A center hole is provided in any of the rotor shafts of the high pressure, intermediate pressure, and low pressure turbines, and the presence or absence of defects is inspected through ultrasonic inspection, visual inspection, and fluorescence inspection through the center hole. Moreover, it can carry out by ultrasonic inspection from the outer surface, and there may be no central hole.
[0081]
Table 4 shows the chemical composition (% by weight) of materials used for the main parts of the high-pressure turbine, intermediate-pressure turbine, and low-pressure turbine according to the power plant of this example. In this example, the high-temperature part and the high-temperature part of the medium-pressure part all have a thermal expansion coefficient of about 12 × 10 having a ferrite crystal structure.^-6Since there was no difference in thermal expansion coefficient, there was no problem at all.
[0082]
[Table 4]

[0083]
The rotor shaft of the high-pressure turbine and the medium-pressure turbine was prepared by melting 30 tons of heat-resistant steel listed in Table 4 in an electric furnace, deoxidizing it with carbon, casting it into a mold, and forging it to produce an electrode rod. As an electrode rod, electroslag was remelted so as to melt from the upper part to the lower part of the cast steel, and forged into a rotor shape (diameter 1050 mm, length 3700 mm). This forging was performed at a temperature of 1150 ° C. or lower in order to prevent forging cracks. In addition, this forged steel is annealed and heated to 1050 ° C., water spray cooling quenching treatment, tempering twice at 570 ° C. and 690 ° C., and the final shape is obtained by cutting. In the high-pressure turbine, the upper side of the electroslag steel ingot is the first stage blade side and the lower part is the last stage side. Each rotor shaft has a central hole, and the central hole can be eliminated by reducing impurities. And Al is 0.004% and Ni / Co ratio is 0.04. 10 at 650 ° C. at the center of the rotor shaft of this example.^Threeh, 10^Fourh and 10^FiveThe creep rupture strength of h is No. 1 in Table 1. It was equivalent to 2,3. In particular, it showed high strength on the long time side.
[0084]
Further, as a result of investigating the center portion of the rotor shaft, characteristics (625 ° C, 10^Fiveh Strength ≧ 10kgf / mm², 20 ° C. impact absorption energy ≧ 1.5 kgf−m) was sufficiently satisfied. This demonstrated that a steam turbine rotor that can be used in steam at 620 ° C. or higher can be manufactured.
[0085]
The high pressure and intermediate pressure blades and nozzles are also melted in the vacuum arc melting furnace and heat-treated steel listed in Table 4 and forged into blade and nozzle material shapes (width 150 mm, height 50 mm, length 1000 mm). And molded. This forging was performed at a temperature of 1150 ° C. or lower in order to prevent forging cracks. The forged steel is heated to 1050 ° C., subjected to oil quenching, tempered at 690 ° C., and then cut into a predetermined shape.
[0086]
Further, as a result of investigating the characteristics of this blade, the characteristics required for the first stage blade of a high-pressure / medium-pressure turbine (625 ° C., 10^Fiveh Strength ≧ 15kgf / mm²) Was sufficiently satisfied. This demonstrated that a steam turbine blade that can be used in steam at 620 ° C. or higher can be produced.
[0087]
The inner casing, the main steam stop valve casing, and the steam control valve casing of the high-pressure part and the intermediate-pressure part were prepared by melting the heat-resistant cast steel shown in Table 4 in an electric furnace, refining the ladle, and casting it into a sand mold. By carrying out sufficient refining and deoxidation before casting, a product having no casting defects such as shrinkage cavities was obtained. The weldability evaluation using this casing material was performed according to JIS Z3158. Preheating, between passes, and after heat start temperature were 200 ° C., and post heat treatment was 400 ° C. × 30 minutes. The material of the present invention had no weld cracks and good weldability.
[0088]
Furthermore, as a result of investigating the characteristics of this casing, the characteristics required for high-pressure, medium-pressure, and high-medium pressure turbine casings (625 ° C., 10^Fiveh Strength ≧ 10kgf / mm², 20 ° C. impact absorption energy ≧ 1 kgf−m) was sufficiently satisfied and welding was confirmed. This demonstrated that a steam turbine casing that can be used in steam at 620 ° C. or higher can be produced.
[0089]
In this example, Cr—Mo low alloy steel was overlay welded to the journal portion of the high and medium pressure turbine rotor shaft to improve the bearing characteristics. Welded 8 layers by combining the welding rods used for each layer shown in Table 6 using the (wt%) coated arc welding rod (4.0 mm in diameter) shown in Table 5 as the test welding rod. It was. The thickness of each layer was 3-4 mm, the total thickness was about 28 mm, and the surface was ground about 5 mm. The welding conditions are preheating, between passes, stress relief annealing (SR) start temperature is 250 to 350 ° C., and SR treatment condition is 630 ° C. × 36 hours.
[0090]
[Table 5]

[0091]
[Table 6]

[0092]
In order to confirm the performance of the welded part, overlay welding was similarly performed on the plate material, and a 160 ° side bending test was performed. However, no crack was observed in the welded part. There was no adverse effect on the material, and it was excellent in oxidation resistance.
[0093]
Example 3
Table 7 shows the main specifications of a steam turbine power plant with a steam temperature of 600 ° C. and a rated output of 700 MW. This example is a tandem compound double flow type, the last stage blade length in a low pressure turbine is 46 inches, HP (high pressure) / IP (medium pressure) integrated type and LP 1 unit (C) or 2 units (D) 3000 rpm The high pressure part and the low pressure part are composed of the main materials shown in Table 4 above. Steam temperature of high pressure part (HP) is 600 ° C, 250kgf / cm² The steam temperature of the intermediate pressure part (IP) is heated to 600 ° C. by a reheater and is 45 to 65 kgf / cm.² It is operated at the pressure of The low pressure part (LP) enters at a steam temperature of 400 ° C., and is sent to the condenser with a vacuum of 100 ° C. or less and 722 mmHg.
[0094]
The steam turbine power plant (D) provided with a high-medium pressure integrated turbine and two low-pressure turbines in tandem in this embodiment has a distance between the bearings of about 22.7 m, and the blade length of the last stage blade of the low-pressure turbine. The total distance of the distance between the bearings per 1 MW of the rated output 700 MW of the power plant is 32.4 mm. Further, in the steam turbine power plant (C) including the high-medium pressure integrated turbine and one low-pressure turbine in the present embodiment, the distance between the bearings is about 14.7 m, and the blade length of the final stage moving blade of the low-pressure turbine. It is 12.6 times (1168 mm), and 21.0 mm per rated output of 1 MW.
[0095]
[Table 7]

[0096]
FIG. 3 is a cross-sectional configuration diagram of a high-pressure / medium-pressure integrated steam turbine. The high pressure side steam turbine is provided with a high / medium pressure axle (high / medium pressure integrated rotor shaft) 33 in which high pressure blades 16 are implanted in a high pressure internal casing 18 and a high pressure external casing 19 on the outside thereof. The high-temperature and high-pressure steam is obtained by the above-described boiler, passes through the main steam pipe, passes through the main steam inlet 28 from the flange and elbow 25 constituting the main steam inlet, and is led from the nozzle box 38 to the first stage blade. Steam enters from the center side of the rotor shaft and flows to the bearing side. The rotor blades are provided in 8 stages on the high pressure side on the left side in the figure and 6 stages on the intermediate pressure side (about half of the right side in the figure). A stationary blade is provided for each of these blades. The rotor blades are saddle type or getter type, dovetail type, double tinon, high pressure side first stage blade length of about 40 mm, and medium pressure side first stage blade length is 100 mm. The length between the bearings 43 is about 6.7 m, and the diameter of the smallest portion corresponding to the stationary blade portion is about 740 mm, and the ratio of the length to the diameter is about 9.0.
[0097]
A material having the chemical composition (% by weight) shown in Table 4 was used for the main part of the high and medium pressure turbine and the low pressure turbine of this example. The one described in Example 2 was used as the high and medium pressure integrated rotor shaft. In addition, the high and medium pressure integrated rotor shaft has a center hole, and in particular, P is 0.010% or less, S is 0.005% or less, As is 0.005% or less, Sn is 0.005% or less, and Sb is 0.003% or less. The central hole can be eliminated by the high purity. Furthermore, a build-up weld layer of Cr—Mo low alloy steel on the bearing portion was formed in the same manner. Further, as the generator shaft, one having a higher strength is used as in the second embodiment.
[0098]
The rotor shaft on the high pressure side has the largest width at the root of the first stage and the last stage where the rotor blades are implanted. The second to seventh stages are smaller, and the first stage is 0.40 to 0.56 times the same. The final stage is between the first stage and the second to seventh stages, and is 0.46 to 0.62 times as large as the first stage.
[0099]
The blade length of the moving blade on the high-pressure side is 35-50 mm in the first stage and becomes longer in each stage from the second stage to the last stage, and in particular, the length from the second stage to the last stage depending on the output of the steam turbine. Is in the range of 50 to 150 mm, the number of stages is in the range of 7 to 12 stages, and the length of the wings of each stage is 1.05 to 1.35 with the downstream side being adjacent to the upstream side. The ratio becomes longer in the double range, and the ratio gradually increases on the downstream side.
[0100]
The medium pressure steam turbine rotates the generator together with the high pressure steam turbine by the steam heated from the high pressure steam turbine by the reheater again at 600 ° C., and is rotated at a rotational speed of 3000 rpm. The medium pressure side turbine has a medium pressure internal second casing 21 and a medium pressure external casing 22 in the same manner as the high pressure side turbine, and a stationary blade is provided in opposition to the medium pressure moving blade 17. The medium pressure rotor blade 17 has six stages. The first stage blade length is about 130 mm, and the last stage blade length is about 260 mm. Dovetil is a reverse chestnut type.
[0101]
The rotor shaft on the medium pressure side has the largest axial width of the root of the rotor blade implantation at the first stage, the second stage is smaller than that, the third to fifth stages are smaller than the second stage, and the width of the final stage is the same. The size between the third and fifth stages and the second stage is 0.48 to 0.64 times that of the first stage. The first stage is 1.1 to 1.5 times the second stage.
[0102]
The length of the blade portion of the moving blade on the medium pressure side becomes longer in each stage from the first stage to the last stage, and the length from the first stage to the last stage is 90 to 350 mm and the number of stages is 6 to 9 depending on the output of the steam turbine. Within the range of the stage, the length of the wing part of each stage is longer at a rate of 1.10 to 1.25, with the downstream side being adjacent to the upstream side.
[0103]
The implanted portion of the moving blade has a larger diameter than the portion corresponding to the stationary blade, and its width is related to the length and position of the moving blade. The ratio of the width to the blade length of the moving blade is the largest at the first stage, 1.35 to 1.80 times, the second stage is 0.88 to 1.18 times, and the third to sixth stages become the final stage. It is small, 0.40 to 0.65 times.
[0104]
The high-medium pressure integrated turbine for a steam turbine power plant equipped with two low-pressure turbines coupled to the tandem of this embodiment has a bearing distance of about 6.7 m, and the blade length of the last stage blade of the low-pressure turbine ( 15.7 mm) and 5.7 mm per rated output of 1 MW.
[0105]
Also in the present embodiment, a built-up weld layer of low alloy steel is provided in the bearing portion of the high / medium pressure integrated steam turbine rotor shaft as in the second embodiment.
[0106]
FIG. 4 is a cross-sectional view of the low-pressure turbine. There are one low pressure turbine or two low pressure turbines, both of which are connected to the high and medium pressure turbine in tandem. The moving blade 41 has six stages on the left and right sides, is substantially symmetrical, and a stationary blade 42 is provided corresponding to the moving blade. The last stage blade has a length of 46 inches, and Ti-based alloy or high-strength 12% Cr steel is used as in the second embodiment. As in the second embodiment, the rotor shaft 44 is made of forged steel having a super-tempered tempered bainitic structure. 12% Cr steel containing 0.1% Mo is used for the moving blades and stationary blades other than the final stage and the preceding stage. For the inner and outer casing material, cast steel having the above-mentioned composition of C 0.25% is used. In this embodiment, the distance between the centers of the bearings 43 is 8 m, the diameter of the rotor shaft corresponding to the stationary blade portion is about 800 mm, and the diameter at the moving blade implantation portion is the same in each stage. The distance between the bearing centers with respect to the rotor shaft diameter corresponding to the stationary blade portion is 10 times.
[0107]
In the 46 inch blade of this example, C0.23%, Si0.06%, Mn0.15%, Cr11.4%, Ni2.65%, Mo3.10%, V0.25%, Nb0.11%, Quenching and tempering were performed using martensitic steel containing N 0.06%. This product has a tensile strength of 145 kg / mm²V notch impact value is 6.2kg-m / cm²Met.
[0108]
The rotor shaft is provided with a moving blade implantation portion, and the reverse Christmas tree type is used in the same manner as the fork type in the final dovetail.
[0109]
In the low-pressure turbine, the axial width of the root portion of the rotor blade implantation is the smallest at the first stage, the second and third stages are the same on the downstream side, the fourth and fifth stages are the same, and gradually increase in four stages. The width is 6.2 to 7.0 times larger than the width of the first stage. The second and third stages are 1.15 to 1.40 times the first stage, the fourth and fifth stages are 2.2 to 2.6 times the second and third stages, and the last stage is 2.8 to 3.2, which is the fourth and fifth stages. It has doubled. The width of the root portion is indicated by a point connecting a diverging extension line and the diameter of the rotor shaft.
[0110]
The blade length of the moving blade in this embodiment becomes longer at each stage as it reaches the final stage from 4 ″ to 46 ″ at the first stage, and the maximum is 8 stages. The blade length of each stage is the upstream side at the downstream side. On the other hand, the adjacent length is gradually increased within a range of 1.2 to 1.9 times.
[0111]
The root portion of the moving blade has a larger diameter than the portion corresponding to the stationary blade, and its width increases as the blade length of the moving blade increases. The ratio of the width to the blade length of the moving blade is 0.30 to 1.5 from the first stage to the last stage, and the ratio gradually decreases from the first stage to the last stage. The ratio of the latter stage is gradually smaller within the range of 0.15 to 0.40 than that of the immediately preceding stage. The final stage is a ratio of 0.50 to 0.65.
[0112]
In this embodiment, the average diameter of the final stage blades was 3000 rpm, 43 ″ blades 2590 mm, 3600 rpm, 36 ″ blades 2160 mm, 3000 rpm, 46 ″ blades 2665 mm, 3600 rpm, 38 ″ blades 2220 mm.
[0113]
In the erosion shield in this embodiment, a stellite alloy plate is joined by electron beam welding or TIG welding in the same manner as described above. The erosion shield is welded over the entire length of the erosion shield member at two locations on the front side and the back side where the wet steam directly hits. The front side is wider than the back side, and the upper and lower ends are also welded.
[0114]
The high-temperature high-pressure steam turbine power plant in this embodiment is mainly a boiler, a high-medium pressure turbine, a low-pressure turbine, a condenser, a condensate pump, a low-pressure feed water heater system, a deaerator, a boost pump, a feed pump, and a high-pressure feed water heater system. Etc. That is, the super high temperature and high pressure steam generated in the boiler enters the high pressure turbine and generates power, and then is reheated again in the boiler to enter the intermediate pressure turbine and generate power. The high and medium pressure turbine exhaust steam enters the low pressure turbine to generate power, and then condenses in the condenser. This condensate is sent to a low-pressure feed water heater system and a deaerator by a condensate pump. The feed water deaerated by the deaerator is sent to a high-pressure feed water heater by a booster pump and a feed water pump, and after being heated, returns to the boiler.
[0115]
Here, in the boiler, the feed water passes through a economizer, an evaporator, and a superheater and becomes high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that has heated the steam exits the economizer and enters the air heater to heat the air. Here, a feed water pump driving turbine that is operated by extracted steam from an intermediate pressure turbine is used to drive the feed water pump.
[0116]
In a high-temperature and high-pressure steam turbine plant configured in this way, the temperature of the feed water leaving the high-pressure feed water heater system is much higher than the feed water temperature in the conventional thermal power plant, so inevitably the node in the boiler The temperature of the combustion gas leaving the charcoal is also much higher than that of a conventional boiler. For this reason, heat recovery from this boiler exhaust gas is carried out so as not to lower the gas temperature.
[0117]
In addition to this embodiment, the same applies to a 1000 MW class large-capacity power plant in which the steam inlet temperature of the high and medium pressure steam turbine is 610 ° C or higher, the steam inlet temperature to the low pressure steam turbine is about 400 ° C, and the outlet temperature is about 60 ° C. It can be configured. Even when the vapor temperature is 593 ° C. or 630 ° C., the material configuration and structure of this embodiment can be used as they are.
[0118]
【The invention's effect】
According to the present invention, it is possible to obtain a steam turbine rotor shaft excellent in high-temperature and long-side strength at a specific temperature of 600 ° C. or more and 50,000 hours or more and a long-time side. By using the turbine, particularly when applied to an ultra-supercritical steam turbine, the steam temperature of the steam turbine can be increased to 650 ° C. or more, and a remarkable effect is obtained in improving the thermal efficiency of the steam turbine power plant.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in which a high-pressure steam turbine and an intermediate-pressure steam turbine are connected.
FIG. 2 is a cross-sectional view of a low pressure steam turbine.
FIG. 3 is a cross-sectional view of a high intermediate pressure steam turbine.
FIG. 4 is a cross-sectional view of a low pressure steam turbine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st bearing, 2 ... 2nd bearing, 3 ... 3rd bearing, 4 ... 4th bearing, 5 ... Thrust bearing, 10 ... 1st shaft packing, 11 ... 2nd shaft packing, 12 ... 3rd shaft packing, DESCRIPTION OF SYMBOLS 13 ... 4th shaft packing, 14 ... High pressure partition plate, 15 ... Medium pressure partition plate, 16 ... High pressure moving blade, 17 ... Medium pressure moving blade, 18 ... High pressure internal casing, 19 ... High pressure external casing, 20 ... Medium Pressure inner first casing, 21 ... Medium pressure inner second casing, 22 ... Medium pressure outer casing, 23 ... High pressure axle, 24 ... Medium pressure axle, 25 ... Flange, elbow, 26 ... Front bearing box, 28 ... Main steam inlet, 29 ... reheat steam inlet, 30 ... high pressure steam exhaust port, 31 ... cylinder connecting pipe, 33 ... high / medium pressure axle, 38 ... nozzle box (high pressure first stage), 39 ... thrust bearing wear blocking device, 40 ... warm-up steam inlet, 41 ... moving blade, 42 ... stationary blade, 43 ... bearing, 44 ... rotor shaft.

Claims (1)

By weight, C 0.05 to 0.20%, Si 0.2% or less, Mn 0.01 to 1.5%, Ni 0.01 to 0.3%, Cr 9.0 to 13.0%, Mo 0.05 to 0 0.5%, W 0.5 to 5.0%, V 0.05 to 0.30%, Nb 0.01 to 0.20%, Co 1.0 to 2.0%, N 0.01 to 0.1%, B0 Including 0.001 to 0.030% and Al 0.0005 to 0.006%, and the (Ni / Co) ratio is 0.00. Is 1 hereinafter, consists martensitic steel consisting of the balance Fe and unavoidable impurities, after cooling rate at the center holes were hardened so that 50 to 600 ° C. / h, steam, characterized by tempering Manufacturing method for turbine rotor shaft.

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