JP4052405B2 - Control valve control system when steam turbine cooling steam is introduced - Google Patents

Control valve control system when steam turbine cooling steam is introduced Download PDF

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JP4052405B2
JP4052405B2 JP13976998A JP13976998A JP4052405B2 JP 4052405 B2 JP4052405 B2 JP 4052405B2 JP 13976998 A JP13976998 A JP 13976998A JP 13976998 A JP13976998 A JP 13976998A JP 4052405 B2 JP4052405 B2 JP 4052405B2
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steam
vacuum
control valve
turbine
steam turbine
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JPH11336509A (en
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昌和 井上
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Mitsubishi Heavy Industries Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
    • F01K23/101—Regulating means specially adapted therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、ガスタービンと蒸気タービンを一軸に連結したコンバインドプラントにおける蒸気タービン冷却蒸気導入時の加減弁制御システムに関し、起動時の冷却蒸気使用量を少くするように制御し、補助蒸気の使用量も少し、補助蒸気なしでも起動が可能となるように制御するものである。
【０００２】
【従来の技術】
一軸コンバインドプラントにおいては、ガスタービンと蒸気タービンが一軸で連結されており、起動の際には、起動用モータか、あるいは発電機をサイリスタで起動させて回転させ、ガスタービンを起動している。このために蒸気タービンでは起動時には風損により温度上昇が起こり、特に低圧タービン最終段において著しい温度上昇がある。そこで起動時には冷却蒸気を流してこの温度上昇を防止するようにしている。この冷却蒸気は起動時には、排熱回収ボイラで発生する蒸気が少いので充分な蒸気量が得られず、外部から補助蒸気を導入している。
【０００３】
図７は一軸コンバインド発電プラントの起動時の制御系統図であり、１１はガスタービン、１２は蒸気タービン、１３は発電機であり、これら１１〜１３は一軸に連結されて回転する。１４は復水器であり蒸気タービン１２の排気を海水で冷却して復水させるもので、内部は真空となっている。１５はポンプ、１６は排熱回収ボイラ、１７は煙突であり、排熱回収ボイラ１６はガスタービン１１の排気を導き、ポンプ１５で送られてきた復水を排熱により加熱して蒸気タービン１２に送る。
【０００４】
１８は開閉弁、１９は主開閉弁であり、２０は蒸気流量を制御する加減弁である。２１は圧力検出器であり、蒸気タービン入口の低圧蒸気圧力Ｐ1 を検出する。３０は制御装置、４０は補助蒸気発生装置であり、４１はその蒸気の開閉弁である。
【０００５】
図５は制御装置３０での制御ブロック図であり、制御装置３０には関数発生器３１において低圧蒸気タービン入口蒸気圧力と加減弁開度との最適な関係が設定されており、関数発生器３１は入力する圧力検出器２１の検出器Ｐ1 に対応する最適な加減弁の開度信号Ｓ1 を発生し、加減弁２０を制御する。
【０００６】
図６は上記に説明の蒸気圧力と加減弁の開度との関係を示す一般的な図で、蒸気タービンの冷却蒸気は、運転継続できる最低真空度において必要な蒸気流量を得られるように計画しているため、入口圧力が低下すると加減弁開度が大きくなる設定にされている。図５に示す関数発生器３１は入力する圧力値Ｐ1 に応じてこのような加減弁の開度信号Ｓ1 を出力する。
上記構成の一軸コンバインド発電プラントにおいては、ガスタービン１１の運転中には、その排気は排熱回収ボイラ１６に導かれ、ここで排熱が回収されて煙突１７より大気に放出される。排熱により加熱された蒸気は開閉弁１８、主開閉弁１９、加減弁２０を通り蒸気タービン１２に戻され、仕事をして発電機１３を回し、発電に供される。蒸気タービン１２の排気は復水器１２で復水し、再び排熱回収ボイラ１６へ導かれる。
【０００７】
上記一軸コンバインドプラントの起動に際しては、起動用モータ２５又は発電機１３のインバータ制御によりガスタービン１１を駆動して起動するが、起動時には風損により蒸気タービン１２が温度上昇するので、これを防止するために開閉弁４１を開き、開閉弁１８を閉じて補助蒸気発生装置４０から補助蒸気を加減弁２０を介して蒸気タービン１２に供給する。この補助蒸気で立上がり時の所定時間ガスタービン１１を運転し、排熱回収ボイラ１６が充分立上がり、発生蒸気量が増加した段階で開閉弁４１を閉じ、開閉弁１８を開いて通常の運転に入るようにしている。この時の加減弁２０の開度制御は図５，図６で説明したように制御装置３０により行なわれる。
【０００８】
【発明が解決しようとする課題】
前述のように従来の一軸コンバインド発電プラントの起動に際しては、起動直後の排熱回収ボイラ１６の発生蒸気量が少いため補助蒸気発生装置４０から冷却蒸気を導入し、立上がり時の蒸気タービン１２の風損による温度上昇を防止している。この補助蒸気を使用しないで排熱回収ボイラ１６の発生蒸気のみを使用すると、必要蒸気量を得るために加減弁２０を開放するが排熱回収ボイラ１６の発生蒸気量に遅れがあり、そのためにボイラ内のドラム圧力が低下してしまい、ドラムのレベル制御ができなくなる。従って、起動時には補助蒸気発生装置４０の蒸気を使用する。
【０００９】
しかし、このような起動時のためには外部に大型の補助蒸気発生装置４０を必要とし、又、起動時の蒸気使用量も多く、補助蒸気の使用なしで排熱回収ボイラ１６で発生する蒸気のみで起動できるようにすることが以前より強く望まれていた。
【００１０】
そこで本発明では、起動時において、冷却蒸気温度が同じ場合に復水器の真空度が良くなると蒸気タービンのメタル温度も低下することが確認できたので、復水器の真空度の状態に応じて真空度が良ければ冷却蒸気流量を少くし、真空度が悪くなるとその程度に応じて冷却蒸気量を増すような制御を行うことにより、蒸気量のむだをなくし、補助蒸気の使用をなくすることのできる蒸気タービン冷却蒸気導入時の加減弁制御システムを提供することを課題としてなされたものである。
【００１１】
【課題を解決するための手段】
本発明は前述の課題を解決するために次の手段を提供する。
【００１２】
ガスタービンと一軸で連結する蒸気タービンと、同蒸気タービンの排気を復水する復水器と、前記蒸気タービンの入口蒸気圧力を検出する蒸気圧力検出器と、前記蒸気タービンへの蒸気流量を制御する加減弁と、前記蒸気圧力検出器の検出圧力値を入力し、同検出値に対応する前記加減弁の開度を求め、前記加減弁を制御する制御装置とを有する一軸コンバインドプラントの前記ガスタービン起動時に前記蒸気タービンに冷却蒸気を導入する時の加減弁制御システムにおいて；前記復水器には内部の真空度を検出する真空圧力検出器を設け、前記制御装置は同真空圧力検出器の検出値に応じて真空度が所定値よりも高真空状態の時には前記蒸気圧力検出器の検出値により求めた前記加減弁開度を絞り、逆に低真空状態の時には前記加減弁開度を拡大するように補正することを特徴とする蒸気タービン冷却蒸気導入時の加減弁制御システム。
【００１３】
一軸コンバインド発電プラントの起動時には、蒸気タービンは風損により温度上昇するため冷却蒸気を必要とするが、ガスタービン起動直後は排熱回収ボイラの発生蒸気量は少いため外部の補助蒸気源の補助蒸気を使用する。本発明はこの起動時の冷却蒸気を制御するものであり、復水器の真空圧力検出器の検出値が制御装置に入力される。復水器は蒸気タービンの排気を導き、海水で冷却して復水させるが、復水器内の真空度は海水の温度により変動する。海水の温度は夏場には高く、冬場には低くなっており、温度の低い冬場の方が復水器の真空度は高くなる。復水器の真空度が高くなると蒸気タービンのメタル温度も低くなるのでその分流入する冷却蒸気量も少くすることが可能である。本発明では真空圧力検出器からの検出値が高真空度の状態であると、制御装置は蒸気圧力検出器の検出値から求めた加減弁開度を絞るように、又、低真空度の状態であると加減弁開度を拡げるように補正し、加減弁を制御する。特に冬場のように復水器が高真空の状態にある時には冷却蒸気量を少くすることができ、補助蒸気を使用しなくても、わずかな排熱回収ボイラで冷却蒸気をまかなうことができる。
【００１４】
【発明の実施の形態】
以下、本発明の形態について図面に基づいて具体的に説明する。図１は本発明の実施の一形態に係る蒸気タービン冷却蒸気導入時の加減弁制御システムの全体の系統図である。図において符号１１乃至２１，２５，４０，４１は図７に示す従来の系統図と同じであるので詳しい説明は省略し、そのまま引用して説明するが、本発明の特徴部分は符号１の制御装置、２の真空圧力検出器の部分であり、以下に詳しく説明する。
【００１５】
図１において、１は制御装置であり、従来の制御装置３０と同じく圧力検出器２１からの検出信号を入力し、開閉弁１８，１９，４１及び加減弁２０を制御する点は同じであるが、本発明では復水器１４内の真空度を検出する真空圧力検出器２を設け、この検出信号を制御装置１に入力し、制御装置１では従来の蒸気タービン入口の蒸気圧力検出器Ｐ1 に基づいた加減弁２０の開度信号を補正するように制御する。
【００１６】
図２は上記に説明の制御装置１内の制御の内容を示し、（ａ）はそのブロック図、（ｂ）は開度信号を示す図である。図２（ａ）において、制御装置１は従来と同じく圧力検出器２１からの蒸気タービン入口蒸気圧力の信号Ｐ1 を入力し、関数発生器３１において圧力信号Ｐ1 の大小に応じてあらかじめ定められた開度信号Ｓ1 を出力する。
【００１７】
一方、真空圧力検出器２からは復水器１４内の真空圧力Ｐ2 が制御装置１に送られ、関数発生器３において真空度に応じて真空圧力が高ければ大きな補正値、真空度が低ければ小さな補正値を、開度補正信号Ｓ2 として出力する。これら両信号Ｓ1 , Ｓ2 は加算器４で加算され、加減弁２０の開度信号Ｓ3 が出力される。
図２（ｂ）はこの状態信号の状態を図示したもので、入口蒸気圧力Ｐ1 においてＳ1 の開度信号が出力され、真空度の高低に応じ、真空度が高ければ開度を減少し、低ければ開度を増大するように補正開度信号Ｓ2 により加算器４で補正された結果、Ｓ3 の開度信号となり、真空度を考慮した信号として加減弁２０の開度を制御する。
【００１８】
図３は低圧冷却蒸気流量（補助蒸気使用時で蒸気温度は１４０℃の場合）と低圧最終段静翼メタル温度との関係を示す図であり、圧力値は復水器内の真空度を示している。この図からも明らかなように、一軸コンバインド発電プラントの起動時においては、復水器の真空度が高い程低圧蒸気タービン最終段静翼のメタル温度が低くなることがわかる。
【００１９】
上記図３の結果を、蒸気量を一定として復水器内の真空度と低圧蒸気タービン最終段静翼のメタル温度との関係で一般的に図示すると図４のようになる。この結果から、起動時において復水器の真空度が高いと蒸気タービンのメタル温度が下がり、真空度が低いとメタル温度が高いことがわかり、蒸気タービンのメタル温度の上昇、下降は冷却蒸気流量に依存するので、この真空度に応じて冷却蒸気流量を最適に制御し、特に真空度が高い時には必要以上の蒸気を流さないようにすれば、起動時の冷却蒸気流量を少くすることができる。
【００２０】
復水器の真空度は復水器に導かれる海水の温度により変化し、海水の温度は夏場には高く、冬場には低い。従って復水器内の真空度は海水温度の低い冬場においては高くなる傾向にあり、この冬場では本発明の制御装置１により加減弁２０の開度信号Ｓ1 を補正信号Ｓ2 により補正することにより絞り方向の開度信号Ｓ3 として冷却蒸気流量を少くし、わずかな排熱回収ボイラ１６の発生蒸気量でも起動を可能とすることができる。従ってこのように真空度が良い状態では補助蒸気装置２１を使用しなくても良く、この場合には制御装置１は開閉弁４１を閉じるように制御する。
【００２１】
以上説明の実施の形態の蒸気タービン冷却蒸気導入時の加減弁制御システムによれば、一軸コンバインド発電プラントの起動時の冷却蒸気導入時の加減弁２０の制御において、制御装置１は蒸気タービンの入口低圧蒸気圧力Ｐ1 を検出し、関数発生器３１からこのＰ1 に対応する所定の弁開度信号Ｓ1 を出力し、更に、復水器１４の真空圧力検出器２からの真空圧力値Ｐ2 を入力し、関数発生器３よりこのＰ2 に対応する開度補正信号Ｓ2 を出力し、Ｓ1 をＳ2 で補正することにより加減弁開度信号Ｓ3 を出力するようにしたので、特に冬場のような復水器１４の真空度が高いと冷却蒸気量も少くなり、わずかな排熱回収ボイラ１６の発生蒸気量のみでも起動が可能となり、補助蒸気発生装置４０からの補助蒸気を不要とするものである。
【００２２】
【発明の効果】
本発明の蒸気タービン冷却蒸気導入時の加減弁制御システムは、ガスタービンと一軸で連結する蒸気タービンと、同蒸気タービンの排気を復水する復水器と、前記蒸気タービンの入口蒸気圧力を検出する蒸気圧力検出器と、前記蒸気タービンへの蒸気流量を制御する加減弁と、前記蒸気圧力検出器の検出圧力値を入力し、同検出値に対応する前記加減弁の開度を求め、前記加減弁を制御する制御装置とを有する一軸コンバインドプラントの前記ガスタービン起動時に前記蒸気タービンに冷却蒸気を導入する時の加減弁制御システムにおいて；前記復水器には内部の真空度を検出する真空圧力検出器を設け、前記制御装置は同真空圧力検出器の検出値に応じて真空度が所定値よりも高真空状態の時には前記蒸気圧力検出器の検出値により求めた前記加減弁開度を絞り、逆に低真空状態の時には前記加減弁開度を拡大するように補正することを特徴としている。このようなシステムにより、制御装置では復水器の真空度に応じて真空度が高い状態の時には加減弁の開度信号を補正し、加減弁を絞って冷却蒸気量を少くすることができるので、冷却蒸気量が少くて良く、わずかな排熱回収ボイラの発生蒸気でも起動が可能となり、補助蒸気を不要とするものである。
【図面の簡単な説明】
【図１】本発明の実施の一形態に係る蒸気タービン冷却蒸気導入時の加減弁制御システムの全体系統図である。
【図２】本発明の実施の一形態に係る加減弁制御システムの制御を示し、（ａ）はブロック図，（ｂ）は信号の説明図である。
【図３】一軸コンバインドプラントにおける起動時の冷却蒸気流量と蒸気タービンのメタル温度との関係を示す図である。
【図４】一軸コンバインドプラントにおける復水器の真空度と蒸気タービンのメタル温度との関係を示す図である。
【図５】従来の一軸コンバインドプラントの起動時の冷却蒸気流量を制御する制御のブロック図である。
【図６】従来の一軸コンバインドプラントにおける冷却蒸気圧力と加減弁開度との関係を示す図である。
【図７】従来の一軸コンバインドプラントにおける蒸気タービン冷却蒸気導入時の加減弁制御システムの全体系統図である。
【符号の説明】
１ 制御装置
２ 真空圧力検出器
３ 関数発生器
４ 加算器
１１ ガスタービン
１２ 蒸気タービン
１３ 発電機
１４ 復水器
１５ ポンプ
１６ 排熱回収ボイラ
１８，４１ 開閉弁
１９ 主開閉弁
２０ 加減弁
２１ 圧力検出器
４０ 補助蒸気発生装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control valve control system at the time of introduction of steam turbine cooling steam in a combined plant in which a gas turbine and a steam turbine are connected to one shaft, and controls the amount of cooling steam used at startup to reduce the amount of auxiliary steam used. However, it is controlled so that it can be started without auxiliary steam.
[0002]
[Prior art]
In a single-shaft combined plant, a gas turbine and a steam turbine are connected by a single shaft, and at the time of start-up, a start-up motor or a generator is started up by a thyristor and rotated to start up the gas turbine. For this reason, in a steam turbine, the temperature rises due to windage at the time of start-up, and particularly in the final stage of the low-pressure turbine, there is a significant temperature rise. Therefore, at the time of startup, cooling steam is flowed to prevent this temperature rise. At the time of start-up, since this cooling steam generates a small amount of steam in the exhaust heat recovery boiler, a sufficient amount of steam cannot be obtained, and auxiliary steam is introduced from the outside.
[0003]
FIG. 7 is a control system diagram at the time of starting up the single-shaft combined power plant, in which 11 is a gas turbine, 12 is a steam turbine, and 13 is a generator. These 11 to 13 are connected to a single shaft and rotate. A condenser 14 cools the exhaust of the steam turbine 12 with seawater and condenses it, and the inside is vacuum. Reference numeral 15 is a pump, 16 is an exhaust heat recovery boiler, and 17 is a chimney. The exhaust heat recovery boiler 16 guides the exhaust of the gas turbine 11, and heats the condensate sent by the pump 15 by exhaust heat to steam steam 12. Send to.
[0004]
18 is an on-off valve, 19 is a main on-off valve, and 20 is an adjusting valve for controlling the steam flow rate. 21 is a pressure detector, which detects a low-pressure steam pressure P 1 at the inlet of the steam turbine. 30 is a control device, 40 is an auxiliary steam generator, and 41 is an on-off valve for the steam.
[0005]
FIG. 5 is a control block diagram of the control device 30. In the control device 30, an optimum relationship between the low-pressure steam turbine inlet steam pressure and the control valve opening is set in the function generator 31. Generates an optimum valve opening / closing signal S 1 corresponding to the detector P 1 of the input pressure detector 21 and controls the valve 20.
[0006]
FIG. 6 is a general diagram showing the relationship between the steam pressure described above and the opening of the control valve, and the cooling steam of the steam turbine is planned so that the necessary steam flow rate can be obtained at the minimum vacuum level at which the operation can be continued. Therefore, the adjustment valve opening is set to increase as the inlet pressure decreases. The function generator 31 shown in FIG. 5 outputs such an opening / closing signal S 1 of the adjusting valve in accordance with the input pressure value P 1 .
In the single-shaft combined power plant configured as described above, during operation of the gas turbine 11, the exhaust gas is guided to the exhaust heat recovery boiler 16, where the exhaust heat is recovered and released from the chimney 17 to the atmosphere. The steam heated by the exhaust heat passes through the on-off valve 18, the main on-off valve 19, and the control valve 20, is returned to the steam turbine 12, works to rotate the generator 13, and is used for power generation. Exhaust gas from the steam turbine 12 is condensed by the condenser 12 and led to the exhaust heat recovery boiler 16 again.
[0007]
At the time of starting the single-shaft combined plant, the gas turbine 11 is driven by the starter motor 25 or the inverter 13 of the generator 13 to start. However, the temperature of the steam turbine 12 rises due to windage at the time of start-up. Therefore, the on-off valve 41 is opened, the on-off valve 18 is closed, and auxiliary steam is supplied from the auxiliary steam generator 40 to the steam turbine 12 through the control valve 20. The gas turbine 11 is operated for a predetermined time at the time of start-up with the auxiliary steam, the exhaust heat recovery boiler 16 is sufficiently started up, and when the amount of generated steam is increased, the on-off valve 41 is closed and the on-off valve 18 is opened to start normal operation. I am doing so. At this time, the opening degree control of the adjusting valve 20 is performed by the control device 30 as described with reference to FIGS.
[0008]
[Problems to be solved by the invention]
As described above, when the conventional single-shaft combined power plant is started up, the amount of steam generated in the exhaust heat recovery boiler 16 immediately after startup is small, so that cooling steam is introduced from the auxiliary steam generator 40 and the wind of the steam turbine 12 at the time of startup. Temperature rise due to damage is prevented. If only the generated steam of the exhaust heat recovery boiler 16 is used without using this auxiliary steam, the control valve 20 is opened to obtain the required steam quantity, but the generated steam quantity of the exhaust heat recovery boiler 16 is delayed. The drum pressure in the boiler is lowered, and the drum level cannot be controlled. Therefore, the steam of the auxiliary steam generator 40 is used at the time of starting.
[0009]
However, a large auxiliary steam generator 40 is required outside for such startup, and the amount of steam used at startup is large, and steam generated in the exhaust heat recovery boiler 16 without using auxiliary steam. It had been strongly desired to be able to start with only before.
[0010]
Therefore, in the present invention, it has been confirmed that when the cooling steam temperature is the same at start-up, if the condenser vacuum level is improved, the metal temperature of the steam turbine is also reduced. If the degree of vacuum is good, the flow rate of the cooling steam is reduced, and if the degree of vacuum becomes worse, the amount of cooling steam is increased according to the degree of control, thereby eliminating waste of steam and eliminating the use of auxiliary steam. An object of the present invention is to provide a control valve control system for introducing steam turbine cooling steam.
[0011]
[Means for Solving the Problems]
The present invention provides the following means in order to solve the aforementioned problems.
[0012]
A steam turbine uniaxially connected to the gas turbine, a condenser for condensing the exhaust of the steam turbine, a steam pressure detector for detecting an inlet steam pressure of the steam turbine, and a steam flow rate to the steam turbine are controlled. The gas of a single-shaft combined plant comprising: a control valve that controls the control valve to input the detection pressure value of the steam pressure detector, obtain the opening of the control valve corresponding to the detection value, and control the control valve In a control valve control system for introducing cooling steam into the steam turbine when the turbine is started up; the condenser is provided with a vacuum pressure detector for detecting the degree of internal vacuum, and the control device is provided with the vacuum pressure detector. Depending on the detected value, when the degree of vacuum is higher than a predetermined value, the valve opening determined by the detected value of the steam pressure detector is throttled. Conversely, when the vacuum is low, the valve opening is adjusted. Control valve control system at the time of the steam turbine cooling steam introduction and correcting as expanding.
[0013]
When starting a single-shaft combined power plant, the steam turbine rises in temperature due to windage and requires cooling steam. However, immediately after starting the gas turbine, the amount of steam generated in the exhaust heat recovery boiler is small, so auxiliary steam from an external auxiliary steam source is required. Is used. The present invention controls the cooling steam at the start-up, and the detection value of the vacuum pressure detector of the condenser is input to the control device. The condenser guides the exhaust of the steam turbine and cools it with seawater to condense, but the degree of vacuum in the condenser varies depending on the temperature of the seawater. The seawater temperature is high in summer and low in winter, and the condenser vacuum is higher in winter when the temperature is low. When the vacuum degree of the condenser increases, the metal temperature of the steam turbine also decreases, so that the amount of cooling steam that flows in can be reduced accordingly. In the present invention, when the detection value from the vacuum pressure detector is in a high vacuum state, the control device can reduce the valve opening degree obtained from the detection value of the steam pressure detector, and the low vacuum state. If it is, it correct | amends so that the valve opening degree may be expanded, and controls a valve. Especially when the condenser is in a high vacuum state, such as in winter, the amount of cooling steam can be reduced, and even without using auxiliary steam, the cooling steam can be covered with a small amount of exhaust heat recovery boiler.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is an overall system diagram of a control valve control system when a steam turbine cooling steam is introduced according to an embodiment of the present invention. In the figure, reference numerals 11 to 21, 25, 40, and 41 are the same as those in the conventional system diagram shown in FIG. It is a part of the vacuum pressure detector of the apparatus 2 and will be described in detail below.
[0015]
In FIG. 1, reference numeral 1 denotes a control device, which is the same as the conventional control device 30 in that a detection signal from the pressure detector 21 is input and the on-off valves 18, 19, 41 and the control valve 20 are controlled. In the present invention, the vacuum pressure detector 2 for detecting the degree of vacuum in the condenser 14 is provided, and this detection signal is input to the control device 1, and the control device 1 uses the steam pressure detector P 1 at the conventional steam turbine inlet. Control is performed so as to correct the opening signal of the adjusting valve 20 based on the above.
[0016]
FIG. 2 shows the contents of the control in the control device 1 described above, (a) is a block diagram thereof, and (b) is a diagram showing an opening degree signal. In FIG. 2A, the control device 1 inputs the steam turbine inlet steam pressure signal P 1 from the pressure detector 21 as in the prior art, and the function generator 31 determines in advance according to the magnitude of the pressure signal P 1. The opening degree signal S 1 is output.
[0017]
On the other hand, the vacuum pressure P 2 in the condenser 14 is sent from the vacuum pressure detector 2 to the control device 1. If the vacuum pressure is high according to the degree of vacuum in the function generator 3, a large correction value, the degree of vacuum is low. if a small correction value, and outputs as the opening correction signal S 2. These two signals S 1 and S 2 are added by the adder 4 to output an opening signal S 3 of the adjusting valve 20.
FIG. 2B illustrates the state of this state signal. An opening signal of S 1 is output at the inlet steam pressure P 1 , and the opening degree is decreased if the degree of vacuum is high according to the degree of vacuum. , results corrected by the adder 4 by the correction opening degree signal S 2 to increase the opening a low, becomes the opening signal S 3, controls the opening of the control valve 20 as a signal in consideration of the degree of vacuum .
[0018]
FIG. 3 is a diagram showing the relationship between the low-pressure cooling steam flow (when the auxiliary steam is used and the steam temperature is 140 ° C.) and the low-pressure final stage stationary blade metal temperature, and the pressure value indicates the degree of vacuum in the condenser. . As is clear from this figure, at the time of starting the single-shaft combined power plant, it can be seen that the higher the vacuum degree of the condenser, the lower the metal temperature of the low-pressure steam turbine final stage stationary blade.
[0019]
FIG. 4 generally shows the result of FIG. 3 in relation to the degree of vacuum in the condenser and the metal temperature of the low-pressure steam turbine final stage stationary blade with the steam amount being constant. From this result, it can be seen that when the condenser vacuum level is high at startup, the metal temperature of the steam turbine decreases, and when the vacuum level is low, the metal temperature is high. Depending on the degree of vacuum, the flow rate of the cooling steam is optimally controlled, and especially when the degree of vacuum is high, the flow of cooling steam at the start-up can be reduced by preventing excessive flow of steam. .
[0020]
The vacuum level of the condenser varies depending on the temperature of the seawater led to the condenser, and the seawater temperature is high in summer and low in winter. Therefore, the degree of vacuum in the condenser tends to be high in winter when the seawater temperature is low, and in this winter, the opening signal S 1 of the adjusting valve 20 is corrected by the correction signal S 2 by the control device 1 of the present invention. small comb cooling steam flow rate as a throttle direction of opening signal S 3, it is possible also to enable activation with little steam generation amount of the exhaust heat recovery boiler 16. Therefore, the auxiliary steam device 21 does not have to be used in such a state where the degree of vacuum is good. In this case, the control device 1 performs control so that the on-off valve 41 is closed.
[0021]
According to the control valve control system at the time of introduction of the steam turbine cooling steam according to the embodiment described above, in the control of the control valve 20 at the time of introduction of the cooling steam at the time of starting the single-shaft combined power plant, the control device 1 is the inlet of the steam turbine. detecting a low-pressure steam pressure P 1, and outputs a predetermined valve opening signals S 1 corresponding from the function generator 31 to the P 1, further vacuum pressure value P from the vacuum pressure detector 2 of the condenser 14 2 enter a, from the function generator 3 outputs the opening degree correction signal S 2 corresponding to the P 2, since the S 1 and outputs a control valve opening signal S 3 by correcting with S 2 Particularly, when the degree of vacuum of the condenser 14 is high, such as in winter, the amount of cooling steam is reduced, and even a small amount of steam generated by the exhaust heat recovery boiler 16 can be started, and the auxiliary steam from the auxiliary steam generator 40 can be started. Is unnecessary.
[0022]
【The invention's effect】
A control valve control system for introducing steam turbine cooling steam according to the present invention detects a steam turbine uniaxially connected to a gas turbine, a condenser for condensing the exhaust of the steam turbine, and an inlet steam pressure of the steam turbine. A steam pressure detector for controlling the steam flow rate to the steam turbine, a detected pressure value of the steam pressure detector is input, and an opening degree of the adjusting valve corresponding to the detected value is obtained, In a control valve control system for introducing cooling steam into the steam turbine when starting the gas turbine of a single-shaft combined plant having a control device for controlling the control valve; a vacuum for detecting an internal vacuum degree in the condenser A pressure detector is provided, and the control device obtains the detection value of the vapor pressure detector according to the detection value of the vacuum pressure detector when the degree of vacuum is higher than a predetermined value. Squeezing the serial control valve opening, the at the time of low vacuum state reverse is characterized by correcting to enlarge the control valve opening. With such a system, the control device can correct the opening / closing signal of the regulating valve when the degree of vacuum is high according to the degree of vacuum of the condenser, and can reduce the amount of cooling steam by restricting the regulating valve. The amount of cooling steam may be small, and even a small amount of steam generated in the exhaust heat recovery boiler can be started up, so that auxiliary steam is unnecessary.
[Brief description of the drawings]
FIG. 1 is an overall system diagram of a control valve control system when a steam turbine cooling steam is introduced according to an embodiment of the present invention.
FIGS. 2A and 2B show control of an adjustable valve control system according to an embodiment of the present invention, where FIG. 2A is a block diagram and FIG. 2B is an explanatory diagram of signals.
FIG. 3 is a diagram showing a relationship between a cooling steam flow rate at startup and a metal temperature of a steam turbine in a single-shaft combined plant.
FIG. 4 is a diagram showing a relationship between a condenser vacuum degree and a steam turbine metal temperature in a single-shaft combined plant.
FIG. 5 is a block diagram of control for controlling the cooling steam flow rate at the time of starting the conventional single-shaft combined plant.
FIG. 6 is a diagram showing the relationship between the cooling steam pressure and the control valve opening in a conventional single-shaft combined plant.
FIG. 7 is an overall system diagram of a control valve control system when a steam turbine cooling steam is introduced in a conventional single-shaft combined plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Control apparatus 2 Vacuum pressure detector 3 Function generator 4 Adder 11 Gas turbine 12 Steam turbine 13 Generator 14 Condenser 15 Pump 16 Exhaust heat recovery boilers 18 and 41 On-off valve 19 Main on-off valve 20 Adjustment valve 21 Pressure detection 40 Auxiliary steam generator

Claims (1)

ガスタービンと一軸で連結する蒸気タービンと、同蒸気タービンの排気を復水する復水器と、前記蒸気タービンの入口蒸気圧力を検出する蒸気圧力検出器と、前記蒸気タービンへの蒸気流量を制御する加減弁と、前記蒸気圧力検出器の検出圧力値を入力し、同検出値に対応する前記加減弁の開度を求め、前記加減弁を制御する制御装置とを有する一軸コンバインドプラントの前記ガスタービン起動時に前記蒸気タービンに冷却蒸気を導入する時の加減弁制御システムにおいて；前記復水器には内部の真空度を検出する真空圧力検出器を設け、前記制御装置は同真空圧力検出器の検出値に応じて真空度が所定値よりも高真空状態の時には前記蒸気圧力検出器の検出値により求めた前記加減弁開度を絞り、逆に低真空状態の時には前記加減弁開度を拡大するように補正することを特徴とする蒸気タービン冷却蒸気導入時の加減弁制御システム。A steam turbine uniaxially connected to the gas turbine, a condenser for condensing the exhaust of the steam turbine, a steam pressure detector for detecting an inlet steam pressure of the steam turbine, and a steam flow rate to the steam turbine are controlled. The gas of a single-shaft combined plant comprising: a control valve that controls the control valve to input the detection pressure value of the steam pressure detector, obtain the opening of the control valve corresponding to the detection value, and control the control valve In a control valve control system for introducing cooling steam into the steam turbine when the turbine is started up; the condenser is provided with a vacuum pressure detector for detecting the degree of internal vacuum, and the control device is provided with the vacuum pressure detector. Depending on the detected value, when the degree of vacuum is higher than a predetermined value, the valve opening determined by the detected value of the steam pressure detector is throttled. Conversely, when the vacuum is low, the valve opening is adjusted. Control valve control system at the time of the steam turbine cooling steam introduction and correcting as expanding.
JP13976998A 1998-05-21 1998-05-21 Control valve control system when steam turbine cooling steam is introduced Expired - Lifetime JP4052405B2 (en)

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JP2001173410A (en) 1999-12-21 2001-06-26 Mitsubishi Heavy Ind Ltd Gas turbine control device for one axial type combined cycle power generation plant, and gas turbine output calculating method
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