JP3722928B2

JP3722928B2 - Waste heat recovery boiler unit

Info

Publication number: JP3722928B2
Application number: JP31169796A
Authority: JP
Inventors: 嶋孝幸長
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1996-11-22
Filing date: 1996-11-22
Publication date: 2005-11-30
Anticipated expiration: 2016-11-22
Also published as: JPH10153301A

Description

【０００１】
【発明の属する技術分野】
本発明はコンバインドサイクル発電プラントにおける排熱回収ボイラ装置に関する。
【０００２】
【従来の技術】
近年、発電プラントは高効率の達成が可能で、環境対策の面でも優れているコンバインドサイクル発電プラントが多く建設されている。このコンバインドサイクル発電プラントの主要な原動機であるガスタービンは大形化しており、高効率を得るために入口温度の高温化が進んでいる。このガスタービンの大形化および高温化に伴い、排熱回収ボイラは複圧式、３圧式のものが用いられ、再熱式排熱回収ボイラと蒸気タービンとからなる再熱サイクルで構成されるプラントも採用されるようになってきている。
【０００３】
図５を参照して従来技術の一例を説明する。コンバインドサイクル発電プラントはガスタービン装置１および蒸気タービン２の双方の出力によって発電機３を駆動する。排熱回収ボイラ４の熱源にはガスタービン装置１の排ガスが用いられ、蒸気タービン２には排熱回収ボイラ４で生じた蒸気が導入される。ガスタービン装置１は圧縮機で空気を圧縮し、これに燃料を混合して燃焼させ、約１３００℃の燃焼ガスを得て、これを膨張させて動力を発生させる。
【０００４】
ガスタービン装置１で仕事を終えた燃焼ガスは排ガスとして排熱回収ボイラ４に導かれる。この排ガスの温度は約６００℃の高温で二次過熱器５、二次再熱器６、一次再熱器７、一次過熱器８、高圧蒸発器９、中圧過熱器１１、高圧節炭器１２、中圧蒸発器１３の各管群を通り、さらに図示しない中圧節炭器および低圧節炭器を経て約１００℃のガスとして大気中に排出される。
【０００５】
排熱回収ボイラ４には高圧蒸発器９と結ばれる高圧ドラム１０および中圧蒸発器１３と結ばれる中圧ドラム１４が備えられ、高圧ドラム１０の給水が高圧蒸発器９に、中圧ドラム１４の給水が中圧蒸発器１３に導かれて先に述べた排ガスによって加熱され、蒸気タービン２の駆動用蒸気が発生する。高圧蒸発器９で発生した高圧の蒸気は高圧ドラム１０で気水分離された後、一次過熱器８において過熱蒸気とするために加熱される。この過熱蒸気は減温器１５でスプレー水と混合されて二次過熱器５出口蒸気温度が設定温度になるように調節され、二次過熱器５を通って主蒸気管１６から蒸気タービン２の高圧部に供給される。
【０００６】
蒸気タービン２で膨張した蒸気は低温再熱蒸気管１７を通して一次再熱器７に導かれる。途中、この蒸気は中圧過熱器１１の出口蒸気と混合されて一次再熱器７に流入する。加熱されて温度上昇した再熱蒸気は減温器１８でスプレー水と混合されて二次再熱器６出口蒸気温度が設定温度になるように調節された後、二次再熱器６を通って高温再熱蒸気管１９から蒸気タービン２の中圧部に供給される。
【０００７】
【発明が解決しようとする課題】
ところで、次世代の大容量コンバインドサイクル発電プラントにおいてはガスタービンの入口温度が１３００℃からより高温になる。このガスタービンを用いる蒸気タービンの高圧主蒸気圧力および温度はこれまで以上に高くなり、プラント効率も５０％を超えることも十分に可能になる。しかし、この高温、高圧の蒸気条件でプラント効率を達成しようとすると、蒸気タービン２の排気温度、すなわち低温再熱蒸気温度が従来の約３５０℃から約３９０℃程度に上昇し、中圧過熱器１１出口蒸気と混合させるとき、双方の蒸気の温度差が従来の２０〜３０℃から８０〜９０℃に上昇してしまう。この場合、双方の蒸気が合流する部分の配管等に過大な熱応力が生じ、機器寿命が大きく損なわれる可能性がある。
【０００８】
そこで、本発明の目的は低温再熱蒸気と中圧過熱器出口蒸気との温度差を可能な限り少なくして蒸気合流部で配管等に過大な熱応力が生じるのを防止するようにした排熱回収ボイラ装置を提供することにある。
【０００９】
【課題を解決するための手段】
第１の発明は、排ガスの流動域に、その上流側から順に高圧二次過熱器、二次再熱器、一次再熱器、高圧一次過熱器を備えるとともに、前記各熱交換器に加え中圧蒸発器、高圧蒸発器および中圧過熱器を備え、前記中圧蒸発器で発生した蒸気が前記中圧過熱器を通して加熱されると共に、蒸気タービンの高圧部から導かれる低温再熱蒸気と混合されて前記一次再熱器および二次再熱器を順次通して加熱され、該蒸気タービンの中圧部にかけて供給されるようにした排熱回収ボイラ装置において、前記中圧過熱器を該高圧蒸発器より上流側の約４７０℃の排ガスが流れる排ガス流動域に配置し、該中圧過熱器出口蒸気が前記蒸気タービンからの約３９０℃となる低温再熱蒸気とほぼ同じ温度域に加熱されるようにしたことを特徴とする。
【００１０】
さらに、第２の発明は、排ガスの流動域に、その上流側から順に高圧二次過熱器、二次再熱器、一次再熱器、高圧一次過熱器を備えるとともに、前記各熱交換器に加え中圧蒸発器、高圧蒸発器および中圧過熱器を備え、前記中圧蒸発器で発生した蒸気が前記中圧過熱器を通して加熱されると共に、蒸気タービンの高圧部から導かれる低温再熱蒸気と混合されて前記一次再熱器および二次再熱器を順次通して加熱され、該蒸気タービンの中圧部にかけて供給されるようにした排熱回収ボイラ装置において、前記高圧蒸発器の管群を２分割し、前記中圧過熱器を分割した２つの蒸発器の間の約４００℃の排ガスが流れる排ガス流動域に配置し、該中圧過熱器出口蒸気が前記蒸気タービンからの約３９０℃となる低温再熱蒸気とほぼ同じ温度域に加熱されるようにしたことを特徴とする。
【００１１】
また、第３の発明は中圧過熱器の出口側経路にあって中圧過熱器出口蒸気にスプレー水を混合する減温器と、減温器内に注入されるスプレー水量を調節する調節弁と、検出された低温再熱蒸気温度と設定温度との偏差に基づいて調節弁の開度を調節する制御信号を出力する温度制御手段とを備えることを特徴とするものである。
【００１２】
さらに、第４の発明は、排ガスの流動域に、その上流側から順に高圧二次過熱器、二次再熱器、一次再熱器、高圧一次過熱器を備えるとともに、前記各熱交換器に加え中圧蒸発器、高圧蒸発器および中圧過熱器を備え、前記中圧蒸発器で発生した蒸気が前記中圧過熱器を通して加熱されると共に、蒸気タービンの高圧部から導かれる低温再熱蒸気と混合されて前記一次再熱器および二次再熱器を順次通して加熱され、該蒸気タービンの中圧部にかけて供給されるようにした排熱回収ボイラ装置において、該蒸気タービンからの低温再熱蒸気にスプレー水を混合する減温器と、前記減温器に注入されるスプレー水量を調節する調節弁と、検出された該中圧過熱器出口蒸気温度に基づいて該調節弁の開度を調節する制御信号を出力する温度制御手段とを備えることを特徴とする。
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して説明する。なお、図において従来技術により説明された構成には図５で用いた符号と同一の符号を付しており、これらの詳細な説明は省略する。図１において、ガスタービン装置１から流出する高温の排ガスが導入される排熱回収ボイラ４は、排ガス流動域に縦列に並ぶ高圧二次過熱器５、二次再熱器６、一次再熱器７、高圧一次過熱器８、中圧過熱器１１、高圧蒸発器９、高圧節炭器１２および中圧蒸発器１３を備えている。すなわち、中圧過熱器１１は高圧蒸発器９より上流側の約４７０℃の排ガスが流れる排ガス流動域に配置されており、中圧過熱器１１の伝熱管内を流動する蒸気が上記約４７０℃の排ガスによって約３９０℃の温度に加熱されるようになっている。
【００１４】
本実施の形態は上記構成からなり、プラントの始動によりガスタービン装置１から排ガスが排熱回収ボイラ４に流入し、その入口温度が上昇する。高圧ドラム１０から高圧蒸発器９にかけて給水が流れ、排ガスによって加熱されて蒸気が発生する。この蒸気は高圧一次過熱器８および高圧二次過熱器５を通って約５４０℃の温度に過熱される。そして、主蒸気管１６を通って蒸気タービン２に流入する。
蒸気タービン２に流入した蒸気は蒸気タービン２内で膨張して圧力、温度が降下する。上記蒸気タービン２内で仕事を行い約３９０℃となった蒸気は低温再熱蒸気管１７に流れ、再び排ガスとの熱交換のために一次再熱器７にかけて流動する。
【００１５】
一方、低圧ドラム１４から中圧蒸発器１３にかけて給水が流れ、排ガスによって加熱されて主蒸気よりも圧力が低い中圧蒸気が発生する。この中圧蒸気は高圧蒸発器９より上流側の約４７０℃の排ガスが流れる排ガス流動域に設けられている中圧過熱器１１を通って約３９０℃の温度に加熱される。
【００１６】
この中圧過熱器１１出口蒸気は低温再熱蒸気管１７内を流れる約３９０℃の低温再熱蒸気と混合されて共に一次再熱器７にかけて流動する。この後、一次再熱器７に流れた低温再熱蒸気は排ガスにより加熱され、減温器１８で二次再熱器６出口蒸気温度が５４０℃になるように調節された後、蒸気タービン２に流入する。
【００１７】
このように本実施の形態によれば、中圧過熱器１１出口蒸気を低温再熱蒸気とほぼ同じ温度水準に保持することができ、蒸気の合流部において配管等に温度差に起因する過大な熱応力が生じるのを防ぐことが可能になる。
【００１８】
さらに、本発明の他の実施の形態を図２を参照して説明する。本実施の形態の高圧蒸発器２０は２分割された第１蒸発器２１と第２蒸発器２２とからなる。この第１蒸発器２１と第２蒸発器２２との間に中圧過熱器１１が配置されている。上記した点以外は図１の排熱回収ボイラ４と同一である。
【００１９】
本実施の形態は上記構成からなり、給水が中圧蒸発器１３に流れ、そこで排ガスによって加熱され、中圧蒸気が発生する。この中圧蒸気は約４００℃の排ガスが流れる中圧過熱器１１を通って約３９０℃の温度に加熱される。
【００２０】
この約４００℃の排ガスで加熱される中圧過熱器１１は排ガス温度の低下により比較的安価な炭素鋼からなる伝熱管を使用することが可能になる。すなわち、上記実施の形態においては中圧過熱器１１が約４７０℃の排ガス中に置かれ、空だき運転なども考慮すると、伝熱管には高価な合金鋼を用いねばならない。これに対し、温度が約４００℃程度では炭素鋼でも、仮に空だき等を想定しても、十分に耐えることができ、中圧過熱器１１を安価に構成し得る利点がある。
【００２１】
さらに、排ガス温度が３９０℃の中圧過熱器１１出口蒸気温度に近く、多少の中圧蒸気流量の変動があっても、常に３９０℃の温度水準に保つことができ、プラントの運転上も有利である。
【００２２】
このように本実施の形態によれば、蒸気の合流部において配管等に過大な熱応力が生じるのを防止できるのに加えて、排熱回収ボイラ４を安価に構成することができる。
【００２３】
さらに、好ましい実施の形態を図３を参照して説明する。排熱回収ボイラ４内の主要な機器配置は図１の実施の形態のものと同じである。すなわち、排熱回収ボイラ４は排ガス流動域に高圧二次過熱器５、二次再熱器６、一次再熱器７、高圧一次過熱器８、中圧過熱器１１、高圧蒸発器９、高圧節炭器１２および中圧蒸発器１３を備える。また、中圧過熱器１１から低温再熱蒸気管１７にかけて結ばれる蒸気管２３の経路には中圧過熱器出口蒸気にスプレー水を混合する減温器２４が備えられる。この減温器２４にはスプレー水管２５が接続されており、この経路には調節弁２６が介装されている。また、低温再熱蒸気温度を検出する温度検出器２７の出力と設定温度との偏差に基づいて調節弁２６の開度を調節する温度制御器２８が備えられる。
【００２４】
本実施の形態は上記構成からなり、中圧過熱器１１出口蒸気が減温器２４において所望の温度になるように調節される。プラント運転中、排ガス温度が刻々変化し、このとき、低温再熱蒸気および中圧過熱器１１出口蒸気温度も変動する。低温再熱蒸気温度が、たとえば３９０℃よりも降下したとき、温度検出器２７がこれを検出し、その出力が温度制御器２８において設定温度と比較され、偏差に基づいて調節弁２６の開度が僅かに閉じられる。減温器２４に流れるスプレー水は調節弁２６の閉動作により減少し、減温器２４内を流れる中圧蒸気に少ない量のスプレー水が注入される。
【００２５】
一方、低温再熱蒸気温度が３９０℃を超えて上昇したとき、温度制御器２８から与えられる偏差信号により調節弁２６が開動作する。このとき、減温器２４に流れるスプレー水は増加し、減温器２４内を流れる中圧蒸気により多いスプレー水が注入される。かくして、排ガス温度が変動するようなときも、中圧過熱器１１出口蒸気を低温再熱蒸気と同等の温度水準に保持することができる。
【００２６】
このように本実施の形態によれば、きめ細かな蒸気温度制御により蒸気の合流部において配管等に過大な熱応力が生じるのを確実に防止することができる。
【００２７】
さらに、上述のものと異なる実施の形態を説明する。図４において、排熱回収ボイラ４内の機器配置は従来技術によるものと同一である。低温再熱蒸気管１７の経路には低温再熱蒸気にスプレー水を混合する減温器２９が備えられる。この減温器２９にはスプレー水管３０が接続されており、この経路に調節弁３１が介装されている。また、中圧過熱器１１出口蒸気温度を検出する温度検出器３２の出力に従い調節弁３１の開度を調節する温度制御器３３が備えられる。
【００２８】
本実施の形態は上記構成からなり、低温再熱蒸気が減温器２９において中圧過熱器１１出口蒸気温度に見合うような温度に調節される。たとえば、中圧過熱器１１出口蒸気温度は蒸気タービン２の排気である低温再熱蒸気の温度３９０℃よりも一段と低い約３３０℃である。中圧過熱器１１出口蒸気温度が上限近い温度に上昇する間、温度制御器３３は減温器２９へのスプレー水量を調節する調節弁３１に十分なスプレー水量を確保するようにランプ状に開度を増す信号を出力する。これにより排ガス温度が変動するようなときも、低温再熱蒸気を中圧過熱器１１出口蒸気とほぼ同じ温度水準に下げることができる。
【００２９】
このように本実施の形態においても、蒸気の合流部において配管等に過大な熱応力が発生するのを防止することができる。
【００３０】
【発明の効果】
以上説明したように第１の発明によれば、中圧過熱器を高圧蒸発器より上流側の排ガス流動域に配置するようにしたので、中圧過熱器出口蒸気を蒸気タービンからの低温再熱蒸気とほぼ同じ温度域に保つことができ、蒸気の合流部の配管等に過大な熱応力が生じるのを防ぐことが可能である。
【００３１】
さらに、第２の発明によれば、高圧蒸発器の管群を２分割し、中圧蒸発器を分割した２つの蒸発器の間に配置するようにしたので、中圧過熱器出口蒸気を蒸気タービンからの低温再熱蒸気とほぼ同じ温度域に保つことができ、蒸気の合流部の配管等に過大な熱応力が生じるのを防ぐことが可能である。
【００３２】
また、第３の発明によれば、中圧過熱器出口蒸気にスプレー水を混合する減温器を設け、減温器内に注入されるスプレー水量を低温再熱蒸気温度と設定温度との偏差に基づいて制御するようにしたので、排ガス温度が変動するときも、中圧過熱器出口蒸気を低温再熱蒸気と同等の温度に保つことができ、蒸気の合流部の配管等に過大な熱応力が生じるのを防止することが可能である。
【００３３】
さらに、第４の発明によれば、蒸気タービンからの低温再熱蒸気にスプレー水を混合する減温器を設け、減温器内に注入されるスプレー水量を中圧過熱器出口蒸気温度に基づいて制御するようにしたので、排ガス温度が変動するときも低温再熱蒸気を中圧過熱器出口蒸気と同等の温度に保つことができ、蒸気の合流部の配管等に過大な熱応力が生じるのを防止することが可能である。
【図面の簡単な説明】
【図１】本発明による排熱回収ボイラ装置を示す系統図。
【図２】本発明の他の実施の形態を示す系統図。
【図３】本発明の他の実施の形態を示す系統図。
【図４】本発明の他の実施の形態を示す系統図。
【図５】従来の排熱回収ボイラ装置の一例を示す系統図。
【符号の説明】
２蒸気タービン
４排熱回収ボイラ
６二次再熱器
７一次再熱器
９、２０高圧蒸発器
１１中圧過熱器
１５、１８、２４、２９減温器
２６、３１調節弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust heat recovery boiler apparatus in a combined cycle power plant.
[0002]
[Prior art]
In recent years, many combined cycle power plants have been constructed that can achieve high efficiency in power plants and are excellent in terms of environmental measures. The gas turbine, which is the main prime mover of this combined cycle power plant, is getting larger and the inlet temperature is increasing in order to obtain high efficiency. Along with the increase in size and temperature of the gas turbine, a waste heat recovery boiler is of a double pressure type, a three pressure type, and a plant composed of a reheat cycle comprising a reheat type exhaust heat recovery boiler and a steam turbine. Are also being adopted.
[0003]
An example of the prior art will be described with reference to FIG. The combined cycle power plant drives the generator 3 by the outputs of both the gas turbine device 1 and the steam turbine 2. The exhaust gas from the gas turbine device 1 is used as the heat source of the exhaust heat recovery boiler 4, and the steam generated in the exhaust heat recovery boiler 4 is introduced into the steam turbine 2. The gas turbine apparatus 1 compresses air with a compressor, and mixes and burns it with fuel to obtain a combustion gas of about 1300 ° C., which is expanded to generate power.
[0004]
The combustion gas that has finished work in the gas turbine device 1 is guided to the exhaust heat recovery boiler 4 as exhaust gas. The temperature of the exhaust gas is a high temperature of about 600 ° C., the secondary superheater 5, the secondary reheater 6, the primary reheater 7, the primary superheater 8, the high pressure evaporator 9, the medium pressure superheater 11, and the high pressure economizer. 12, It passes through each tube group of the intermediate pressure evaporator 13, and is discharged into the atmosphere as a gas of about 100 ° C. through a medium pressure economizer and a low pressure economizer (not shown).
[0005]
The exhaust heat recovery boiler 4 includes a high-pressure drum 10 connected to the high-pressure evaporator 9 and an intermediate-pressure drum 14 connected to the intermediate-pressure evaporator 13, and water supplied from the high-pressure drum 10 is supplied to the high-pressure evaporator 9 and the intermediate-pressure drum 14. Is fed to the intermediate pressure evaporator 13 and heated by the exhaust gas described above, and steam for driving the steam turbine 2 is generated. The high-pressure steam generated in the high-pressure evaporator 9 is separated into steam and water by the high-pressure drum 10 and then heated in the primary superheater 8 to form superheated steam. This superheated steam is mixed with spray water in the temperature reducer 15 so that the steam temperature at the outlet of the secondary superheater 5 is adjusted to the set temperature, and passes through the secondary superheater 5 from the main steam pipe 16 to the steam turbine 2. Supplied to the high pressure section.
[0006]
The steam expanded in the steam turbine 2 is guided to the primary reheater 7 through the low temperature reheat steam pipe 17. On the way, this steam is mixed with the outlet steam of the intermediate pressure superheater 11 and flows into the primary reheater 7. The heated reheated steam is mixed with spray water by the temperature reducer 18 and adjusted so that the outlet steam temperature at the secondary reheater 6 becomes the set temperature, and then passes through the secondary reheater 6. The high-temperature reheat steam pipe 19 is supplied to the intermediate pressure portion of the steam turbine 2.
[0007]
[Problems to be solved by the invention]
By the way, in the next generation large capacity combined cycle power plant, the inlet temperature of the gas turbine becomes higher from 1300 ° C. The high-pressure main steam pressure and temperature of the steam turbine using this gas turbine are higher than ever, and the plant efficiency can sufficiently exceed 50%. However, when trying to achieve plant efficiency under the high temperature and high pressure steam conditions, the exhaust temperature of the steam turbine 2, that is, the low temperature reheat steam temperature rises from about 350 ° C. to about 390 ° C., and the intermediate pressure superheater When mixing with 11 outlet steam, the temperature difference of both steam will rise from 20-30 degreeC of the past to 80-90 degreeC. In this case, an excessive thermal stress is generated in the pipe or the like where the both steams merge, and the life of the equipment may be greatly impaired.
[0008]
Accordingly, an object of the present invention is to reduce the temperature difference between the low-temperature reheated steam and the intermediate pressure superheater outlet steam as much as possible to prevent excessive thermal stress from being generated in the piping at the steam confluence. The object is to provide a heat recovery boiler device.
[0009]
[Means for Solving the Problems]
The first invention includes a high-pressure secondary superheater, a secondary reheater, a primary reheater, and a high-pressure primary superheater in order from the upstream side in the flow region of the exhaust gas, and in addition to the heat exchangers. A pressure evaporator, a high-pressure evaporator, and an intermediate-pressure superheater, wherein steam generated in the intermediate-pressure evaporator is heated through the intermediate-pressure superheater and mixed with low-temperature reheated steam led from a high-pressure part of a steam turbine In the exhaust heat recovery boiler apparatus which is heated through the primary reheater and the secondary reheater in order and is supplied to the intermediate pressure portion of the steam turbine, the intermediate pressure superheater is connected to the high pressure evaporation It is arranged in an exhaust gas flow region where an exhaust gas of about 470 ° C. upstream of the steam flows, and the intermediate pressure superheater outlet steam is heated to approximately the same temperature range as the low-temperature reheated steam that becomes about 390 ° C. from the steam turbine. It is characterized by doing so.
[0010]
Furthermore, the second invention includes a high pressure secondary superheater, a secondary reheater, a primary reheater, and a high pressure primary superheater in order from the upstream side in the flow region of the exhaust gas. In addition, a low-temperature reheat steam provided with an intermediate-pressure evaporator, a high-pressure evaporator, and an intermediate-pressure superheater, wherein steam generated in the intermediate-pressure evaporator is heated through the intermediate-pressure superheater and led from a high-pressure portion of a steam turbine In the exhaust heat recovery boiler apparatus which is mixed and heated through the primary reheater and the secondary reheater in order and is supplied to the intermediate pressure portion of the steam turbine, the tube group of the high pressure evaporator And the intermediate pressure superheater is disposed in an exhaust gas flow region where exhaust gas of about 400 ° C. flows between the two evaporators, and the intermediate pressure superheater outlet steam is about 390 ° C. from the steam turbine. In the same temperature range as the low-temperature reheat steam Characterized in that so as to be.
[0011]
A third invention is a temperature reducer that mixes spray water with the outlet steam of the intermediate pressure superheater in the outlet side path of the intermediate pressure superheater, and a control valve that adjusts the amount of spray water injected into the temperature reducer. And a temperature control means for outputting a control signal for adjusting the opening degree of the control valve based on the deviation between the detected low-temperature reheat steam temperature and the set temperature.
[0012]
Furthermore, the fourth invention includes a high-pressure secondary superheater, a secondary reheater, a primary reheater, and a high-pressure primary superheater in order from the upstream side in the exhaust gas flow region, and each of the heat exchangers includes In addition, a low-temperature reheat steam provided with an intermediate-pressure evaporator, a high-pressure evaporator, and an intermediate-pressure superheater, wherein steam generated in the intermediate-pressure evaporator is heated through the intermediate-pressure superheater and led from a high-pressure portion of a steam turbine In the exhaust heat recovery boiler apparatus which is mixed and heated through the primary reheater and the secondary reheater in order and supplied to the intermediate pressure portion of the steam turbine, A temperature reducer that mixes spray water with thermal steam, a control valve that adjusts the amount of spray water injected into the temperature reducer, and an opening degree of the control valve based on the detected steam pressure at the outlet of the intermediate pressure superheater Temperature control hand to output control signal to adjust Characterized in that it comprises and.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, the same reference numerals as those used in FIG. 5 are given to the configurations described by the prior art, and detailed descriptions thereof will be omitted. In FIG. 1, an exhaust heat recovery boiler 4 into which high-temperature exhaust gas flowing out from a gas turbine device 1 is introduced includes a high-pressure secondary superheater 5, a secondary reheater 6, and a primary reheater arranged in tandem in the exhaust gas flow region. 7. A high-pressure primary superheater 8, an intermediate-pressure superheater 11, a high-pressure evaporator 9, a high-pressure economizer 12, and an intermediate-pressure evaporator 13 are provided. That is, the intermediate pressure superheater 11 is disposed in an exhaust gas flow region where an exhaust gas of about 470 ° C. flows upstream from the high pressure evaporator 9, and the steam flowing in the heat transfer pipe of the intermediate pressure superheater 11 is about 470 ° C. The exhaust gas is heated to a temperature of about 390 ° C.
[0014]
The present embodiment is configured as described above, and exhaust gas flows from the gas turbine device 1 into the exhaust heat recovery boiler 4 at the start of the plant, and the inlet temperature rises. Feed water flows from the high-pressure drum 10 to the high-pressure evaporator 9 and is heated by the exhaust gas to generate steam. This steam is superheated to a temperature of about 540 ° C. through the high pressure primary superheater 8 and the high pressure secondary superheater 5. Then, it flows into the steam turbine 2 through the main steam pipe 16.
The steam that has flowed into the steam turbine 2 expands in the steam turbine 2 and the pressure and temperature drop. The steam that has worked in the steam turbine 2 and has reached about 390 ° C. flows to the low-temperature reheat steam pipe 17 and flows again to the primary reheater 7 for heat exchange with the exhaust gas.
[0015]
On the other hand, the feed water flows from the low pressure drum 14 to the intermediate pressure evaporator 13 and is heated by the exhaust gas to generate intermediate pressure steam having a pressure lower than that of the main steam. The intermediate pressure steam is heated to a temperature of about 390 ° C. through an intermediate pressure superheater 11 provided in an exhaust gas flow region in which an exhaust gas of about 470 ° C. upstream of the high pressure evaporator 9 flows.
[0016]
The outlet steam of the intermediate pressure superheater 11 is mixed with the low-temperature reheat steam of about 390 ° C. flowing in the low-temperature reheat steam pipe 17 and flows to the primary reheater 7 together. Thereafter, the low-temperature reheated steam that has flowed to the primary reheater 7 is heated by the exhaust gas, and the temperature of the outlet steam of the secondary reheater 6 is adjusted to 540 ° C. by the temperature reducer 18. Flow into.
[0017]
As described above, according to the present embodiment, the outlet steam of the intermediate pressure superheater 11 can be maintained at substantially the same temperature level as that of the low-temperature reheated steam, and excessively due to a temperature difference in the piping or the like at the joining portion of the steam. It becomes possible to prevent thermal stress from occurring.
[0018]
Furthermore, another embodiment of the present invention will be described with reference to FIG. The high-pressure evaporator 20 according to the present embodiment includes a first evaporator 21 and a second evaporator 22 that are divided into two. The intermediate pressure superheater 11 is disposed between the first evaporator 21 and the second evaporator 22. Except for the points described above, the exhaust heat recovery boiler 4 of FIG. 1 is the same.
[0019]
The present embodiment is configured as described above, and the feed water flows to the intermediate pressure evaporator 13, where it is heated by the exhaust gas, and intermediate pressure steam is generated. This medium pressure steam is heated to a temperature of about 390 ° C. through an intermediate pressure superheater 11 through which exhaust gas of about 400 ° C. flows.
[0020]
The intermediate pressure superheater 11 heated with the exhaust gas of about 400 ° C. can use a heat transfer tube made of carbon steel that is relatively inexpensive due to a decrease in the exhaust gas temperature. That is, in the above embodiment, the intermediate pressure superheater 11 is placed in the exhaust gas at about 470 ° C., and taking into account the emptying operation, an expensive alloy steel must be used for the heat transfer tube. On the other hand, if the temperature is about 400 ° C., even if carbon steel is assumed to be vacant, etc., it can withstand sufficiently, and there is an advantage that the intermediate pressure superheater 11 can be configured at low cost.
[0021]
Furthermore, the exhaust gas temperature is close to the 390 ° C medium-pressure superheater 11 outlet steam temperature, and even if there is some fluctuation in the medium-pressure steam flow rate, it can always be maintained at a temperature level of 390 ° C, which is advantageous for plant operation. It is.
[0022]
As described above, according to the present embodiment, in addition to preventing an excessive thermal stress from being generated in the piping or the like at the joining portion of the steam, the exhaust heat recovery boiler 4 can be configured at a low cost.
[0023]
Furthermore, a preferred embodiment will be described with reference to FIG. The main equipment arrangement in the exhaust heat recovery boiler 4 is the same as that of the embodiment of FIG. That is, the exhaust heat recovery boiler 4 has a high pressure secondary superheater 5, a secondary reheater 6, a primary reheater 7, a high pressure primary superheater 8, an intermediate pressure superheater 11, a high pressure evaporator 9, a high pressure in the exhaust gas flow region. A economizer 12 and an intermediate pressure evaporator 13 are provided. Further, the path of the steam pipe 23 connected from the intermediate pressure superheater 11 to the low temperature reheat steam pipe 17 is provided with a temperature reducer 24 for mixing spray water with the intermediate pressure superheater outlet steam. A spray water pipe 25 is connected to the temperature reducer 24, and a control valve 26 is interposed in this path. In addition, a temperature controller 28 is provided that adjusts the opening of the control valve 26 based on the deviation between the output of the temperature detector 27 that detects the low temperature reheat steam temperature and the set temperature.
[0024]
The present embodiment is configured as described above and is adjusted so that the outlet steam of the intermediate pressure superheater 11 reaches a desired temperature in the temperature reducer 24. During the plant operation, the exhaust gas temperature changes every moment, and at this time, the low-temperature reheat steam and the intermediate pressure superheater 11 outlet steam temperature also fluctuate. When the low-temperature reheat steam temperature falls below, for example, 390 ° C., the temperature detector 27 detects this, and its output is compared with the set temperature in the temperature controller 28, and the opening degree of the control valve 26 based on the deviation. Is slightly closed. The spray water flowing through the temperature reducer 24 is reduced by the closing operation of the control valve 26, and a small amount of spray water is injected into the medium pressure steam flowing through the temperature reducer 24.
[0025]
On the other hand, when the low-temperature reheat steam temperature rises above 390 ° C., the regulating valve 26 opens by the deviation signal given from the temperature controller 28. At this time, the spray water flowing through the temperature reducer 24 increases, and more spray water is injected into the medium pressure steam flowing through the temperature reducer 24. Thus, even when the exhaust gas temperature fluctuates, the intermediate pressure superheater 11 outlet steam can be maintained at the same temperature level as the low-temperature reheat steam.
[0026]
As described above, according to the present embodiment, it is possible to reliably prevent an excessive thermal stress from being generated in the pipe or the like at the steam confluence by fine steam temperature control.
[0027]
Further, an embodiment different from the above will be described. In FIG. 4, the equipment arrangement in the exhaust heat recovery boiler 4 is the same as that in the prior art. The path of the low temperature reheat steam pipe 17 is provided with a temperature reducer 29 for mixing the spray water with the low temperature reheat steam. A spray water pipe 30 is connected to the temperature reducer 29, and a control valve 31 is interposed in this path. Moreover, the temperature controller 33 which adjusts the opening degree of the control valve 31 according to the output of the temperature detector 32 which detects the intermediate pressure superheater 11 outlet steam temperature is provided.
[0028]
The present embodiment is configured as described above, and the temperature of the low-temperature reheat steam is adjusted to match the outlet steam temperature of the intermediate pressure superheater 11 in the temperature reducer 29. For example, the outlet steam temperature of the intermediate pressure superheater 11 is about 330 ° C., which is much lower than the temperature 390 ° C. of the low-temperature reheat steam that is the exhaust of the steam turbine 2. While the steam pressure at the outlet of the intermediate pressure superheater 11 rises to a temperature close to the upper limit, the temperature controller 33 opens in a ramp shape so as to ensure a sufficient amount of spray water for the control valve 31 that adjusts the amount of spray water to the temperature reducer 29. Outputs a signal that increases. As a result, even when the exhaust gas temperature fluctuates, the low-temperature reheated steam can be lowered to substantially the same temperature level as the intermediate pressure superheater 11 outlet steam.
[0029]
As described above, also in the present embodiment, it is possible to prevent excessive thermal stress from being generated in the piping or the like in the steam confluence portion.
[0030]
【The invention's effect】
As described above, according to the first invention, since the intermediate pressure superheater is arranged in the exhaust gas flow region upstream of the high pressure evaporator, the intermediate pressure superheater outlet steam is cooled at low temperature from the steam turbine. It is possible to keep the temperature in substantially the same temperature range as that of the steam, and it is possible to prevent excessive thermal stress from being generated in the piping or the like of the steam confluence.
[0031]
Furthermore, according to the second invention, the tube group of the high-pressure evaporator is divided into two parts, and the intermediate-pressure evaporator is disposed between the two divided evaporators. It is possible to keep the temperature in substantially the same temperature range as the low-temperature reheat steam from the turbine, and it is possible to prevent excessive thermal stress from being generated in the piping or the like of the steam confluence.
[0032]
According to the third aspect of the present invention, a temperature reducer for mixing spray water with the intermediate pressure superheater outlet steam is provided, and the amount of spray water injected into the temperature reducer is determined by the deviation between the low temperature reheat steam temperature and the set temperature. Therefore, even when the exhaust gas temperature fluctuates, the steam at the outlet of the medium pressure superheater can be kept at the same temperature as the low-temperature reheated steam, and excessive heat is generated in the piping at the confluence section of the steam. It is possible to prevent the occurrence of stress.
[0033]
Further, according to the fourth aspect of the present invention, a temperature reducer for mixing the spray water with the low-temperature reheated steam from the steam turbine is provided, and the amount of spray water injected into the temperature reducer is based on the intermediate pressure superheater outlet steam temperature. Therefore, even when the exhaust gas temperature fluctuates, the low-temperature reheated steam can be kept at the same temperature as the outlet steam of the medium-pressure superheater, and excessive thermal stress is generated in the piping at the junction of the steam. It is possible to prevent this.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an exhaust heat recovery boiler apparatus according to the present invention.
FIG. 2 is a system diagram showing another embodiment of the present invention.
FIG. 3 is a system diagram showing another embodiment of the present invention.
FIG. 4 is a system diagram showing another embodiment of the present invention.
FIG. 5 is a system diagram showing an example of a conventional exhaust heat recovery boiler apparatus.
[Explanation of symbols]
2 Steam turbine 4 Waste heat recovery boiler 6 Secondary reheater 7 Primary reheater 9, 20 High pressure evaporator 11 Medium pressure superheater 15, 18, 24, 29 Temperature reducer 26, 31 Control valve

Claims

A high-pressure secondary superheater, secondary reheater, primary reheater, and high-pressure primary superheater are provided in the exhaust gas flow region in order from the upstream side, and in addition to the heat exchangers described above, an intermediate-pressure evaporator and a high-pressure evaporator comprising a vessel and a medium pressure superheater, along with the steam generated in the intermediate-pressure evaporator is heated through the in pressure superheater, the primary reheater is mixed with the cold reheat steam derived from the high pressure section of the steam turbine In the exhaust heat recovery boiler apparatus, which is heated by sequentially passing through the steam generator and the secondary reheater and is supplied to the intermediate pressure portion of the steam turbine,
The intermediate-pressure superheater is disposed in an exhaust gas flow region in which an exhaust gas of about 470 ° C. upstream of the high-pressure evaporator flows , and the intermediate-pressure superheater outlet steam is about 390 ° C. from the steam turbine. The exhaust heat recovery boiler device is characterized in that it is heated to substantially the same temperature range.

A high-pressure secondary superheater, secondary reheater, primary reheater, and high-pressure primary superheater are provided in the exhaust gas flow region in order from the upstream side, and in addition to the heat exchangers described above, an intermediate-pressure evaporator and a high-pressure evaporator comprising a vessel and a medium pressure superheater, along with the steam generated in the intermediate-pressure evaporator is heated through the in pressure superheater, the primary reheater is mixed with the cold reheat steam derived from the high pressure section of the steam turbine In the exhaust heat recovery boiler apparatus, which is heated by sequentially passing through the steam generator and the secondary reheater and is supplied to the intermediate pressure portion of the steam turbine,
The tube group of the high-pressure evaporator is divided into two, and the intermediate-pressure superheater is arranged in an exhaust gas flow region where the exhaust gas of about 400 ° C. flows between the two evaporators. An exhaust heat recovery boiler apparatus that is heated to substantially the same temperature range as a low-temperature reheated steam that is about 390 ° C. from a steam turbine.

A temperature reducer in the outlet side path of the intermediate pressure superheater that mixes the spray water with the intermediate pressure superheater outlet steam, and a control valve that adjusts the amount of spray water injected into the temperature reducer; The exhaust heat recovery boiler apparatus according to claim 1, further comprising temperature control means for outputting a control signal for adjusting the opening of the control valve based on a deviation between the low temperature reheat steam temperature and the set temperature. .

A high-pressure secondary superheater, secondary reheater, primary reheater, and high-pressure primary superheater are provided in the exhaust gas flow region in order from the upstream side, and in addition to the heat exchangers described above, an intermediate-pressure evaporator and a high-pressure evaporator comprising a vessel and a medium pressure superheater, along with the steam generated in the intermediate-pressure evaporator is heated through the in pressure superheater, the primary reheater is mixed with the cold reheat steam derived from the high pressure section of the steam turbine In the exhaust heat recovery boiler apparatus, which is heated by sequentially passing through the steam generator and the secondary reheater and is supplied to the intermediate pressure portion of the steam turbine,
A temperature reducer for mixing spray water with the low-temperature reheated steam from the steam turbine; a control valve for adjusting the amount of spray water injected into the temperature reducer; and the detected temperature of the intermediate pressure superheater outlet steam And a temperature control means for outputting a control signal for adjusting the opening of the control valve.