JP4101402B2

JP4101402B2 - Exhaust heat recovery boiler and operation method of exhaust heat recovery boiler

Info

Publication number: JP4101402B2
Application number: JP17325599A
Authority: JP
Inventors: 敏美松浦; 孝幸長嶋
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1999-06-18
Filing date: 1999-06-18
Publication date: 2008-06-18
Anticipated expiration: 2019-06-18
Also published as: JP2001003711A

Description

【０００１】
【発明の属する技術分野】
本発明は、排ガス中に含まれる窒素酸化物の濃度を低く抑える排熱回収ボイラおよび排熱回収ボイラの運転方法に関する。
【０００２】
【従来の技術】
近年、高プラント熱効率、使用頻度の高さ、環境に与える悪影響の少なさ等に鑑み、ガスタービンプラントに蒸気タービンプラントを組み合せたコンバインドサイクル発電プラントが実機として火力発電プラントに数多く適用されるようになっている。
【０００３】
このコンバインドサイクル発電プラントは、燃料に硫黄酸化物の発生の少ない天然ガスを使用し、また、燃焼ガスを生成する際に窒素酸化物（ＮＯｘ）の濃度を低く抑えるガスタービン燃焼器を使用して環境汚染を少なくさせている。
【０００４】
さらに、また、このコンバインドサイクル発電プラントはガスタービンプラントに排出される排ガスを熱源として蒸気を発生させる排熱回収ボイラを設け、熱の有効活用を図ってプラント熱効率を増加させる一方、ガスタービンプラントからの排ガスに含まれるＮＯｘ濃度を低く抑える脱硝装置を排熱回収ボイラに収容させ、法律で定められた公害汚染規制値に充分に応えることができるようになっている。
【０００５】
このように、排ガスの熱有効活用を図り、ＮＯｘ濃度を低く抑えるコンバインドサイクル発電プラントに組み込まれた排熱回収ボイラは、図５に示すように、排ガス１の流れ方向に向って延びる長筒状の筒体２に、排ガスの流れに沿って順に再熱器３、高圧過熱器４、高圧ドラム５を備えた高圧蒸発器６、脱硝装置７、高圧第１節炭器８、中圧過熱器９、中圧ドラム１０を備えた中圧蒸発器１１、低圧過熱器１２、中圧節炭器１３、高圧第２節炭器１４、低圧ドラム１５を備えた低圧蒸発器１６、低圧節炭器１７、高圧第３節炭器１８を収容している。
【０００６】
また、排熱回収ボイラは、筒体２の外側にダンパ１８ａを設け、運転停止時、ダンパ１８ａを閉じ、排ガス１を筒体２内に閉じ込め、上述再熱器３、高圧過熱器４、……等の熱交換器に残っている蒸気の温度を高く維持させる、いわゆるホットバンキング運転ができるようになっている。なお、図５で示した排熱回収ボイラは、圧力が１３０ｋｇ／ｃｍ^２級の高圧ドラム５、圧力が４０ｋｇ／ｃｍ^２級の中圧ドラム１０、圧力が８ｋｇ／ｃｍ^２級の低圧ドラム１５を備えた、いわゆる３ドラム形式になっているが、ガスタービンプラントから排出される排ガスの温度如何によっては蒸気ドラムが高低圧力の複圧式の場合もある。
【０００７】
このように従来の排熱回収ボイラは、ガスタービンプラントからの排ガス１を熱源とし、高圧系の熱交換器としての再熱器３、高圧過熱器４、高圧蒸発器６に順次流れる蒸気を高圧・高温化させ、その高圧・高温蒸気を蒸気タービンプラントに供給するとともに、脱硝装置７で排ガス１に含まれるＮＯｘ濃度を低くさせ、さらに高中低圧系の熱交換器としての高圧第１節炭器８、中圧過熱器９、……等に順次流れる蒸気を昇圧・昇温させ、排ガス１の温度を約１００℃にし、ダンパ１８ａ、煙突を介して大気に放出させている。
【０００８】
【発明が解決しようとする課題】
ところで、排熱回収ボイラに収容された脱硝装置７は、その脱硝性能が触媒自身の温度に大きく依存している。触媒自身の温度と脱硝効率との関係は、図６に示すように、約２００℃まで脱硝効率が比例的に増加し、２００℃を上廻ると飽和の状態に入るようになっている。
【０００９】
この線図によれば、排ガス温度が２００℃を下廻ると、脱硝効率が低くなるから、排熱回収ボイラは、定格運転時、ＮＯｘ濃度を低く抑することができても、冷態起動、定期点検等の計画停止や強制停止によるプラント長期停止後の再起動時、排ガス１が再熱器３、高圧過熱器４、高圧蒸発器６、……等の熱交換器を通過するとき熱が奪われて排ガス１自身の温度が低くなり、設計値どおりの低いＮＯｘ濃度に維持させることができない問題点があった。
【００１０】
近年、環境に対する配慮から、排熱回収ボイラの定格運転のみならず起動運転時も含めたＮＯｘ排出濃度／排出総量等の環境規制値が設定されるプラントもあり、上述の脱硝装置７の冷態起動時におけるＮＯｘ対策が必要となっている。
【００１１】
このような問題点への具体的な対策として例えば特開昭６１−７６８０３号公報が開示されている。
【００１２】
この技術は、ドラム内の水および蒸発器内の水を循環させる間に、別の加熱源から供給された蒸気を加えてその水を加温・昇圧させ、脱硝装置を流れる排ガスの温度を高めるものである。
【００１３】
しかし、冷態起動時、ドラム等内の水は大気温度近くまで下っており、またその圧力も大気圧に近くなっており、比較的比熱の低い蒸気で比熱（熱容量）の大きいドラム水や蒸発器内の水を昇温させるには長時間を要するため、脱硝装置の昇温および脱硝効率の立上りに長時間を必要とする不具合・不都合がある。
【００１４】
本発明は、このような事情に基づいてなされたもので、冷態起動運転でも短時間で脱硝装置を加熱させてＮＯｘ濃度を低く抑えた排熱回収ボイラおよび排熱回収ボイラの運転方法を提供することを目的とする。
【００１６】
【課題を解決するための手段】
また、本発明に係る排熱回収ボイラは、上記目的を達成するために、請求項１に記載したように、筒体内に収容され、排ガスの流れに沿って順に再熱器、高圧過熱器、高圧ドラムを備えた高圧蒸発器、脱硝装置を備えた排熱回収ボイラにおいて、上記高圧ドラムに外部熱源部からの高温水を供給する高温水供給手段と、上記蒸発器に外部熱源部からの蒸気を供給する第１の蒸気供給手段と、上記再熱器に外部熱源部からの蒸気を供給する第２の蒸気供給手段とを備えたものである。
【００１７】
また、本発明に係る排熱回収ボイラは、上記目的を達成するために、請求項２に記載したように、上記高温水供給手段は、外部熱源部と高圧ドラムとを接続させる高温水供給管であることを特徴とするものである。
【００１８】
また、本発明に係る排熱回収ボイラは、上記目的を達成するために、請求項３に記載したように、上記第１の蒸気供給手段は、外部熱源部と高圧蒸発器とを接続させる高圧蒸発器ウォーミング管であることを特徴とするものである。
【００１９】
また、本発明に係る排熱回収ボイラは、上記目的を達成するために、請求項４に記載したように、上記第２の蒸気供給手段は外部熱源部と再熱器とを接続させる再熱器ウォーミング管であることを特徴とするものである。
【００２１】
また、本発明に係る排熱回収ボイラの運転方法は、上記目的を達成するために、請求項５に記載したように、ガスタービンの燃料着火前、高圧ドラムに高温水を供給するとともに、高圧蒸発器および再熱器のそれぞれに蒸気を供給して上記高圧ドラム、高圧蒸発器および再熱器のウォーミング運転を行い、次に上記ガスタービンに残留する排ガスを上記再熱器および高圧蒸発器に案内するパージ運転を行い、上記ウォーミング運転およびパージ運転で加熱された上記再熱器および高圧蒸発器から熱を奪った空気で脱硝装置を加熱する方法である。
【００２３】
【発明の実施の形態】
以下、本発明に係る排熱回収ボイラおよび蒸気の運転方法の実施形態を図面および図面に付した符号を引用して説明する。
【００２４】
図１は、本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法の第１実施形態を説明する一部切欠概略系統図である。
【００２５】
本実施形態に係る排熱回収ボイラは、長筒状の筒体１９に、排ガスＥＧの流れに沿って順に再熱器２０、高圧加熱器２１、高圧ドラム２２を備えた高圧蒸発器２３、脱硝装置２４、高圧第１節炭器２５等の熱交換器を収容している。
【００２６】
また、排熱回収ボイラは、例えば隣の排熱回収ボイラの高圧節炭器または中圧節炭器等からの高温水を連絡管２６を介して高圧ドラム２２に供給する高温水供給管２７を備えている。なお、連絡管２６は、ドラム給水弁２８を備えた高圧第１節炭器２５に接続し、高圧第１節炭器２５で発生した高温水を高圧ドラム２２に供給するようになっている。
【００２７】
また、排熱回収ボイラは、例えば隣の排熱回収ボイラの高圧ドラムから供給された蒸気のうち、一部を連絡弁２９を介して高温水供給管２７に供給するとともに、残りをウォーミング弁３０ａを備えた高圧蒸発器ウォーミング管３０を介して高圧蒸発器２３に供給する蒸気管３１を備えている。なお、高圧ドラム２２にはドラム水ブロー系３２が、高圧蒸発器２３には蒸発器ブロー弁３３が、高圧ドラム２２にはベント弁３４が、高圧過熱器２１には高圧過熱器ドレン弁３５がそれぞれ設けられている。
【００２８】
次に上記構成に基づく排熱回収ボイラの運転方法を説明する。
【００２９】
冷態起動時、高圧ドラム２２は、その内圧がほぼ大気圧に近く、またそのドラム水が大気温度に近い状態になっている。このような状態において、排熱回収ボイラは、起動運転を行うとき、まず、ドラム水をドラム水ブロー系３２を介して系外ブローし、蒸発器ブロー弁３３を開弁させて器内水を系外ブローさせた後も、蒸気管３１から供給された蒸気を連絡弁２９、高温水供給管２７、連絡管２６を介して高圧ドラム２２に供給し、高圧ドラム２２および高圧蒸発器２３にウォーミング（暖機）運転を行わせる。その際、高圧過熱器出口弁３６を閉弁させ、高圧過熱器ドレン弁３５を介弁させ、高圧過熱器２１にもウォーミング運転を行わせる。
【００３０】
ウォーミング運転終了後、排熱回収ボイラは蒸発器ブロー弁３３、ベント弁３４、高圧過熱器ドレン弁３５を閉弁させ、ドラム水ブロー系３２を閉じ、蒸気管３１から連絡弁２９、高温水供給管２７、連絡管２６を介して供給する例えば３５０℃、７ａｔａの蒸気で高圧ドラム２２および高圧蒸発器２３の内圧を高める。
【００３１】
高圧ドラム２２および高圧蒸発器２３の内圧が予め定められた圧力になると、排熱回収ボイラは連絡弁２９を閉弁させ、高温水供給管２７からの約２５０℃の高温水を高圧ドラム２２および高圧蒸発器２３に供給させ、器内に収容する高圧過熱器２１および脱硝装置２４の周辺を高温化させる。
【００３２】
高圧過熱器２１および脱硝装置２４の周辺が高温化すると、ガスタービンプラントはガスタービンの昇速回転中、例えば定格回転数の３０％で残留ガスによる爆発防止を考慮してパージ運転を行い、ガスタービン内の残留空気をパージして排熱回収ボイラに供給する。その際、パージ空気は高圧過熱器２１および高圧蒸発器２３から熱を奪って高温化し、脱硝装置２４をさらに高温化させる。なお、パージ空気により熱を奪われた高圧蒸発器２３は、ウォーミング弁３０ａを開弁させ蒸気管３１から高圧蒸発器ウォーミング管３０を介して供給される蒸気を補給すればよい。また、パージ空気により熱を奪われた高圧過熱器２１は、その器内の蒸気がドレン化した場合、高圧過熱器ドレン弁３５を適宜、開弁させてドレンを系外ブローさせればよい。
【００３３】
このように、本実施形態はウォーミング運転中およびパージ運転中に脱硝装置２４を予め高温化させているので、起動運転時の初期の段階からＮＯｘ濃度を低く抑えることができる。
【００３４】
図４は、本実施形態と従来とを対比させたガスタービン起動運転時におけるＮＯｘ濃度線図である。なお、図４中、ｒはガスタービンの回転数分布線、ｅ_１は従来の脱硝効率分布線、ｅ_２は本実施形態による脱硝効率分布線、ｇは排熱回収ボイラに供給される排ガス中に含まれるＮＯｘ濃度分布線、ｇ_１は従来の脱硝装置２４によりＮＯｘ濃度を抑制するＮＯｘ濃度抑制分布線、ｇ_２は本実施形態に係る脱硝装置によりＮＯｘ濃度を抑制するＮＯｘ濃度抑制分布線、Ｔ_１はガスタービンの燃料着火時間、Ｔ_２はガスタービン排熱回収ボイラに供給されるＮＯｘ濃度のピーク値を示す時間をそれぞれ示している。
【００３５】
従来、排熱回収ボイラは、ガスタービンの燃料着火時点Ｔ_１で生成された燃焼ガスを熱源として脱硝装置２４を加熱させていたため、ガスタービンから供給される排ガス中に含まれるＮＯｘ濃度がピーク値時点Ｔ_２になっても脱硝装置２４の脱硝効率ｅ_１が低く、ＮＯｘ濃度値ｇ_１を低く抑えることができなかった。
【００３６】
これに対し、本実施形態では、脱硝装置２４をウォーミング運転およびパージ運転中に加熱させているので、ガスタービンの燃料着火時点Ｔ_１で脱硝装置２４の脱硝効率ｅ_２が高くなっており、ＮＯｘ濃度値ｇ_２を起動運転当初から低く抑えることができるようになった。
【００３７】
したがって、本実施形態によれば、ガスタービンの起動運転当初からＮＯｘ濃度を低く抑えているので、従来、難しいとされていた起動運転当初からのＮＯｘ濃度を法律規制値以内に充分に収めることができ、環境汚染を確実に防止することができる。
【００３８】
図２は、本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法の第２実施形態を説明する一部切欠概略系統図である。なお、第１実施形態の構成部分と同一部分には同一符号を付している。
【００３９】
本実施形態に係る排熱回収ボイラおよび排熱回収ボイラの運転方法は、蒸気管３１から再熱器２０にウォーミング用としての蒸気を供給するウォーミング弁３７ａを備えた再熱器ウォーミング管３７を設けるとともに、再熱器２０をウォーミングさせたドレンを系外ブローさせる再熱器ドレン弁３８を設け、再熱器２０を常に高温状態に維持させたものである。
【００４０】
また、本実施形態に係る排熱回収ボイラおよび排熱回収ボイラの運転方法は、ウォーミング運転中およびパージ運転中、脱硝装置２４を加熱させる空気が再熱器２０で熱を奪うことを考慮したもので、蒸気管３１から分岐し、再熱器２０に接続する再熱器ウォーミング管３７を設け、常時、再熱器２０に蒸気を供給し、再熱器２０を高温状態に維持させたものである。
【００４１】
このように、本実施形態では、常時、再熱器２０を高温状態に維持させているので、器内を流れる空気をより早く高温化させて脱硝装置２４を比較的短時間で加熱させることができ、起動運転時でも高い脱硝効率の下、ＮＯｘ濃度を低く抑えることができる。
【００４２】
図３は、本発明に係る排熱回収ボイラの運転方法の第３実施形態を説明する一部切欠概略系統図である。なお、第１実施形態の構成部分と同一部分には同一符号を付している。
【００４３】
本実施形態に係る排熱回収ボイラの運転方法は、筒体１９の下流側に収容され、排ガスＥＧの流れに沿って順に、低圧ドラム３９を備えた低圧蒸発器４０、低圧節炭器４１、高圧第３節炭器４２を設置した、その高圧第３節炭器４２の外側に設けたダンパ４３をパージ運転中に開口し、トンネル効果を利用し筒内の空気を強制的に流し、脱硝装置２４を加熱させたものである。実測によれば、ガスタービンの回転数が１００ｒｐｍでもダンパ４３が開口していると、筒体１９内の空気はトンネル効果により流れることが認められた。
【００４４】
このように、本実施形態では、パージ運転中、ダンパ４３を開口させ、筒体１９内の空気を強制的に流し脱硝装置２４を加熱させるので、起動運転時でも高い脱硝効率の下、ＮＯｘ濃度を低く抑えることができる。
【００４５】
【発明の効果】
以上説明のとおり、本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法は、ウォーミング運転およパージ運転で加熱させた熱交換器から奪った熱で空気を加熱させ、その加熱した空気で脱硝装置を加熱させるので、起動運転時でも高い脱硝効率の下、ＮＯｘ濃度を低く抑えることができる。
【図面の簡単な説明】
【図１】本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法の第１実施形態を説明する一部切欠概略系統図。
【図２】本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法の第２実施形態を説明する一部切欠概略系統図。
【図３】本発明に係る排熱回収ボイラの運転方法の第３実施形態を説明する一部切欠概略系統図。
【図４】本発明に係る排熱回収ボイラおよび排熱回収ボイラの運転方法と従来とを対比させたガスタービン起動運転時におけるＮＯｘ濃度線図。
【図５】従来の排熱回収ボイラを示す概略系統図。
【図６】脱硝装置の温度に対する脱硝効率を示す脱硝効率分布線図。
【符号の説明】
１排ガス
２筒体
３再熱器
４高圧過熱器
５高圧ドラム
６高圧蒸発器
７脱硝装置
８高圧第１節炭器
９中圧過熱器
１０中圧ドラム
１１中圧蒸発器
１２低圧過熱器
１３中圧節炭器
１４高圧第２節炭器
１５低圧ドラム
１６低圧蒸発器
１７低圧節炭器
１８高圧第３節炭器
１８ａダンパ
１９筒体
２０再熱器
２１高圧過熱器
２２高圧ドラム
２３高圧蒸発器
２４脱硝装置
２５高圧第１節炭器
２６連絡管
２７高温水供給管
２８ドラム給水弁
２９連絡弁
３０高圧蒸発器ウォーミング管
３０ａウォーミング弁
３１蒸発管
３２ドラム水ブロー系
３３蒸発器ブロー弁
３４ベント弁
３５高圧過熱器ドレン弁
３６高圧過熱器出口弁
３７再熱器ウォーミング管
３７ａウォーミング弁
３８再熱器ドレン弁
３９低圧ドラム
４０低圧蒸発器
４１低圧節炭器
４２高圧第３節炭器
４３ダンパ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust heat recovery boiler that suppresses the concentration of nitrogen oxides contained in exhaust gas and a method for operating the exhaust heat recovery boiler.
[0002]
[Prior art]
In recent years, in view of high plant thermal efficiency, high frequency of use, and low adverse effects on the environment, a combined cycle power plant that combines a gas turbine plant with a steam turbine plant has been applied to many thermal power plants as actual machines. It has become.
[0003]
This combined cycle power plant uses natural gas with low generation of sulfur oxide as fuel, and uses a gas turbine combustor that keeps the concentration of nitrogen oxide (NOx) low when generating combustion gas. Reduces environmental pollution.
[0004]
Furthermore, this combined cycle power plant is provided with a waste heat recovery boiler that generates steam using the exhaust gas discharged to the gas turbine plant as a heat source to increase the heat efficiency of the plant by effectively using heat, while from the gas turbine plant. A NOx removal device for reducing the NOx concentration contained in the exhaust gas is housed in an exhaust heat recovery boiler so that it can fully meet the pollution pollution control values stipulated by law.
[0005]
In this way, the exhaust heat recovery boiler incorporated in the combined cycle power plant that effectively uses the heat of the exhaust gas and keeps the NOx concentration low, as shown in FIG. 5, is a long cylindrical shape that extends in the flow direction of the exhaust gas 1. A high-pressure evaporator 6 having a reheater 3, a high-pressure superheater 4, a high-pressure drum 5, a denitration device 7, a high-pressure first economizer 8, and an intermediate-pressure superheater 9. Medium pressure evaporator 11 with medium pressure drum 10, low pressure superheater 12, medium pressure economizer 13, high pressure second economizer 14, low pressure evaporator 16 with low pressure drum 15, low pressure economizer 17. A high-pressure third economizer 18 is accommodated.
[0006]
Further, the exhaust heat recovery boiler is provided with a damper 18a outside the cylinder 2, and when the operation is stopped, the damper 18a is closed, the exhaust gas 1 is confined in the cylinder 2, and the reheater 3, the high pressure superheater 4,. The so-called hot banking operation that keeps the temperature of the steam remaining in the heat exchanger such as. Incidentally, the heat recovery boiler shown in Figure 5, a high pressure drum 5 the pressure of 130 kg / cm ² grade, pressure drum 10 in a pressure 40 kg / cm ² grade, the pressure 8 kg / cm ² grade of the low-pressure drum 15 The so-called three-drum type is provided, but depending on the temperature of the exhaust gas discharged from the gas turbine plant, the steam drum may be a high-low pressure double-pressure type.
[0007]
As described above, the conventional exhaust heat recovery boiler uses the exhaust gas 1 from the gas turbine plant as a heat source, and the steam that sequentially flows to the reheater 3, the high-pressure superheater 4, and the high-pressure evaporator 6 as a high-pressure heat exchanger.・ High temperature, supply high-pressure / high-temperature steam to the steam turbine plant, reduce NOx concentration contained in the exhaust gas 1 with the denitration device 7, and further, a high-pressure first economizer as a high, medium and low pressure heat exchanger 8, the pressure of the steam that sequentially flows to the intermediate pressure superheater 9,... Is increased and the temperature of the exhaust gas 1 is set to about 100 ° C., and is released to the atmosphere through the damper 18a and the chimney.
[0008]
[Problems to be solved by the invention]
By the way, the denitration device 7 accommodated in the exhaust heat recovery boiler greatly depends on the temperature of the catalyst itself for the denitration performance. As shown in FIG. 6, the relationship between the temperature of the catalyst itself and the denitration efficiency is such that the denitration efficiency increases proportionally up to about 200 ° C., and enters a saturation state when the temperature exceeds 200 ° C.
[0009]
According to this diagram, when the exhaust gas temperature is lower than 200 ° C., the denitration efficiency is lowered. Therefore, even if the exhaust heat recovery boiler can keep the NOx concentration low during rated operation, When the exhaust gas 1 passes through a heat exchanger such as the reheater 3, high pressure superheater 4, high pressure evaporator 6,. As a result, the temperature of the exhaust gas 1 itself is lowered, and there is a problem in that it cannot be maintained at a low NOx concentration as designed.
[0010]
In recent years, in consideration of the environment, there are also plants in which environmental regulation values such as NOx emission concentration / total emission amount including not only rated operation but also startup operation of the exhaust heat recovery boiler are set. It is necessary to take measures against NOx at startup.
[0011]
For example, Japanese Patent Application Laid-Open No. 61-76803 is disclosed as a specific countermeasure for such a problem.
[0012]
In this technology, while circulating the water in the drum and the water in the evaporator, steam supplied from another heating source is added to warm and pressurize the water, and the temperature of the exhaust gas flowing through the denitration device is increased. Is.
[0013]
However, at the time of cold start, the water in the drum, etc. has dropped to near atmospheric temperature, and the pressure is also close to atmospheric pressure, so the drum water and evaporation with relatively low specific heat and high specific heat (heat capacity). Since it takes a long time to raise the temperature of the water in the vessel, there are problems and inconveniences that require a long time to raise the temperature of the denitration device and to increase the denitration efficiency.
[0014]
The present invention has been made based on such circumstances, and provides an exhaust heat recovery boiler in which a NOx concentration is kept low by heating a denitration apparatus in a short time even in a cold start operation, and an operation method of the exhaust heat recovery boiler The purpose is to do.
[0016]
[Means for Solving the Problems]
Moreover, in order to achieve the said objective, the waste heat recovery boiler which concerns on this invention is accommodated in a cylinder as described in Claim 1 , and a reheater, a high pressure superheater in order along the flow of waste gas, In a high-pressure evaporator equipped with a high-pressure drum, a waste heat recovery boiler equipped with a denitration device, high-temperature water supply means for supplying high-temperature water from an external heat source to the high-pressure drum, and steam from an external heat source to the evaporator And a second steam supply means for supplying the reheater with steam from an external heat source section.
[0017]
Further, the exhaust heat recovery boiler according to the present invention, in order to achieve the above object, as described in claim 2, said hot water supply means, the hot water supply pipe for connecting the the high-pressure drum external heat source unit It is characterized by being.
[0018]
Further, the exhaust heat recovery boiler according to the present invention, in order to achieve the above object, as described in claim 3, said first steam supply means so as to connect the external heat source unit and the high-pressure evaporator pressure It is an evaporator warming tube.
[0019]
Further, the exhaust heat recovery boiler according to the present invention, in order to achieve the above object, as described in claim 4, reheat the second steam supply means for connecting the external heat source unit and the reheater It is a device warming tube.
[0021]
Further, the method of operating the exhaust heat recovery boiler according to the present invention, in order to achieve the above object, as described in claim 5, before the fuel ignition of the gas turbine, supplies the hot water to the high-pressure drum, high-pressure Steam is supplied to each of the evaporator and the reheater to warm the high pressure drum, the high pressure evaporator and the reheater, and then the exhaust gas remaining in the gas turbine is removed from the reheater and the high pressure evaporator. The denitration apparatus is heated with air deprived of heat from the reheater and the high-pressure evaporator heated in the warming operation and purge operation.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an exhaust heat recovery boiler and a steam operating method according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.
[0024]
FIG. 1 is a partially cutaway schematic system diagram illustrating a first embodiment of an exhaust heat recovery boiler and an operation method of an exhaust heat recovery boiler according to the present invention.
[0025]
The exhaust heat recovery boiler according to the present embodiment includes a long cylinder 19 and a high pressure evaporator 23 including a reheater 20, a high pressure heater 21, and a high pressure drum 22 in order along the flow of the exhaust gas EG. A heat exchanger such as the device 24 and the high-pressure first economizer 25 is accommodated.
[0026]
In addition, the exhaust heat recovery boiler includes a high temperature water supply pipe 27 that supplies high temperature water from, for example, a high pressure economizer or an intermediate pressure economizer of the adjacent exhaust heat recovery boiler to the high pressure drum 22 via the connection pipe 26. I have. The connecting pipe 26 is connected to a high-pressure first economizer 25 provided with a drum water supply valve 28, and supplies high-temperature water generated by the high-pressure first economizer 25 to the high-pressure drum 22.
[0027]
The exhaust heat recovery boiler, for example, supplies a part of the steam supplied from the high-pressure drum of the adjacent exhaust heat recovery boiler to the high-temperature water supply pipe 27 via the communication valve 29 and the remaining warming valve. A vapor pipe 31 is provided to supply to the high-pressure evaporator 23 via the high-pressure evaporator warming pipe 30 provided with 30a. The high-pressure drum 22 has a drum water blow system 32, the high-pressure evaporator 23 has an evaporator blow valve 33, the high-pressure drum 22 has a vent valve 34, and the high-pressure superheater 21 has a high-pressure superheater drain valve 35. Each is provided.
[0028]
Next, an operation method of the exhaust heat recovery boiler based on the above configuration will be described.
[0029]
At the time of cold start, the high-pressure drum 22 is in a state where its internal pressure is close to atmospheric pressure and its drum water is close to atmospheric temperature. In such a state, when performing the start-up operation, the exhaust heat recovery boiler first blows the drum water out of the system through the drum water blow system 32 and opens the evaporator blow valve 33 to supply the internal water. Even after the outside blow, the steam supplied from the steam pipe 31 is supplied to the high-pressure drum 22 through the communication valve 29, the high-temperature water supply pipe 27, and the communication pipe 26, and the high-pressure drum 22 and the high-pressure evaporator 23 are warped. Ming (warm-up) operation. At that time, the high-pressure superheater outlet valve 36 is closed, the high-pressure superheater drain valve 35 is interposed, and the high-pressure superheater 21 is also warmed.
[0030]
After the warming operation is completed, the exhaust heat recovery boiler closes the evaporator blow valve 33, the vent valve 34, and the high pressure superheater drain valve 35, closes the drum water blow system 32, connects the steam pipe 31 to the communication valve 29, and hot water. The internal pressures of the high-pressure drum 22 and the high-pressure evaporator 23 are increased by, for example, steam at 350 ° C. and 7 ata supplied through the supply pipe 27 and the communication pipe 26.
[0031]
When the internal pressures of the high-pressure drum 22 and the high-pressure evaporator 23 reach predetermined pressures, the exhaust heat recovery boiler closes the communication valve 29 and supplies high-temperature water of about 250 ° C. from the high-temperature water supply pipe 27 to the high-pressure drum 22 and The high pressure evaporator 23 is supplied, and the periphery of the high pressure superheater 21 and the denitration device 24 accommodated in the chamber is heated.
[0032]
When the surroundings of the high-pressure superheater 21 and the denitration device 24 are heated, the gas turbine plant performs a purge operation in consideration of prevention of explosion due to residual gas at, for example, 30% of the rated rotation speed during the gas turbine's ascending rotation. The residual air in the turbine is purged and supplied to the exhaust heat recovery boiler. At that time, the purge air takes heat from the high-pressure superheater 21 and the high-pressure evaporator 23 to increase the temperature, and the denitration device 24 is further increased in temperature. The high pressure evaporator 23 deprived of heat by the purge air may be replenished with the steam supplied from the steam pipe 31 through the high pressure evaporator warming pipe 30 by opening the warming valve 30a. Further, the high pressure superheater 21 deprived of heat by the purge air may open the high pressure superheater drain valve 35 appropriately to blow the drain out of the system when the steam in the container is drained.
[0033]
Thus, in this embodiment, since the denitration device 24 is preliminarily heated during the warming operation and the purge operation, the NOx concentration can be kept low from the initial stage during the start-up operation.
[0034]
FIG. 4 is a NOx concentration diagram at the time of gas turbine start-up operation in which the present embodiment is compared with the conventional one. In FIG. 4, r is a rotational speed distribution line of the gas turbine, e ₁ is a conventional denitration efficiency distribution line, e ₂ is a denitration efficiency distribution line according to the present embodiment, and g is in the exhaust gas supplied to the exhaust heat recovery boiler. Included in the NOx concentration distribution line, g ₁ is a NOx concentration suppression distribution line that suppresses the NOx concentration by the conventional denitration device 24, and g ₂ is a NOx concentration suppression distribution line that suppresses the NOx concentration by the denitration device according to the present embodiment, T ₁ is the fuel ignition time of the gas turbine, T ₂ are respectively the time indicating the peak value of NOx concentration supplied to the gas turbine exhaust heat recovery boiler.
[0035]
Conventionally, heat recovery steam generator, because it was allowed to heat the denitrator 24 combustion gas generated in the fuel ignition time T ₁ of the gas turbine as a heat source, a peak value NOx concentration in the exhaust gas supplied from the gas turbine even if the time _{T 2} low denitration efficiency _{e 1} of the denitration apparatus 24, could not suppress the NOx concentration value _{g 1.}
[0036]
In contrast, in the present embodiment, since the heated denitration apparatus 24 during warming operation and the purge operation, it has a higher NOx removal efficiency e ₂ of the denitration apparatus 24 by the fuel ignition time T ₁ of the gas turbine, it has become possible to suppress the NOx concentration value g ₂ from starting operation initially.
[0037]
Therefore, according to the present embodiment, the NOx concentration is kept low from the beginning of the start-up operation of the gas turbine, so that the NOx concentration from the start of the start-up operation, which has conventionally been considered difficult, can be sufficiently kept within the legal regulation value. And environmental pollution can be surely prevented.
[0038]
FIG. 2 is a partially cutaway schematic system diagram illustrating a second embodiment of the exhaust heat recovery boiler and the operation method of the exhaust heat recovery boiler according to the present invention. In addition, the same code | symbol is attached | subjected to the same part as the component of 1st Embodiment.
[0039]
The exhaust heat recovery boiler and the operation method of the exhaust heat recovery boiler according to the present embodiment are a reheater warming pipe provided with a warming valve 37a for supplying steam for warming from the steam pipe 31 to the reheater 20. 37 and a reheater drain valve 38 for blowing the drain warmed by the reheater 20 out of the system, and the reheater 20 is always maintained at a high temperature.
[0040]
Further, the operation method of the exhaust heat recovery boiler and the exhaust heat recovery boiler according to the present embodiment takes into consideration that the air that heats the denitration device 24 takes heat away from the reheater 20 during the warming operation and the purge operation. Therefore, a reheater warming pipe 37 branched from the steam pipe 31 and connected to the reheater 20 is provided, and steam is constantly supplied to the reheater 20 to keep the reheater 20 in a high temperature state. Is.
[0041]
Thus, in this embodiment, since the reheater 20 is always maintained in a high temperature state, the air flowing in the device can be heated to a higher temperature to heat the denitration device 24 in a relatively short time. In addition, the NOx concentration can be kept low with high denitration efficiency even during start-up operation.
[0042]
FIG. 3 is a partially cutaway schematic system diagram illustrating a third embodiment of the method for operating the exhaust heat recovery boiler according to the present invention. In addition, the same code | symbol is attached | subjected to the same part as the component of 1st Embodiment.
[0043]
The operation method of the exhaust heat recovery boiler according to the present embodiment is accommodated in the downstream side of the cylindrical body 19, and in order along the flow of the exhaust gas EG, the low-pressure evaporator 40 having the low-pressure drum 39, the low-pressure economizer 41, A high-pressure third economizer 42 is installed, and a damper 43 provided outside the high-pressure third economizer 42 is opened during the purge operation, and the air in the cylinder is forced to flow using the tunnel effect to remove the denitration. The device 24 is heated. According to actual measurements, it was recognized that the air in the cylinder 19 flows due to the tunnel effect when the damper 43 is open even when the rotational speed of the gas turbine is 100 rpm.
[0044]
As described above, in the present embodiment, during the purge operation, the damper 43 is opened, the air in the cylinder 19 is forced to flow and the denitration device 24 is heated, so that the NOx concentration is also maintained under high denitration efficiency even during the start-up operation. Can be kept low.
[0045]
【The invention's effect】
As described above, the operation method of the exhaust heat recovery boiler and the exhaust heat recovery boiler according to the present invention heats the air with the heat taken from the heat exchanger heated in the warming operation and the purge operation, and heats the air. Since the denitration device is heated with air, the NOx concentration can be kept low with high denitration efficiency even during start-up operation.
[Brief description of the drawings]
FIG. 1 is a partially cutaway schematic system diagram illustrating a first embodiment of an exhaust heat recovery boiler and an operation method of an exhaust heat recovery boiler according to the present invention.
FIG. 2 is a partially cutaway schematic system diagram illustrating a second embodiment of an exhaust heat recovery boiler and an operation method of the exhaust heat recovery boiler according to the present invention.
FIG. 3 is a partially cutaway schematic system diagram illustrating a third embodiment of a method for operating an exhaust heat recovery boiler according to the present invention.
FIG. 4 is a NOx concentration diagram at the time of gas turbine start-up operation in which the exhaust heat recovery boiler according to the present invention and the operation method of the exhaust heat recovery boiler are compared with the conventional one.
FIG. 5 is a schematic system diagram showing a conventional exhaust heat recovery boiler.
FIG. 6 is a denitration efficiency distribution diagram showing the denitration efficiency with respect to the temperature of the denitration apparatus.
[Explanation of symbols]
1 exhaust gas 2 cylinder 3 reheater 4 high pressure superheater 5 high pressure drum 6 high pressure evaporator 7 denitration device 8 high pressure first economizer 9 medium pressure superheater 10 intermediate pressure drum 11 intermediate pressure evaporator 12 low pressure superheater 13 Pressure-saving economizer 14 High-pressure second economizer 15 Low-pressure drum 16 Low-pressure evaporator 17 Low-pressure economizer 18 High-pressure third economizer 18 a Damper 19 Cylindrical body 20 Reheater 21 High-pressure superheater 22 High-pressure drum 23 High-pressure evaporator 24 Denitration device 25 High pressure first economizer 26 Communication pipe 27 High temperature water supply pipe 28 Drum water supply valve 29 Communication valve 30 High pressure evaporator warming pipe 30a Warming valve 31 Evaporation pipe 32 Drum water blow system 33 Evaporator blow valve 34 Vent valve 35 High pressure superheater drain valve 36 High pressure superheater outlet valve 37 Reheater warming pipe 37a Warming valve 38 Reheater drain valve 39 Low pressure drum 40 Low pressure evaporator 41 Low pressure coal saving 42 high-pressure third economizer 43 damper

Claims

筒体内に収容され、排ガスの流れに沿って順に再熱器、高圧過熱器、高圧ドラムを備えた高圧蒸発器、脱硝装置を備えた排熱回収ボイラにおいて、上記高圧ドラムに外部熱源部からの高温水を供給する高温水供給手段と、上記蒸発器に外部熱源部からの蒸気を供給する第１の蒸気供給手段と、上記再熱器に外部熱源部からの蒸気を供給する第２の蒸気供給手段とを備えたことを特徴とする排熱回収ボイラ。 A reheater, a high-pressure superheater, a high-pressure evaporator equipped with a high-pressure drum, and an exhaust heat recovery boiler equipped with a denitration device, which are housed in a cylinder and sequentially flow along the flow of exhaust gas. High temperature water supply means for supplying high temperature water, first steam supply means for supplying steam from the external heat source section to the evaporator, and second steam for supplying steam from the external heat source section to the reheater An exhaust heat recovery boiler comprising a supply means.

上記高温水供給手段は、外部熱源部と高圧ドラムとを接続させる高温水供給管であることを特徴とする請求項１記載の排熱回収ボイラ。 2. The exhaust heat recovery boiler according to claim 1 , wherein the high temperature water supply means is a high temperature water supply pipe for connecting an external heat source section and a high pressure drum.

上記第１の蒸気供給手段は、外部熱源部と高圧蒸発器とを接続させる高圧蒸発器ウォーミング管であることを特徴とする請求項１記載の排熱回収ボイラ。 2. The exhaust heat recovery boiler according to claim 1, wherein the first steam supply means is a high-pressure evaporator warming pipe that connects the external heat source unit and the high-pressure evaporator.

上記第２の蒸気供給手段は外部熱源部と再熱器とを接続させる再熱器ウォーミング管であることを特徴とする請求項１記載の排熱回収ボイラ。 Said second steam supply means heat recovery boiler according to claim 1, characterized in that a reheater warming tube for connecting the external heat source unit and the reheater.

ガスタービンの燃料着火前、高圧ドラムに高温水を供給するとともに、高圧蒸発器および再熱器のそれぞれに蒸気を供給して上記高圧ドラム、高圧蒸発器および再熱器のウォーミング運転を行い、次に上記ガスタービンに残留する排ガスを上記再熱器および高圧蒸発器に案内するパージ運転を行い、上記ウォーミング運転およびパージ運転で加熱された上記再熱器および高圧蒸発器から熱を奪った空気で脱硝装置を加熱することを特徴とする排熱回収ボイラの運転方法。 Before the fuel ignition of the gas turbine, high-temperature water is supplied to the high-pressure drum, and steam is supplied to each of the high-pressure evaporator and the reheater to perform the warming operation of the high-pressure drum, the high-pressure evaporator, and the reheater. Next, a purge operation for guiding the exhaust gas remaining in the gas turbine to the reheater and the high pressure evaporator was performed, and heat was taken from the reheater and the high pressure evaporator heated in the warming operation and the purge operation. An operation method of an exhaust heat recovery boiler, wherein the denitration apparatus is heated with air.