JP7111525B2 - Once-through heat recovery boiler and control system for once-through heat recovery boiler - Google Patents

Once-through heat recovery boiler and control system for once-through heat recovery boiler Download PDF

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JP7111525B2
JP7111525B2 JP2018120055A JP2018120055A JP7111525B2 JP 7111525 B2 JP7111525 B2 JP 7111525B2 JP 2018120055 A JP2018120055 A JP 2018120055A JP 2018120055 A JP2018120055 A JP 2018120055A JP 7111525 B2 JP7111525 B2 JP 7111525B2
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和弘 武永
康裕 竹井
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Mitsubishi Heavy Industries Ltd
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    • 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
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Description

本発明は、ガスタービンと排熱回収ボイラと蒸気タービンとを備えるコンバインドサイクル発電設備の排熱回収ボイラに関し、特に、貫流式排熱回収ボイラに関する。 TECHNICAL FIELD The present invention relates to a heat recovery boiler for a combined cycle power generation facility including a gas turbine, a heat recovery boiler and a steam turbine, and more particularly to a once-through heat recovery boiler.

ガスタービンの排ガスから熱交換によって蒸気を発生させ、その蒸気を用いて蒸気タービンを駆動して発電する、いわゆるコンバインドサイクル発電設備がある。図７（ａ）は、一般的なコンバインドサイクル発電設備１００のプラント構成を示すブロック図である。 BACKGROUND ART There is a so-called combined cycle power generation facility in which steam is generated by heat exchange from exhaust gas of a gas turbine, and the steam is used to drive a steam turbine to generate power. FIG. 7(a) is a block diagram showing a plant configuration of a general combined cycle power generation facility 100. FIG.

図７（ａ）に示すように、コンバインドサイクル発電設備１００では、発電機４と、蒸気タービン３と、ガスタービン１とが連続して設けられ、ガスタービン１で天然ガス等を燃焼させて発電機４にて発電を行う。 As shown in FIG. 7A, in the combined cycle power generation facility 100, a generator 4, a steam turbine 3, and a gas turbine 1 are provided in series, and the gas turbine 1 burns natural gas or the like to generate power. The generator 4 generates electricity.

ガスタービン１から排出される高温の排ガスは、排熱回収ボイラ２に送られる。排熱回収ボイラ２では、排ガスからの熱回収により、給水を蒸気に変換する。変換された蒸気は、蒸気タービン３に送られて発電機４において発電に用いられる。蒸気タービン３にて仕事をした蒸気は、復水器５にて復水され、復水された水は再び排熱回収ボイラ２へと送られる。 High-temperature exhaust gas discharged from the gas turbine 1 is sent to the heat recovery steam generator 2 . The exhaust heat recovery boiler 2 converts the feed water into steam by recovering heat from the exhaust gas. The converted steam is sent to the steam turbine 3 and used in the power generator 4 for power generation. The steam that has worked in the steam turbine 3 is condensed in the condenser 5 and the condensed water is sent to the heat recovery boiler 2 again.

大型のコンバインドサイクル発電設備１００では、例えば、特許文献１に開示されているように、この排熱回収ボイラ２の蒸気系統を高圧系、中圧系および低圧系の三重圧方式で構成して排熱回収の効率を向上させている。このような排熱回収ボイラ２は、高圧系には、汽水分離器を用いる貫流システムを採用し、中、低圧系にはドラムを用いる自然循環システムを採用し、貫流式排熱回収ボイラ２と呼ばれる。 In the large-sized combined cycle power generation facility 100, for example, as disclosed in Patent Document 1, the steam system of the heat recovery boiler 2 is configured in a triple pressure system of a high-pressure system, an intermediate-pressure system and a low-pressure system to exhaust the exhaust gas. It improves the efficiency of heat recovery. Such a waste heat recovery boiler 2 adopts a once-through system using a steam separator for the high pressure system, and a natural circulation system using a drum for the middle and low pressure systems. be called.

従来の貫流式排熱回収ボイラ２は、図７（ｂ）に示すように、高圧系蒸気系統である高圧系４１と、中圧系蒸気系統である中圧系４２と、低圧系蒸気系統である低圧系４３と、を備える。 As shown in FIG. 7B, the conventional once-through heat recovery boiler 2 includes a high pressure system 41 that is a high pressure steam system, an intermediate pressure system 42 that is an intermediate pressure steam system, and a low pressure steam system. a low pressure system 43;

各蒸気系統は、それぞれ、ガスタービン１からの排ガスが流通する排ガス流路の上流側から下流側に順に、過熱器と蒸発器と節炭器と、を備える。具体的には、低圧系４３は、低圧過熱器１２と、低圧蒸発器１１と、低圧ドラム１０と、低圧節炭器９と、を備える。また、中圧系４２は、中圧過熱器１８と、中圧蒸発器１７と、中圧ドラム１６と、中圧節炭器１５と、を備える。高圧系４１は、高圧過熱器２３と、高圧蒸発器２１と、高圧汽水分離器２２と、高圧節炭器１９と、を備える。 Each steam system includes a superheater, an evaporator, and an economizer in order from the upstream side to the downstream side of an exhaust gas passage through which exhaust gas from the gas turbine 1 flows. Specifically, the low pressure system 43 includes a low pressure superheater 12 , a low pressure evaporator 11 , a low pressure drum 10 and a low pressure economizer 9 . The intermediate pressure system 42 also includes an intermediate pressure superheater 18 , an intermediate pressure evaporator 17 , an intermediate pressure drum 16 , and an intermediate pressure economizer 15 . The high pressure system 41 includes a high pressure superheater 23 , a high pressure evaporator 21 , a high pressure steam separator 22 and a high pressure economizer 19 .

高圧汽水分離器２２の飽和水排出口には、復水器５へとつながる起動ブローライン２６が設置される。起動ブローライン２６には、起動ブロー弁２７が設けられる。また、高圧汽水分離器２２の飽和水排出口には、ブロータンク２８へつながるブローライン３８も設置される。さらに、高圧汽水分離器２２の飽和水排出口には、高圧汽水分離器２２にて分離された飽和水を高圧蒸発器２１に戻す蒸発器循環ライン２４が設けられる。 A start blow line 26 leading to the condenser 5 is installed at the saturated water outlet of the high-pressure steam separator 22 . An activation blow valve 27 is provided in the activation blow line 26 . A blow line 38 leading to a blow tank 28 is also installed at the saturated water outlet of the high-pressure steam separator 22 . Furthermore, the saturated water outlet of the high pressure steam separator 22 is provided with an evaporator circulation line 24 for returning the saturated water separated by the high pressure steam separator 22 to the high pressure evaporator 21 .

ガスタービン１からの排ガスは、最初の蒸気系統である高圧系４１の高圧過熱器２３から、最後流部に設置された低圧系４３の低圧節炭器９まで送られ、その間、各蒸気系統で排ガスの保有熱の熱回収が行われる。 Exhaust gas from the gas turbine 1 is sent from the high-pressure superheater 23 of the high-pressure system 41, which is the first steam system, to the low-pressure economizer 9 of the low-pressure system 43 installed at the rearmost stream. Heat recovery of the residual heat of the exhaust gas is performed.

復水器５にて復水された水は、復水ポンプ６、復水脱塩装置７、低圧給水ポンプ８を経て貫流式排熱回収ボイラ２の給水入口へと送られる。貫流式排熱回収ボイラ２に供給された給水は、低圧系４３、中圧系４２、高圧系４１の順に流れる間に排ガスとの熱交換により蒸気となる。 The water condensed in the condenser 5 is sent to the feed water inlet of the once-through heat recovery steam generator 2 via the condensate pump 6 , the condensate demineralizer 7 , and the low-pressure feed water pump 8 . The feed water supplied to the once-through heat recovery boiler 2 becomes steam through heat exchange with the exhaust gas while flowing through the low pressure system 43, the intermediate pressure system 42, and the high pressure system 41 in this order.

特表２０１７－５３４８２８号公報Japanese Patent Publication No. 2017-534828

上述の貫流式排熱回収ボイラ２では、通常運転時は、高圧節炭器１９でさらに加熱された高圧給水は、全て高圧蒸発器２１で蒸気へと変換され、高圧汽水分離器２２を経て高圧過熱器２３へ供給される。このような運転を、貫流運転と呼ぶ。 In the above-described once-through heat recovery boiler 2, during normal operation, all of the high-pressure feed water further heated by the high-pressure economizer 19 is converted into steam by the high-pressure evaporator 21, and passed through the high-pressure steam separator 22 to produce high-pressure steam. It is supplied to the superheater 23 . Such operation is called once-through operation.

一方、ガスタービン１からの入熱量が少なく変動も大きい起動時等は、高圧蒸発器２１の出口の流体は飽和二相流となる。このような状態では、貫流式排熱回収ボイラ２では、高圧汽水分離器２２で汽水分離した飽和蒸気のみ高圧過熱器２３へと送り、飽和水は、高圧汽水分離器２２の下部より高圧蒸発器２１の入口へと戻す蒸発器循環運転が行われる。 On the other hand, the fluid at the outlet of the high-pressure evaporator 21 becomes a saturated two-phase flow when the amount of heat input from the gas turbine 1 is small and fluctuates greatly. In such a state, in the once-through heat recovery boiler 2, only the saturated steam separated from steam by the high-pressure steam separator 22 is sent to the high-pressure superheater 23, and the saturated water is sent from the lower part of the high-pressure steam separator 22 to the high-pressure evaporator. An evaporator circulation operation is performed to return to the inlet of 21 .

この蒸発器循環運転中、高圧蒸発器２１を含む蒸発器循環系統内の比容積差により十分な循環力が得られ、豊富な蒸発器管内流量が確保できる場合は、高圧汽水分離器２２で汽水分離された飽和水は、圧力バランスのみで、高圧蒸発器２１の入口側へ自然循環する。従って、高圧汽水分離器２２の下部から高圧蒸発器２１へ飽和水は継続的に供給され、ガスタービン１の排ガスの入熱量変動等により高圧蒸発器２１へ給水が供給されない運転状態になったとしても、高圧蒸発器２１が異常加熱されることはない。 During this evaporator circulation operation, when sufficient circulation power is obtained due to the specific volume difference in the evaporator circulation system including the high pressure evaporator 21 and a large flow rate in the evaporator pipe can be secured, the high pressure steam separator 22 The separated saturated water naturally circulates to the inlet side of the high-pressure evaporator 21 only by pressure balance. Therefore, even if the saturated water is continuously supplied to the high-pressure evaporator 21 from the lower part of the high-pressure steam separator 22 and the feed water is not supplied to the high-pressure evaporator 21 due to fluctuations in the heat input of the exhaust gas of the gas turbine 1, etc. Also, the high-pressure evaporator 21 is not abnormally heated.

しかしながら、高圧蒸発器２１の圧力損失が大きい場合には自然循環力が得られず、飽和水が蒸発器入口に循環しないため、蒸発器管内流量が著しく低下し、一時的に停滞することもある。このような場合は、蒸発器循環ライン２４に設置された蒸発器循環ポンプ２５を用いて強制循環運転を行って、高圧蒸発器２１の異常加熱を防止する必要がある。この蒸発器循環ポンプ２５は、高圧系４１内に配置されるため、高コストであり、また、蒸発器循環ポンプ２５を駆動させるための補機動力が必要となる。そのため、貫流式排熱回収ボイラ２の低コスト化の実現のためには、蒸発器循環ポンプ２５および蒸発器循環ライン２４をなくすことは非常に有効である。 However, when the pressure loss of the high-pressure evaporator 21 is large, the natural circulation force cannot be obtained, and the saturated water does not circulate to the evaporator inlet. . In such a case, it is necessary to prevent abnormal heating of the high-pressure evaporator 21 by performing forced circulation operation using the evaporator circulation pump 25 installed in the evaporator circulation line 24 . Since the evaporator circulation pump 25 is arranged in the high-pressure system 41 , it is expensive and requires auxiliary power for driving the evaporator circulation pump 25 . Therefore, it is very effective to eliminate the evaporator circulation pump 25 and the evaporator circulation line 24 in order to reduce the cost of the once-through heat recovery boiler 2 .

蒸発器循環ライン２４を設けずに、高圧蒸発器２１の異常加熱を防止するためには、蒸発量が低下した際にも、高圧蒸発器２１への給水の供給を継続する手法を適用すれば良い。しかし、この手法では、過剰な給水に伴って高圧汽水分離器２２の水位が上昇した際は、高圧汽水分離器２２の飽和水を、起動ブローライン２６を経由して復水器５に排出するか、あるいは、ブロータンク２８へ排出することが必要となる。そのため、高圧蒸発器２１までの各部で回収した熱を損失し、貫流式排熱回収ボイラ２の起動時間が増加するといった課題や、ブロータンク２８に排水するため、補給水量が増加するといった課題が生じる。 In order to prevent abnormal heating of the high-pressure evaporator 21 without providing the evaporator circulation line 24, a method of continuing to supply water to the high-pressure evaporator 21 even when the amount of evaporation decreases is applied. good. However, in this method, when the water level of the high-pressure steam separator 22 rises due to excessive water supply, the saturated water of the high-pressure steam separator 22 is discharged to the condenser 5 via the start blow line 26. Alternatively, discharge to blow tank 28 is required. Therefore, the heat recovered in each part up to the high-pressure evaporator 21 is lost, and the start-up time of the once-through heat recovery boiler 2 is increased. occur.

本発明は、上記事情に鑑みてなされたもので、貫流式排熱回収ボイラにおいて、コストの上昇とエネルギの損失とを抑えつつ、起動時における安定した蒸発器循環運転を実現することを目的とする。 SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to realize stable evaporator circulation operation at startup while suppressing cost increases and energy loss in once-through heat recovery steam generators. do.

本発明は、それぞれ、ガスタービンからの排ガスが流通する排ガス流路の上流側から下流側に順に過熱器、蒸発器および節炭器を有する高圧系、中圧系および低圧系を備え、前記中圧系および前記低圧系は、それぞれ蒸気ドラムを備え、前記高圧系は、汽水分離器を備える貫流式排熱回収ボイラであって、前記汽水分離器の飽和水を、前記中圧系および前記低圧系のいずれかに戻す蒸発器循環ラインを備えることを特徴とする。 The present invention comprises a high-pressure system, an intermediate-pressure system and a low-pressure system each having a superheater, an evaporator and an economizer in order from the upstream side to the downstream side of an exhaust gas flow path through which exhaust gas from a gas turbine flows. The high-pressure system and the low-pressure system each comprise a steam drum, and the high-pressure system is a once-through heat recovery boiler comprising a steam separator, wherein the saturated water of the steam separator is transferred to the intermediate-pressure system and the low-pressure system. It is characterized by having an evaporator circulation line returning to either of the systems.

また、本発明は、それぞれ、ガスタービンからの排ガスが流通する排ガス流路の上流側から下流側に順に過熱器、蒸発器および節炭器を有する高圧系、中圧系および低圧系を備え、前記中圧系および前記低圧系は、それぞれ蒸気ドラムを備え、前記高圧系は、汽水分離器を備える貫流式排熱回収ボイラの制御システムであって、前記貫流式排熱回収ボイラは、前記汽水分離器の飽和水を、前記中圧系および前記低圧系のいずれかに戻す蒸発器循環ラインと、前記高圧系の蒸発器の管内流量を計測する高圧蒸発器入口給水流量計と、前記蒸発器循環ライン上に設けられる循環流量調節弁と、を備え、起動時に、前記高圧蒸発器入口給水流量計で計測された前記管内流量が予め定めた流量規定値となるよう前記循環流量調節弁の開度を制御することを特徴とする。 Further, the present invention comprises a high-pressure system, an intermediate-pressure system and a low-pressure system each having a superheater, an evaporator and an economizer in order from the upstream side to the downstream side of an exhaust gas flow path through which the exhaust gas from the gas turbine flows, The intermediate-pressure system and the low-pressure system each include a steam drum, and the high-pressure system is a control system for a once-through heat recovery boiler having a steam separator, wherein the once-through heat recovery boiler is equipped with a steam drum. An evaporator circulation line that returns the saturated water of the separator to either the intermediate pressure system or the low pressure system, a high pressure evaporator inlet feed water flow meter that measures the flow rate in the evaporator pipe of the high pressure system, and the evaporator. and a circulation flow rate control valve provided on the circulation line, wherein the circulation flow rate control valve is opened so that the pipe flow rate measured by the high-pressure evaporator inlet feed water flow meter becomes a predetermined flow rate specified value at the time of startup. It is characterized by controlling the degree.

本発明によれば、貫流式排熱回収ボイラにおいて、コストの上昇とエネルギの損失とを抑えつつ、起動時における安定した蒸発器循環運転状態を実現できる。上記した以外の課題、構成および効果は、以下の実施形態の説明により明らかにされる。 According to the present invention, in a once-through heat recovery boiler, it is possible to realize a stable evaporator circulation operation state at the time of start-up while suppressing an increase in cost and loss of energy. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

（ａ）は、第一の実施形態の貫流式排熱回収ボイラの系統構成を、（ｂ）は、第一の実施形態の変形例１の貫流式排熱回収ボイラの系統構成を、それぞれ示す図である。(a) shows the system configuration of the once-through heat recovery boiler of the first embodiment, and (b) shows the system configuration of the once-through heat recovery boiler of Modification 1 of the first embodiment. It is a diagram. 第一の実施形態のコントローラの機能ブロック図である。3 is a functional block diagram of the controller of the first embodiment; FIG. （ａ）は、第一の実施形態と従来との調節弁開度を比較して示す図であり、（ｂ）は、本発明の第一および第三の実施形態と従来との起動時の低圧節炭器給水入口温度特性を比較して示す図である。(a) is a diagram showing a comparison of the opening degrees of the control valve between the first embodiment and the conventional art; It is a figure which compares and shows a low-pressure economizer feed water inlet temperature characteristic. 第一の実施形態の変形例２の貫流式排熱回収ボイラの系統構成を示す図である。FIG. 3 is a diagram showing a system configuration of a once-through heat recovery steam generator of Modification 2 of the first embodiment; 第二の実施形態の貫流式排熱回収ボイラの系統構成を示す図である。FIG. 2 is a diagram showing a system configuration of a once-through heat recovery steam generator of a second embodiment; （ａ）は、第三の実施形態の貫流式排熱回収ボイラの系統構成を、（ｂ）は、第三の実施形態の変形例の貫流式排熱回収ボイラの系統構成を、それぞれ示す図である。(a) shows the system configuration of the once-through heat recovery steam generator of the third embodiment, and (b) shows the system configuration of the once-through heat recovery boiler of the modified example of the third embodiment. is. （ａ）は、コンバインドサイクル発電設備のプラント構成を、（ｂ）は、従来の貫流式排熱回収ボイラの系統構成を、それぞれ示す図である。(a) is a diagram showing a plant configuration of a combined cycle power generation facility, and (b) is a diagram showing a system configuration of a conventional once-through heat recovery boiler.

本発明の実施形態に係る貫流式排熱回収ボイラについて説明する。本発明の実施形態の貫流式排熱回収ボイラは、図７（ａ）に示すコンバインドサイクル発電設備１００で用いられる。 A once-through heat recovery boiler according to an embodiment of the present invention will be described. A once-through heat recovery boiler according to an embodiment of the present invention is used in a combined cycle power generation facility 100 shown in FIG. 7(a).

本発明の実施形態に係る貫流式排熱回収ボイラは、図７（ｂ）に示す従来の貫流式排熱回収ボイラ２における蒸発器循環ポンプ２５および蒸発器循環ライン２４を設けていない点に構成上の特徴がある。 The once-through heat recovery boiler according to the embodiment of the present invention is configured in that the evaporator circulation pump 25 and the evaporator circulation line 24 in the conventional once-through heat recovery boiler 2 shown in FIG. 7(b) are not provided. It has the above features.

具体的には、本発明の実施形態に係る貫流式排熱回収ボイラは、蒸発器循環ポンプ２５および蒸発器循環ライン２４の代わりに、高圧汽水分離器２２の飽和水を、中圧系４２および低圧系４３のいずれかに戻す蒸発器循環ライン２４ａ，２４ｂ，２４ｃを備えている。そして、起動時等における蒸発器循環運転の際には、蒸発器循環ライン２４ａ，２４ｂ，２４ｃを流れる高圧汽水分離器２２からの飽和水の戻り流量を調整することで、高圧蒸発器２１への給水の供給を継続し、高圧蒸発器２１の異常加熱を防止している。以下、本発明の各実施形態について詳しく説明するが、各実施形態において、図７（ｂ）に示す従来の貫流式排熱回収ボイラ２と同一の構成については同一の符号を付して詳しい説明を省略する。 Specifically, in the once-through heat recovery boiler according to the embodiment of the present invention, instead of the evaporator circulation pump 25 and the evaporator circulation line 24, the saturated water of the high pressure steam separator 22 is used as the intermediate pressure system 42 and Evaporator circulation lines 24a, 24b, 24c returning to any of the low pressure systems 43 are provided. During the evaporator circulation operation at the time of start-up or the like, by adjusting the return flow rate of saturated water from the high pressure steam separator 22 flowing through the evaporator circulation lines 24a, 24b, 24c, the flow rate of saturated water to the high pressure evaporator 21 is adjusted. The supply of water is continued to prevent abnormal heating of the high-pressure evaporator 21 . Hereinafter, each embodiment of the present invention will be described in detail. In each embodiment, the same components as those of the conventional once-through heat recovery boiler 2 shown in FIG. omitted.

＜＜第一の実施形態＞＞
本発明の第一の実施形態を説明する。図１（ａ）に、本実施形態の貫流式排熱回収ボイラ２ａの一例を示す。 <<First Embodiment>>
A first embodiment of the present invention will be described. FIG. 1(a) shows an example of a once-through heat recovery boiler 2a of the present embodiment.

本実施形態の貫流式排熱回収ボイラ２ａにおいて、蒸発器循環ライン２４ａは、高圧汽水分離器２２の飽和水排出口に接続された下降管から分岐し、低圧系４３の低圧節炭器９の入口配管に接続される。また、蒸発器循環ライン２４ａには、蒸発器循環流量調節弁２９が設けられる。 In the once-through heat recovery boiler 2a of the present embodiment, the evaporator circulation line 24a branches from a descending pipe connected to the saturated water outlet of the high-pressure steam separator 22, and the low-pressure economizer 9 of the low-pressure system 43 Connected to inlet piping. An evaporator circulation flow control valve 29 is provided in the evaporator circulation line 24a.

低圧節炭器９の入口には、復水器５からの給水を低圧節炭器９に供給する復水ライン３７が接続される。復水ライン３７には、復水ポンプ６と、復水脱塩装置７と、低圧給水ポンプ８と、が設けられる。また復水ライン３７の、低圧節炭器９の入口近傍には、低圧節炭器９に供給される給水の温度を計測する低圧節炭器入口給水温度計３４が設けられる。 An inlet of the low-pressure economizer 9 is connected to a condensate line 37 that supplies water from the condenser 5 to the low-pressure economizer 9 . The condensate line 37 is provided with a condensate pump 6 , a condensate demineralizer 7 , and a low-pressure feed water pump 8 . A low-pressure economizer inlet feedwater thermometer 34 for measuring the temperature of the feed water supplied to the low-pressure economizer 9 is provided in the condensate line 37 near the inlet of the low-pressure economizer 9 .

低圧節炭器９の出口には、低圧節炭器９で加熱された給水を中圧節炭器１５および高圧節炭器１９へと供給する高中圧給水ライン３５が設けられる。この高中圧給水ライン３５には、高中圧給水ポンプ１３と、高圧給水調節弁２０とが設けられる。 At the outlet of the low-pressure economizer 9, a high-intermediate-pressure water supply line 35 for supplying the water heated by the low-pressure economizer 9 to the medium-pressure economizer 15 and the high-pressure economizer 19 is provided. The high and intermediate pressure water supply line 35 is provided with a high and intermediate pressure water supply pump 13 and a high pressure water supply control valve 20 .

低圧節炭器９の出口には、さらに、低圧節炭器９で加熱された給水を、低圧節炭器９の入口に再循環させる節炭器再循環ライン１４が設けられる。節炭器再循環ライン１４には、節炭器再循環ポンプ３６と、低圧節炭器入口温度調節弁３２とが設けられる。 The outlet of the low pressure economizer 9 is further provided with an economizer recirculation line 14 for recirculating the feed water heated in the low pressure economizer 9 to the inlet of the low pressure economizer 9 . The economizer recirculation line 14 is provided with an economizer recirculation pump 36 and a low-pressure economizer inlet temperature control valve 32 .

また、本実施形態の貫流式排熱回収ボイラ２ａは、コントローラ２００を備え、低圧節炭器９の給水入口温度、高圧蒸発器２１の管内流量、各蒸気系統の運転圧力、高圧汽水分離器２２の水位等をモニタし、モニタ結果に応じて各調節弁の開閉を制御する。 In addition, the once-through heat recovery boiler 2a of the present embodiment is provided with a controller 200, the feed water inlet temperature of the low-pressure economizer 9, the flow rate in the high-pressure evaporator 21, the operating pressure of each steam system, the high-pressure steam separator 22 monitor the water level, etc., and control the opening and closing of each control valve according to the monitoring results.

次に、本実施形態のコントローラ２００による制御を説明する。図２は、本実施形態のコントローラ２００の機能ブロック図である。 Next, control by the controller 200 of this embodiment will be described. FIG. 2 is a functional block diagram of the controller 200 of this embodiment.

本実施形態のコントローラ２００は、高圧蒸発器２１の入口に設けられた高圧蒸発器入口給水流量計３３の出力をモニタし、予め定めた規定値（流量規定値）となるよう、蒸発器循環流量調節弁２９に対し、指令信号を出力する。これを実現するため、本実施形態のコントローラ２００は、流量検出部２１１と、循環流量調節弁開閉制御部２１２と、を備える。 The controller 200 of the present embodiment monitors the output of a high-pressure evaporator inlet feed water flow meter 33 provided at the inlet of the high-pressure evaporator 21, and adjusts the evaporator circulation flow rate to a predetermined specified value (flow rate specified value). A command signal is output to the control valve 29 . In order to realize this, the controller 200 of the present embodiment includes a flow rate detection section 211 and a circulation flow rate adjustment valve opening/closing control section 212 .

また、本実施形態のコントローラ２００は、低圧節炭器入口温度調節弁３２の開閉も制御する。コントローラ２００は、蒸発器循環流量調節弁２９が開いている間は、低圧節炭器入口温度調節弁３２を閉じる。一方、蒸発器循環運転が終了し、蒸発器循環流量調節弁２９が閉じられると、コントローラ２００は、低圧節炭器９の給水入口温度が、規定値（水温規定値）となるよう、低圧節炭器入口温度調節弁３２の開度を調整する。これを実現するため、本実施形態のコントローラ２００は、水温検出部２１３と、入口温度調節弁開閉制御部２１４と、を備える。 The controller 200 of this embodiment also controls opening and closing of the low-pressure economizer inlet temperature control valve 32 . The controller 200 closes the low pressure economizer inlet temperature control valve 32 while the evaporator circulation flow control valve 29 is open. On the other hand, when the evaporator circulation operation is completed and the evaporator circulation flow control valve 29 is closed, the controller 200 controls the low pressure economizer so that the feed water inlet temperature of the low pressure economizer 9 becomes a specified value (water temperature specified value). The opening degree of the charcoal inlet temperature control valve 32 is adjusted. In order to realize this, the controller 200 of this embodiment includes a water temperature detection section 213 and an inlet temperature control valve opening/closing control section 214 .

流量検出部２１１は、高圧蒸発器入口給水流量計３３をモニタし、モニタ結果、すなわち、検出流量を、循環流量調節弁開閉制御部２１２に出力する。モニタは、例えば、ガスタービン１が点火された後、所定の時間間隔で行う。 The flow rate detection unit 211 monitors the high-pressure evaporator inlet feed water flow meter 33 and outputs the monitoring result, that is, the detected flow rate, to the circulation flow control valve opening/closing control unit 212 . Monitoring is performed, for example, at predetermined time intervals after the gas turbine 1 is ignited.

循環流量調節弁開閉制御部２１２は、高圧蒸発器２１の管内流量が、流量規定値となるよう、蒸発器循環流量調節弁２９の開度を調整する。本実施形態では、循環流量調節弁開閉制御部２１２は、流量検出部２１１から受信した高圧蒸発器２１の管内流量に応じて、蒸発器循環流量調節弁２９に開度を指示する指令信号（開度信号）を出力する。循環流量調節弁開閉制御部２１２は、流量検出部２１１から検出流量を受信する毎に開度を決定し、開度信号を出力する。なお、開度を０とする開度信号、すなわち、閉指令は、蒸発器循環流量調節弁２９だけでなく、入口温度調節弁開閉制御部２１４にも出力する。 The circulation flow control valve opening/closing control unit 212 adjusts the opening degree of the evaporator circulation flow control valve 29 so that the flow rate in the pipe of the high-pressure evaporator 21 becomes a specified flow rate value. In this embodiment, the circulating flow control valve opening/closing control unit 212 outputs a command signal (open) to the evaporator circulating flow control valve 29 according to the flow rate in the pipe of the high-pressure evaporator 21 received from the flow detection unit 211 . degree signal). The circulation flow control valve opening/closing control unit 212 determines the degree of opening each time it receives the detected flow rate from the flow rate detection unit 211, and outputs an opening degree signal. An opening degree signal that sets the opening degree to 0, that is, a closing command is output not only to the evaporator circulation flow rate control valve 29 but also to the inlet temperature control valve opening/closing control section 214 .

循環流量調節弁開閉制御部２１２は、例えば、流量規定値を目標値、管内流量を制御量、蒸発器循環流量調節弁２９の開度を操作量とするＰＩＤ（Ｐｒｏｐｏｒｔｉｏｎａｌ－Ｉｎｔｅｇｒａｌ－Ｄｉｆｆｅｒｅｎｔｉａｌ）制御を行う比例積分調節器等で実現される。 The circulation flow control valve opening/closing control unit 212 performs PID (Proportional-Integral-Differential) control using, for example, the specified flow rate as the target value, the pipe flow rate as the control amount, and the opening of the evaporator circulation flow control valve 29 as the manipulated variable. It is realized by a proportional-integral controller or the like.

蒸発器循環流量調節弁２９の開度の時間的な変化の一例を図３（ａ）上段のグラフ３０１に示す。ここでは、ガスタービン（ＧＴ）点火直前から、蒸発器循環運転終了直後までの変化の様子を示す。 An example of temporal changes in the degree of opening of the evaporator circulation flow control valve 29 is shown in graph 301 in the upper part of FIG. 3(a). Here, the state of change from immediately before ignition of the gas turbine (GT) to immediately after the end of the evaporator circulation operation is shown.

水温検出部２１３は、低圧節炭器入口給水温度計３４をモニタし、モニタ結果、すなわち、検出水温を、入口温度調節弁開閉制御部２１４に出力する。モニタは、例えば、ガスタービン１が点火された後、所定の時間間隔で行う。 The water temperature detection unit 213 monitors the low-pressure economizer inlet feed water thermometer 34 and outputs the monitoring result, that is, the detected water temperature, to the inlet temperature control valve opening/closing control unit 214 . Monitoring is performed, for example, at predetermined time intervals after the gas turbine 1 is ignited.

入口温度調節弁開閉制御部２１４は、蒸発器循環流量調節弁２９が閉じられている間、低圧節炭器９の給水入口温度が、水温規定値となるよう、低圧節炭器入口温度調節弁３２の開度を調整する。 The inlet temperature control valve opening/closing control unit 214 controls the temperature at the inlet of the low-pressure economizer so that the feed water inlet temperature of the low-pressure economizer 9 reaches the water temperature specified value while the evaporator circulation flow rate control valve 29 is closed. Adjust the opening of 32.

本実施形態では、入口温度調節弁開閉制御部２１４は、循環流量調節弁開閉制御部２１２から閉指令を受信している間、水温検出部２１３から受信した水温に応じて、低圧節炭器入口温度調節弁３２に開度信号を出力する。入口温度調節弁開閉制御部２１４も、循環流量調節弁開閉制御部２１２同様、例えば、比例積分調節器等で実現される。 In the present embodiment, the inlet temperature control valve opening/closing control unit 214 receives the closing command from the circulation flow rate control valve opening/closing control unit 212, according to the water temperature received from the water temperature detection unit 213, the low-pressure economizer inlet An opening degree signal is output to the temperature control valve 32 . The inlet temperature control valve opening/closing control unit 214 is also realized by, for example, a proportional-integral controller or the like, like the circulation flow rate control valve opening/closing control unit 212 .

低圧節炭器入口温度調節弁３２の開度の時間的な変化の一例を図３（ａ）下段のグラフ３０２に示す。ここでは、ガスタービン（ＧＴ）１点火直前から、循環運転終了直後までの変化の様子を示す。 An example of a temporal change in the degree of opening of the low-pressure economizer inlet temperature control valve 32 is shown in the lower graph 302 of FIG. 3(a). Here, the state of change from immediately before the ignition of the gas turbine (GT) 1 to immediately after the end of the circulation operation is shown.

図３（ａ）に示すように、本実施形態では、蒸発器循環運転が終了し、蒸発器循環流量調節弁２９が閉じてくると（３０３）、低圧節炭器入口温度調節弁３２が開き、低圧節炭器９の給水入口温度の制御が開始される。 As shown in FIG. 3(a), in this embodiment, when the evaporator circulation operation ends and the evaporator circulation flow control valve 29 closes (303), the low-pressure economizer inlet temperature control valve 32 opens. , the control of the feed water inlet temperature of the low-pressure economizer 9 is started.

例えば、上述の従来の貫流式排熱回収ボイラ２では、本実施形態のように、低圧節炭器９の入口に接続される蒸発器循環ライン２４ａと、蒸発器循環流量調節弁２９と、を備えない。従って、ガスタービン１の点火後から、低圧節炭器入口温度調節弁３２を開くよう制御される。 For example, in the above-described conventional once-through heat recovery boiler 2, the evaporator circulation line 24a connected to the inlet of the low-pressure economizer 9 and the evaporator circulation flow control valve 29 are provided as in the present embodiment. Not prepared. Therefore, after the gas turbine 1 is ignited, the low-pressure economizer inlet temperature control valve 32 is controlled to open.

このときの、低圧節炭器入口温度調節弁３２の開度の時間的な変化の一例をグラフ３１１に示す。 A graph 311 shows an example of a temporal change in the degree of opening of the low-pressure economizer inlet temperature control valve 32 at this time.

本図に示すように、ガスタービン１点火後、低圧節炭器入口温度調節弁３２は開かれる（３１２）。しかし、低圧節炭器９の給水出口温度が低いため、低圧節炭器入口温度調節弁３２が全開となっても、低圧節炭器９の給水入口温度は水温規定値まで上昇しない状態が継続する（３１３）。 As shown in the figure, after ignition of the gas turbine 1, the low pressure economizer inlet temperature control valve 32 is opened (312). However, since the feed water outlet temperature of the low-pressure economizer 9 is low, even if the low-pressure economizer inlet temperature control valve 32 is fully opened, the state where the feed water inlet temperature of the low-pressure economizer 9 does not rise to the specified water temperature continues. (313).

低圧節炭器９内の給水が加熱され、低圧節炭器９の給水出口温度が上昇し、低圧節炭器９の給水入口温度が水温規定値に達した場合、低圧節炭器入口温度調節弁３２の開度を絞り（３１４）、低圧節炭器９の給水入口温度が水温規定値になるよう制御する。 When the feed water in the low-pressure economizer 9 is heated, the feed water outlet temperature of the low-pressure economizer 9 rises, and the feed water inlet temperature of the low-pressure economizer 9 reaches a water temperature specified value, the low-pressure economizer inlet temperature is adjusted. The degree of opening of the valve 32 is throttled (314), and the temperature of the feed water inlet of the low-pressure economizer 9 is controlled so as to reach the water temperature specified value.

本実施形態の貫流式排熱回収ボイラ２ａおよび従来の貫流式排熱回収ボイラ２の低圧節炭器９の給水入口温度の変化の様子を、図３（ｂ）に示す。図３（ｂ）において、グラフ３２１は、本実施形態の貫流式排熱回収ボイラ２ａの給水入口温度の変化を示すグラフであり、グラフ３３１は、従来の貫流式排熱回収ボイラ２の給水入口温度の変化を示すグラフである。なお、グラフ３４１は、後述の第三の実施形態の貫流式排熱回収ボイラ２ｃの給水入口温度の変化を示すグラフである。 FIG. 3(b) shows how the feed water inlet temperature of the low-pressure economizer 9 of the once-through heat recovery steam generator 2a of the present embodiment and the conventional once-through heat recovery boiler 2 changes. In FIG. 3(b), graph 321 is a graph showing changes in the feed water inlet temperature of the once-through heat recovery steam generator 2a of the present embodiment, and graph 331 is the feed water inlet temperature of the conventional once-through heat recovery boiler 2. It is a graph which shows a change of temperature. A graph 341 is a graph showing changes in the feed water inlet temperature of the once-through heat recovery boiler 2c of the third embodiment, which will be described later.

本実施形態では、高圧汽水分離器２２からの飽和水を低圧節炭器９の入口配管へ循環させる。従って、低圧節炭器９の給水出口温度よりも高温の給水が、起動初期より低圧節炭器９に供給される。このため、図３（ｂ）に示すように、低圧節炭器９にて加熱された給水のみにより低圧節炭器９の給水入口温度を上昇させる従来の貫流式排熱回収ボイラ２に比べて、低圧節炭器９の給水入口温度を早く上昇させることができる。 In this embodiment, the saturated water from the high-pressure steam separator 22 is circulated to the inlet pipe of the low-pressure economizer 9 . Therefore, water having a higher temperature than the water supply outlet temperature of the low-pressure economizer 9 is supplied to the low-pressure economizer 9 from the initial stage of startup. For this reason, as shown in FIG. , the feed water inlet temperature of the low-pressure economizer 9 can be raised quickly.

なお、上記例では、本実施形態の入口温度調節弁開閉制御部２１４は、蒸発器循環流量調節弁２９が閉じられている間のみ、低圧節炭器入口温度調節弁３２の開度を制御しているが、これに限定されない。例えば、蒸発器循環流量が低下し、低圧節炭器９の給水入口温度が水温規定値まで低下した場合、蒸発器循環流量調節弁２９を開いている間であっても、低圧節炭器入口温度調節弁３２を開くよう制御してもよい。 In the above example, the inlet temperature control valve opening/closing control unit 214 of the present embodiment controls the opening degree of the low-pressure economizer inlet temperature control valve 32 only while the evaporator circulation flow rate control valve 29 is closed. but not limited to. For example, when the evaporator circulation flow rate drops and the feed water inlet temperature of the low-pressure economizer 9 drops to the water temperature specified value, even while the evaporator circulation flow control valve 29 is open, the low-pressure economizer inlet You may control so that the temperature control valve 32 may be opened.

本実施形態のコントローラ２００は、さらに、運転圧力判別部２１５、水位検出部２１６、および、高圧給水調節弁制御部２１７を備える。 The controller 200 of this embodiment further includes an operating pressure determination section 215 , a water level detection section 216 , and a high pressure water supply control valve control section 217 .

運転圧力判別部２１５は、高圧蒸発器２１の蒸気出口圧力が低圧節炭器９の給水入口圧力より高いか否かを判別する。運転圧力判別部２１５は、高圧蒸発器２１の蒸気出口、低圧節炭器９の給水入口にそれぞれ設けられた圧力センサ３９からの出力を用い、この判別を行う。運転圧力判別部２１５は、ガスタービン１に点火後、各圧力をモニタし、上記条件を満たした場合、循環流量調節弁開閉制御部２１２に、制御信号を出力する。 The operating pressure determination unit 215 determines whether or not the steam outlet pressure of the high pressure evaporator 21 is higher than the feed water inlet pressure of the low pressure economizer 9 . The operating pressure determination unit 215 performs this determination using the output from the pressure sensors 39 provided at the steam outlet of the high-pressure evaporator 21 and the water supply inlet of the low-pressure economizer 9, respectively. After the gas turbine 1 is ignited, the operating pressure determination unit 215 monitors each pressure, and outputs a control signal to the circulation flow control valve opening/closing control unit 212 when the above conditions are satisfied.

本実施形態では、循環流量調節弁開閉制御部２１２は、運転圧力判別部２１５から、制御信号を受信後、蒸発器循環流量調節弁２９を開く、開度信号の出力を開始する。すなわち、本実施形態の循環流量調節弁開閉制御部２１２は、起動後、高圧蒸発器２１の蒸気出口圧力が、低圧節炭器９の給水入口圧力よりも高くなったことを確認後、蒸発器循環流量調節弁２９に対し、開指示を与える。 In this embodiment, after receiving the control signal from the operating pressure determination unit 215 , the circulation flow control valve opening/closing control unit 212 starts outputting an opening degree signal for opening the evaporator circulation flow control valve 29 . That is, after starting, the circulation flow control valve opening/closing control unit 212 of the present embodiment confirms that the steam outlet pressure of the high-pressure evaporator 21 is higher than the feed water inlet pressure of the low-pressure economizer 9, and then An open instruction is given to the circulation flow control valve 29 .

水位検出部２１６は、高圧汽水分離器２２の水位を検出する。水位検出部２１６は、高圧汽水分離器２２の水位センサ４０の出力をモニタし、モニタ結果を、高圧給水調節弁制御部２１７に出力する。 The water level detector 216 detects the water level of the high pressure steam separator 22 . The water level detection unit 216 monitors the output of the water level sensor 40 of the high pressure steam separator 22 and outputs the monitoring result to the high pressure water supply control valve control unit 217 .

高圧給水調節弁制御部２１７は、高圧汽水分離器２２の水位が予め定めた規定値（水位規定値）となるよう、高圧給水調節弁２０の開度を制御し、高中圧給水ライン３５の流量を調整する。高圧給水調節弁制御部２１７は、例えば、循環流量調節弁開閉制御部２１２同様、比例積分調節器等で実現される。 The high-pressure water supply control valve control unit 217 controls the opening of the high-pressure water supply control valve 20 so that the water level of the high-pressure steam separator 22 becomes a predetermined specified value (water level specified value), and the flow rate of the high and intermediate pressure water supply line 35 to adjust. The high-pressure water supply control valve control unit 217 is realized by, for example, a proportional-integral control unit or the like, like the circulation flow rate control valve opening/closing control unit 212 .

なお、蒸発器循環運転時に高圧汽水分離器２２の水位が水位設定値よりも上昇した場合は、起動ブロー弁２７を開き、高圧汽水分離器２２内の飽和水を、復水器５へと排水するよう制御する。なお、このとき、ブローライン３８を介して、高圧汽水分離器２２内の飽和水を、ブロータンク２８へ排水するよう制御してもよい。 In addition, when the water level of the high-pressure steam separator 22 rises above the water level set value during the evaporator circulation operation, the start blow valve 27 is opened and the saturated water in the high-pressure steam separator 22 is discharged to the condenser 5. control to At this time, the saturated water in the high-pressure steam separator 22 may be drained to the blow tank 28 via the blow line 38 .

また、コントローラ２００は、ＣＰＵとメモリと記憶装置とを備えた情報処理装置で実現されてもよい。この場合、コントローラ２００が実現する各機能は、記憶装置に格納されたプログラムを、ＣＰＵがメモリにロードして実行することにより、実現される。 Also, the controller 200 may be realized by an information processing device that includes a CPU, a memory, and a storage device. In this case, each function realized by the controller 200 is realized by the CPU loading a program stored in the storage device into the memory and executing the program.

各処理に必要なデータは、処理途中および処理後に生成されるデータ等は、ＲＡＭ等のメモリまたはＲＯＭ等の記憶装置に格納される。上記例では、各規定値は、ＲＯＭ等に予め記憶される。また、流量、水温、水位等のモニタ結果は、ＲＡＭ等に一時的に記憶されてもよいし、ＲＯＭ等に記憶されてもよい。 Data necessary for each process, data generated during and after the process, and the like are stored in a memory such as a RAM or a storage device such as a ROM. In the above example, each specified value is pre-stored in the ROM or the like. Further, the monitoring results of the flow rate, water temperature, water level, etc. may be temporarily stored in RAM or the like, or may be stored in ROM or the like.

また、コントローラ２００の各機能は、比例積分調節器等、加算器、減算器、比較器、積分微分器、関数発生器等のハードウェアの組み合わせで実現されてもよい。 Also, each function of the controller 200 may be implemented by a combination of hardware such as a proportional-integral controller, an adder, a subtractor, a comparator, an integral-differentiator, a function generator, and the like.

このように、本実施形態によれば、高圧汽水分離器２２の飽和水を、低圧節炭器９の入口に戻す蒸発器循環ライン２４ａを備える。そして、蒸発器循環ライン２４ａに設けられた蒸発器循環流量調節弁２９の開閉を、高圧蒸発器２１の入口に設けられた高圧蒸発器入口給水流量計３３が検出した流量に応じて制御する。 As described above, according to this embodiment, the evaporator circulation line 24 a is provided to return the saturated water of the high pressure steam separator 22 to the inlet of the low pressure economizer 9 . Then, opening and closing of the evaporator circulation flow control valve 29 provided in the evaporator circulation line 24a is controlled according to the flow rate detected by the high pressure evaporator inlet feed water flow meter 33 provided at the inlet of the high pressure evaporator 21 .

高圧系４１内の圧力は、低圧系４３内の圧力よりも十分に高い。このため、飽和水量が不足するような場合であっても、圧力差で高圧汽水分離器２２内の飽和水を前流側の系統へと循環させることができる。すなわち、高圧系４１内で自然循環バランスが成立しない状態であっても、低圧系４３を経由して高圧蒸発器２１への給水を継続できる。これにより、本実施形態によれば、どのような状態であっても、高圧蒸発器２１が異常加熱することがなく、安定した蒸発器循環運転を維持できる。従って、本実施形態によれば、強制的に飽和水を循環させるための蒸発器循環ポンプ２５（図７（ｂ）参照）が不要になり、コストを抑えられる。 The pressure within the high pressure system 41 is sufficiently higher than the pressure within the low pressure system 43 . Therefore, even if the amount of saturated water is insufficient, the pressure difference allows the saturated water in the high-pressure steam separator 22 to be circulated to the system on the upstream side. That is, even if the natural circulation balance is not established within the high-pressure system 41, the water supply to the high-pressure evaporator 21 can be continued via the low-pressure system 43. As a result, according to this embodiment, the high-pressure evaporator 21 does not overheat under any conditions, and a stable evaporator circulation operation can be maintained. Therefore, according to this embodiment, the evaporator circulation pump 25 (see FIG. 7(b)) for forcibly circulating the saturated water becomes unnecessary, and the cost can be suppressed.

また、本実施形態によれば、高圧汽水分離器２２の飽和水が、低圧節炭器９に給水される。すなわち、高圧汽水分離器２２の飽和水の熱エネルギが低圧系４３の熱エネルギとして置き換わる。このため、熱の損失を抑制でき、補給水が増加することもない。 Further, according to this embodiment, the saturated water of the high-pressure steam separator 22 is supplied to the low-pressure economizer 9 . That is, the heat energy of the saturated water in the high-pressure steam separator 22 replaces the heat energy in the low-pressure system 43 . For this reason, heat loss can be suppressed, and supplementary water does not increase.

また、一般に、排ガス入熱のない停止時には低圧節炭器９の管内給水の温度は低下する。このため、起動初期は低圧節炭器９の給水入口温度が露点温度以下となり、排ガス中の水分が低圧節炭器９の管外面で結露する。 Moreover, generally, the temperature of the water supply in the pipe of the low-pressure economizer 9 decreases when the engine is stopped with no exhaust gas heat input. For this reason, the feed water inlet temperature of the low-pressure economizer 9 becomes lower than the dew point temperature at the initial stage of start-up, and moisture in the exhaust gas condenses on the pipe outer surface of the low-pressure economizer 9 .

上述のように、従来の貫流式排熱回収ボイラ２では、起動初期から、節炭器再循環ライン１４により、低圧節炭器９の出口の給水を入口側へ再循環させる。これにより、低圧節炭器９の給水入口温度が上昇し、排ガス中の水分の結露による低圧節炭器９の外面の腐食の発生を抑制している。 As described above, in the conventional once-through heat recovery boiler 2, the feed water from the outlet of the low-pressure economizer 9 is recirculated to the inlet side by the economizer recirculation line 14 from the initial stage of startup. As a result, the temperature of the feed water inlet of the low-pressure economizer 9 rises, suppressing corrosion of the outer surface of the low-pressure economizer 9 due to condensation of moisture in the exhaust gas.

しかし、このような手法では、排ガスの最低温部に設置された低圧節炭器９の出口給水温度が上昇するまでには時間がかかる。例えば、図３（ｂ）に示すように、従来の貫流式排熱回収ボイラ２では、水分露点温度に到達するまで、Ｔ１の時間がかかる。この間の結露の発生は避けられない。 However, with such a method, it takes time until the outlet water temperature of the low-pressure economizer 9 installed in the lowest temperature part of the exhaust gas rises. For example, as shown in FIG. 3B, in the conventional once-through heat recovery boiler 2, it takes time T1 to reach the water dew point temperature. The occurrence of dew condensation during this period is unavoidable.

しかしながら、本実施形態では、起動初期から、高圧汽水分離器２２の飽和水が、低圧節炭器９に給水される。このため、低圧節炭器出口給水のみを加温に使用する従来の貫流式排熱回収ボイラ２に比べて、低圧節炭器９の給水入口温度を早く上昇させることができる。例えば、図３（ｂ）の例では、Ｔ１より大幅に短い時間Ｔ３で水分露点温度に到達する。 However, in this embodiment, the saturated water of the high-pressure steam separator 22 is supplied to the low-pressure economizer 9 from the initial stage of startup. Therefore, compared to the conventional once-through heat recovery boiler 2 that uses only the low-pressure economizer outlet feed water for heating, the feed water inlet temperature of the low-pressure economizer 9 can be raised faster. For example, in the example of FIG. 3B, the moisture dew point temperature is reached in a time T3 significantly shorter than T1.

その結果、本実施形態によれば、低圧節炭器９の管外面で排ガス中の水分が結露する時間が大幅に減少し、それに伴い、低圧節炭器９の管外面の腐食を低減できる。 As a result, according to the present embodiment, the time for moisture in the exhaust gas to condense on the outer surface of the low-pressure economizer 9 can be significantly reduced, thereby reducing corrosion of the outer surface of the low-pressure economizer 9 .

従って、本実施形態によれば、貫流式排熱回収ボイラ２ａにおいて、コストの上昇とエネルギの損失とを抑えつつ、起動時における安定した蒸発器循環運転を実現できる。これにより、貫流式排熱回収ボイラ２ａの経済性と信頼性とが向上する。 Therefore, according to the present embodiment, in the once-through heat recovery boiler 2a, stable evaporator circulation operation can be realized at the time of start-up while suppressing an increase in cost and loss of energy. This improves the economic efficiency and reliability of the once-through heat recovery boiler 2a.

＜変形例１＞
なお、図１（ｂ）に示すように、高中圧給水ライン３５から蒸発器循環ライン２４ａへ給水を供給する、循環水減温ライン３０をさらに備えてもよい。循環水減温ライン３０は、高中圧給水ライン３５の高中圧給水ポンプ１３の出口と、高圧給水調節弁２０との間で高中圧給水ライン３５から分岐し、蒸発器循環流量調節弁２９の手前で蒸発器循環ライン２４ａに接続される。循環水減温ライン３０には、蒸発器循環水減温水調節弁３１が設けられる。 <Modification 1>
In addition, as shown in FIG. 1(b), a circulating water reducing temperature line 30 may be further provided for supplying water from the high/intermediate pressure water supply line 35 to the evaporator circulation line 24a. The circulating water reducing temperature line 30 branches from the high and intermediate pressure water supply line 35 between the outlet of the high and intermediate pressure water supply pump 13 of the high and intermediate pressure water supply line 35 and the high pressure water supply control valve 20, and is before the evaporator circulation flow control valve 29. is connected to the evaporator circulation line 24a. An evaporator circulating water reducing temperature control valve 31 is provided in the circulating water reducing temperature line 30 .

高圧汽水分離器２２内の飽和水の温度の変動が大きい場合、蒸発器循環流量調節弁２９での減圧により、蒸発器循環ライン２４内の飽和水が気液二相流体となる可能性がある。気液二相流体となった場合、接続先の低圧節炭器９の入口の低温水と混合されることにより、ウォータハンマ現象が発生する。 If the temperature of the saturated water in the high-pressure steam separator 22 fluctuates significantly, the saturated water in the evaporator circulation line 24 may become a gas-liquid two-phase fluid due to the pressure reduction in the evaporator circulation flow control valve 29. . When it becomes a gas-liquid two-phase fluid, it is mixed with the low-temperature water at the inlet of the low-pressure economizer 9 to which it is connected, thereby causing a water hammer phenomenon.

本変形例では、循環水減温ライン３０を設け、高圧汽水分離器２２からの飽和水に高中圧給水ポンプ１３の出口の給水を混合する。これにより、高圧汽水分離器２２からの飽和水は低圧節炭器９の入口給水の飽和温度未満まで減温される。このように、本変形例によれば、蒸発器循環流量調節弁２９により減圧されても、蒸発器循環ライン２４内の飽和水が気液二相流体となる可能性は減り、ウォータハンマ現象の発生を低減できる。 In this modification, a circulating water desuperheating line 30 is provided, and the saturated water from the high-pressure steam separator 22 is mixed with the feed water at the outlet of the high/intermediate-pressure feed pump 13 . As a result, the temperature of the saturated water from the high-pressure steam separator 22 is reduced to below the saturation temperature of the inlet feed water of the low-pressure economizer 9 . Thus, according to this modification, even if the pressure is reduced by the evaporator circulation flow control valve 29, the possibility that the saturated water in the evaporator circulation line 24 becomes a gas-liquid two-phase fluid is reduced, and the water hammer phenomenon occurs. Occurrence can be reduced.

＜変形例２＞
なお、本実施形態では、低圧節炭器９の出口に高中圧給水ライン３５を設け、低圧節炭器９から高圧系４１および中圧系４２へ給水を供給している。しかし、高圧系および中圧系への給水の供給は、これに限定されない。例えば、図４に示すように、低圧ドラム１０に高中圧給水ライン３５を接続し、低圧ドラム１０から供給してもよい。なお、図４では、循環水減温ライン３０と蒸発器循環水減温水調節弁３１とを備える場合を例示するが、上記実施形態同様、これらはなくてもよい。 <Modification 2>
In addition, in this embodiment, the outlet of the low-pressure economizer 9 is provided with a high-intermediate-pressure water supply line 35 to supply water from the low-pressure economizer 9 to the high-pressure system 41 and the intermediate-pressure system 42 . However, the supply of water to the high-pressure system and the medium-pressure system is not limited to this. For example, as shown in FIG. 4 , a high and intermediate pressure water supply line 35 may be connected to the low pressure drum 10 to supply water from the low pressure drum 10 . Although FIG. 4 illustrates the case where the circulating water desuperheating line 30 and the evaporator circulating water desuperheating control valve 31 are provided, they may be omitted as in the above embodiment.

＜＜第二の実施形態＞＞
次に、本発明の第二の実施形態を説明する。本実施形態では、蒸発器循環ライン２４を、高圧汽水分離器２２から高圧系４１よりも低圧となる系に設置された蒸気ドラムに接続する。本実施形態では、特に、中圧系４２の蒸気ドラムである中圧ドラム１６に接続する。 <<Second Embodiment>>
Next, a second embodiment of the invention will be described. In this embodiment, the evaporator circulation line 24 is connected from the high-pressure steam separator 22 to a steam drum installed in a system having a lower pressure than the high-pressure system 41 . In this embodiment, in particular, it is connected to the intermediate pressure drum 16 which is the steam drum of the intermediate pressure system 42 .

図５は、本実施形態の貫流式排熱回収ボイラ２ｂの一例を示す図である。本実施形態の貫流式排熱回収ボイラ２ｂにおいて、蒸発器循環ライン２４ｂは、高圧汽水分離器２２の出口に接続された下降管から分岐し、中圧ドラム１６に接続される。また、蒸発器循環ライン２４ｂには、蒸発器循環流量調節弁２９が設けられる。 FIG. 5 is a diagram showing an example of the once-through heat recovery boiler 2b of this embodiment. In the once-through heat recovery steam generator 2b of the present embodiment, the evaporator circulation line 24b branches from a downcomer connected to the outlet of the high pressure steam separator 22 and is connected to the intermediate pressure drum 16 . An evaporator circulation flow control valve 29 is provided in the evaporator circulation line 24b.

本実施形態の貫流式排熱回収ボイラ２ｂも、コントローラ２００を備える。本実施形態のコントローラ２００による、蒸発器循環流量調節弁２９および高圧給水調節弁２０の開閉制御については、第一の実施形態と同様である。 The once-through heat recovery boiler 2b of this embodiment also includes a controller 200. As shown in FIG. The opening/closing control of the evaporator circulation flow control valve 29 and the high-pressure feed water control valve 20 by the controller 200 of this embodiment is the same as in the first embodiment.

また、本実施形態のコントローラ２００による低圧節炭器入口温度調節弁３２の開閉制御も、基本的には、第一の実施形態と同様である。しかし、本実施形態では、蒸発器循環ライン２４ｂの接続先が、中圧ドラム１６である。このため、低圧節炭器入口温度調節弁３２の開閉は、蒸発器循環流量調節弁２９の開閉制御とは、独立に制御してもよい。 Further, the opening/closing control of the low-pressure economizer inlet temperature control valve 32 by the controller 200 of this embodiment is basically the same as that of the first embodiment. However, in the present embodiment, the connection destination of the evaporator circulation line 24b is the intermediate pressure drum 16 . Therefore, the opening/closing of the low-pressure economizer inlet temperature control valve 32 may be controlled independently of the opening/closing control of the evaporator circulation flow rate control valve 29 .

このように、本実施形態では、高圧汽水分離器２２の飽和水を、中圧ドラム１６に戻す蒸発器循環ライン２４ｂを備える。そして、蒸発器循環ライン２４ｂに設けられた蒸発器循環流量調節弁２９の開閉を、高圧蒸発器２１の入口に設けられた高圧蒸発器入口給水流量計３３が検出した流量に応じて制御する。 Thus, in this embodiment, the evaporator circulation line 24 b is provided to return the saturated water from the high-pressure steam separator 22 to the intermediate-pressure drum 16 . Then, opening and closing of the evaporator circulation flow control valve 29 provided in the evaporator circulation line 24b is controlled according to the flow rate detected by the high pressure evaporator inlet feed water flow meter 33 provided at the inlet of the high pressure evaporator 21.

高圧系４１内の圧力は、中圧ドラム１６内の圧力より十分に高い。このため、本実施形態においても、圧力差で高圧汽水分離器２２内の飽和水を前流側の系統へと循環させることができる。すなわち、高圧系４１内で自然循環バランスが成立しない状態であっても、中圧系４２を経由して高圧蒸発器２１への給水を継続できる。これにより、本実施形態によれば、どのような状態であっても、高圧蒸発器２１が異常加熱することがなく、安定した蒸発器循環運転を実現できる。従って、本実施形態によれば、強制的に飽和水を循環させるための蒸発器循環ポンプ２５の設置が不要になり、コストを抑えられる。 The pressure within the high pressure system 41 is sufficiently higher than the pressure within the intermediate pressure drum 16 . Therefore, also in this embodiment, the saturated water in the high-pressure steam separator 22 can be circulated to the system on the upstream side by the pressure difference. That is, even if the natural circulation balance is not established within the high-pressure system 41, water supply to the high-pressure evaporator 21 via the medium-pressure system 42 can be continued. As a result, according to this embodiment, the high-pressure evaporator 21 does not overheat under any conditions, and stable evaporator circulation operation can be achieved. Therefore, according to this embodiment, it is unnecessary to install the evaporator circulation pump 25 for forcibly circulating the saturated water, and the cost can be reduced.

また、本実施形態の貫流式排熱回収ボイラ２ｂでは、高圧蒸発器系の給水を、中圧系４２に循環させる。中圧系４２は、低圧系４３より運転圧力が高く、ガス前流側に設置される。このため、低圧系４３に循環させる構成に比べて、減圧による回収熱の損失を抑制することができる。 In addition, in the once-through heat recovery boiler 2b of the present embodiment, the feed water of the high-pressure evaporator system is circulated to the medium-pressure system 42. As shown in FIG. The intermediate pressure system 42 has a higher operating pressure than the low pressure system 43 and is installed on the upstream side of the gas. For this reason, loss of recovered heat due to pressure reduction can be suppressed as compared with a configuration in which the refrigerant is circulated through the low-pressure system 43 .

また、接続先が、気液分離可能な蒸気ドラムであるため、蒸発器循環流量調節弁２９での減圧により気液二相状態となった流体であっても、そのままの状態で受け入れることができ、循環を継続できる。このため、本実施形態では、第一の実施形態のような循環水減温ライン３０の設置は不要となる。 In addition, since the connection destination is a steam drum capable of gas-liquid separation, even if the fluid is in a gas-liquid two-phase state due to the pressure reduction in the evaporator circulation flow control valve 29, it can be received as it is. , can continue to circulate. Therefore, in this embodiment, installation of the circulating water reducing temperature line 30 as in the first embodiment is not required.

なお、本実施形態においても、第一の実施形態同様、高圧系４１および中圧系４２への給水を、低圧ドラム１０から行うよう構成してもよい。すなわち、低圧ドラム１０に高中圧給水ライン３５を接続してもよい。 Also in this embodiment, water supply to the high-pressure system 41 and the intermediate-pressure system 42 may be performed from the low-pressure drum 10 as in the first embodiment. That is, the high and medium pressure water supply line 35 may be connected to the low pressure drum 10 .

＜＜第三の実施形態＞＞
次に、本発明の第三の実施形態を説明する。本実施形態でも、蒸発器循環ライン２４を、高圧汽水分離器２２から高圧系４１よりも低圧となる系に設置された蒸気ドラムに接続する。本実施形態では、特に、低圧系４３の蒸気ドラムである低圧ドラム１０に接続する。 <<Third Embodiment>>
Next, a third embodiment of the invention will be described. Also in this embodiment, the evaporator circulation line 24 is connected from the high-pressure steam separator 22 to a steam drum installed in a system having a lower pressure than the high-pressure system 41 . In this embodiment, in particular, it is connected to the low pressure drum 10 which is the steam drum of the low pressure system 43 .

図６（ａ）は、本実施形態の貫流式排熱回収ボイラ２ｃの一例を示す図である。本実施形態の貫流式排熱回収ボイラ２ｃにおいて、蒸発器循環ライン２４ｃは、高圧汽水分離器２２の出口に接続された下降管から分岐し、低圧ドラム１０に接続される。また、蒸発器循環ライン２４ｃは、蒸発器循環流量調節弁２９を備える。 FIG. 6(a) is a diagram showing an example of the once-through heat recovery boiler 2c of the present embodiment. In the once-through heat recovery steam generator 2c of the present embodiment, the evaporator circulation line 24c branches from a downcomer pipe connected to the outlet of the high pressure steam separator 22 and is connected to the low pressure drum 10 . Also, the evaporator circulation line 24 c is provided with an evaporator circulation flow control valve 29 .

また、本実施形態のコントローラ２００による、蒸発器循環流量調節弁２９および高圧給水調節弁２０の開閉制御についても、第一の実施形態と同様である。 The opening/closing control of the evaporator circulation flow control valve 29 and the high-pressure feed water control valve 20 by the controller 200 of this embodiment is also the same as in the first embodiment.

また、本実施形態のコントローラ２００による低圧節炭器入口温度調節弁３２の開閉制御も、基本的には、第一の実施形態と同様である。しかし、本実施形態では、蒸発器循環ライン２４ｃの接続先が、低圧ドラム１０である。このため、低圧節炭器入口温度調節弁３２の開閉は、蒸発器循環流量調節弁２９の開閉制御とは、独立に制御してもよい。 Further, the opening/closing control of the low-pressure economizer inlet temperature control valve 32 by the controller 200 of this embodiment is basically the same as that of the first embodiment. However, in this embodiment, the connection destination of the evaporator circulation line 24 c is the low pressure drum 10 . Therefore, the opening/closing of the low-pressure economizer inlet temperature control valve 32 may be controlled independently of the opening/closing control of the evaporator circulation flow rate control valve 29 .

このように、本実施形態では、高圧汽水分離器２２の飽和水を、低圧ドラム１０に戻す蒸発器循環ライン２４ｃを備える。そして、蒸発器循環ライン２４ｃに設けられた蒸発器循環流量調節弁２９の開閉を、高圧蒸発器２１の入口に設けられた高圧蒸発器入口給水流量計３３が検出した流量に応じて制御する。 Thus, in this embodiment, the evaporator circulation line 24c for returning the saturated water of the high-pressure steam separator 22 to the low-pressure drum 10 is provided. Then, opening and closing of the evaporator circulation flow control valve 29 provided in the evaporator circulation line 24c is controlled according to the flow rate detected by the high pressure evaporator inlet feed water flow meter 33 provided at the inlet of the high pressure evaporator 21.

本実施形態においても、高圧系４１内の圧力は、低圧ドラム１０内の圧力より十分に高いた。このため、圧力差で高圧汽水分離器２２内の飽和水を、前流側の系統へと循環させることができる。すなわち、高圧系４１内で自然循環バランスが成立しない状態であっても、低圧系４３を経由して高圧蒸発器２１への給水を継続できる。これにより、本実施形態によれば、どのような状態であっても、高圧蒸発器２１の異常加熱も発生することがなく、安定した蒸発器循環運転を実現できる。従って、本実施形態によれば、強制的に飽和水を循環させるための蒸発器循環ポンプ２５が不要になり、コストを抑えられる。 Also in this embodiment, the pressure in the high pressure system 41 was sufficiently higher than the pressure in the low pressure drum 10 . Therefore, the saturated water in the high-pressure steam separator 22 can be circulated to the system on the upstream side due to the pressure difference. That is, even if the natural circulation balance is not established within the high-pressure system 41, the water supply to the high-pressure evaporator 21 can be continued via the low-pressure system 43. As a result, according to the present embodiment, no abnormal heating of the high-pressure evaporator 21 occurs, and stable evaporator circulation operation can be realized in any state. Therefore, according to this embodiment, the evaporator circulation pump 25 for forcibly circulating the saturated water becomes unnecessary, and the cost can be suppressed.

また、低圧ドラム１０へ循環する高圧汽水分離器２２の飽和水は、低圧ドラム１０の缶水よりも高エンタルピである。起動時にこの飽和水を受け入れることにより、低圧ドラム１０の圧力および飽和温度は早く上昇する。その結果、低圧節炭器９の入口側ガス温度の上昇も早くなり、低圧節炭器９での熱吸収量が急速に増加するため、低圧節炭器９の給水出口温度も早く上昇する。 Also, the saturated water of the high-pressure steam separator 22 circulating to the low-pressure drum 10 has a higher enthalpy than the boiled water of the low-pressure drum 10 . By accepting this saturated water at start-up, the pressure and saturation temperature of the low pressure drum 10 rises quickly. As a result, the gas temperature on the inlet side of the low-pressure economizer 9 rises quickly, and the amount of heat absorbed by the low-pressure economizer 9 rapidly increases, so the water supply outlet temperature of the low-pressure economizer 9 also rises quickly.

そして、このような低圧節炭器９の出口給水を、節炭器再循環ライン１４により低圧節炭器９の入口側へ再循環させることで、低圧節炭器９の給水入口温度を早く上昇させることができる。 By recirculating such outlet water supply of the low-pressure economizer 9 to the inlet side of the low-pressure economizer 9 through the economizer recirculation line 14, the temperature of the water supply inlet of the low-pressure economizer 9 is quickly increased. can be made

例えば、本実施形態の貫流式排熱回収ボイラ２ａでは、図３（ｂ）のグラフ３４１で示すように低圧節炭器９の給水入口温度が変化する。図３（ｂ）の例では、時間Ｔ２で水分露点温度に到達する。このように、本実施形態によれば、低圧節炭器出口給水のみを加温に使用する従来の貫流式排熱回収ボイラ２に比べて、低圧節炭器９の給水入口温度が早く上昇する。その結果、本実施形態によれば、低圧節炭器９の管外面で排ガス中の水分が結露する時間が減少し、それに伴い、低圧節炭器９の管外面の腐食を低減できる。 For example, in the once-through heat recovery boiler 2a of the present embodiment, the feedwater inlet temperature of the low-pressure economizer 9 changes as shown by the graph 341 in FIG. 3(b). In the example of FIG. 3B, the moisture dew point temperature is reached at time T2. Thus, according to the present embodiment, the temperature at the feed water inlet of the low-pressure economizer 9 rises faster than in the conventional once-through heat recovery boiler 2 that uses only the low-pressure economizer outlet feed water for heating. . As a result, according to the present embodiment, the time for moisture in the exhaust gas to condense on the outer surface of the low-pressure economizer 9 is reduced, and corrosion of the outer surface of the low-pressure economizer 9 can be reduced.

＜変形例＞
なお、本実施形態においても、図６（ｂ）に示すように、第一の実施形態同様、高圧系４１および中圧系４２への給水を、低圧ドラム１０から行うよう構成してもよい。すなわち、低圧ドラム１０に高中圧給水ライン３５を接続してもよい。 <Modification>
Also in this embodiment, as shown in FIG. 6B, water supply to the high-pressure system 41 and the intermediate-pressure system 42 may be performed from the low-pressure drum 10, as in the first embodiment. That is, the high and medium pressure water supply line 35 may be connected to the low pressure drum 10 .

特に、本変形例によれば、低圧ドラム１０内の水温が上昇する。このため、中圧系４２および高圧系４１へ供給される給水温度が上昇する。これにより、中圧系４２および高圧系４１が温められ、起動時の急激な温度変化に伴う熱疲労等の発生が低減する。 In particular, according to this modified example, the water temperature in the low-pressure drum 10 rises. Therefore, the temperature of the feed water supplied to the intermediate pressure system 42 and the high pressure system 41 rises. As a result, the intermediate pressure system 42 and the high pressure system 41 are warmed, and the occurrence of thermal fatigue or the like due to a sudden temperature change at startup is reduced.

さらに、第三の実施形態と同様に、低圧節炭器９の給水入口温度の上昇も早くなり、低圧節炭器９の管外面の腐食を低減できる。 Furthermore, similarly to the third embodiment, the temperature at the feed water inlet of the low-pressure economizer 9 rises quickly, and corrosion of the pipe outer surface of the low-pressure economizer 9 can be reduced.

以上説明したように、各実施形態および変形例によれば、高圧汽水分離器２２からの蒸発器循環ライン２４（２４ａ～２４ｃ）の接続先を、中圧系４２および低圧系４３のいずれかの構成にする。これにより、起動時等であっても、回収熱や補給水の損失なしに、蒸発器循環ポンプ２５を設置することなく、高圧蒸発器２１への給水を継続でき、安定した蒸発器循環運転を行うことができる。従って、経済性に優れた貫流式排熱回収ボイラを提供できる。また、接続先によっては、低圧節炭器９の入口側での結露による外面腐食の発生を抑制し、信頼性も向上する。 As described above, according to each of the embodiments and modifications, the evaporator circulation line 24 (24a to 24c) from the high-pressure steam separator 22 is connected to either the medium-pressure system 42 or the low-pressure system 43. Make configuration. As a result, even during start-up or the like, water supply to the high-pressure evaporator 21 can be continued without loss of recovered heat or make-up water, without installing the evaporator circulation pump 25, and stable evaporator circulation operation can be performed. It can be carried out. Therefore, it is possible to provide an economical once-through heat recovery boiler. In addition, depending on the connection destination, occurrence of corrosion of the outer surface due to dew condensation on the inlet side of the low-pressure economizer 9 is suppressed, and reliability is also improved.

１：ガスタービン、２：貫流式排熱回収ボイラ、２ａ：貫流式排熱回収ボイラ、２ｂ：貫流式排熱回収ボイラ、２ｃ：貫流式排熱回収ボイラ、３：蒸気タービン、４：発電機、５：復水器、６：復水ポンプ、７：復水脱塩装置、８：低圧給水ポンプ、９：低圧節炭器、１０：低圧ドラム、１１：低圧蒸発器、１２：低圧過熱器、１３：高中圧給水ポンプ、１４：節炭器再循環ライン、１５：中圧節炭器、１６：中圧ドラム、１７：中圧蒸発器、１８：中圧過熱器、１９：高圧節炭器、２０：高圧給水調節弁、２１：高圧蒸発器、２２：高圧汽水分離器、２３：高圧過熱器、２４：蒸発器循環ライン、２４ａ：蒸発器循環ライン、２４ｂ：蒸発器循環ライン、２４ｃ：蒸発器循環ライン、２５：蒸発器循環ポンプ、２６：起動ブローライン、２７：起動ブロー弁、２８：ブロータンク、２９：蒸発器循環流量調節弁、３０：循環水減温ライン、３１：蒸発器循環水減温水調節弁、３２：低圧節炭器入口温度調節弁、３３：高圧蒸発器入口給水流量計、３４：低圧節炭器入口給水温度計、３５：高中圧給水ライン、３６：節炭器再循環ポンプ、３７：復水ライン、３８：ブローライン、３９：圧力センサ、４０：水位センサ、４１：高圧系、４２：中圧系、４３：低圧系、
１００：コンバインドサイクル発電設備、２００：コントローラ、２１１：流量検出部、２１２：循環流量調節弁開閉制御部、２１３：水温検出部、２１４：入口温度調節弁開閉制御部、２１５：運転圧力判別部、２１６：水位検出部、２１７：高圧給水調節弁制御部、
３０１：グラフ、３０２：グラフ、３１１：グラフ、３２１：グラフ、３３１：グラフ、３４１：グラフ 1: gas turbine, 2: once-through heat recovery boiler, 2a: once-through heat recovery boiler, 2b: once-through heat recovery boiler, 2c: once-through heat recovery boiler, 3: steam turbine, 4: generator , 5: Condenser, 6: Condensate pump, 7: Condensate demineralizer, 8: Low pressure feed water pump, 9: Low pressure economizer, 10: Low pressure drum, 11: Low pressure evaporator, 12: Low pressure superheater , 13: high and medium pressure feed water pump, 14: economizer recirculation line, 15: medium pressure economizer, 16: medium pressure drum, 17: medium pressure evaporator, 18: medium pressure superheater, 19: high pressure economizer device, 20: high-pressure feed water control valve, 21: high-pressure evaporator, 22: high-pressure steam separator, 23: high-pressure superheater, 24: evaporator circulation line, 24a: evaporator circulation line, 24b: evaporator circulation line, 24c : Evaporator circulation line, 25: Evaporator circulation pump, 26: Starting blow line, 27: Starting blow valve, 28: Blow tank, 29: Evaporator circulation flow control valve, 30: Circulating water reducing temperature line, 31: Evaporation Circulating water reducing water control valve, 32: Low pressure economizer inlet temperature control valve, 33: High pressure evaporator inlet feed water flow meter, 34: Low pressure economizer inlet feed water temperature gauge, 35: High and medium pressure water supply line, 36: Node coal recirculation pump, 37: condensate line, 38: blow line, 39: pressure sensor, 40: water level sensor, 41: high pressure system, 42: intermediate pressure system, 43: low pressure system,
100: Combined cycle power generation facility, 200: Controller, 211: Flow rate detection unit, 212: Circulation flow rate control valve opening/closing control unit, 213: Water temperature detection unit, 214: Inlet temperature control valve opening/closing control unit, 215: Operating pressure determination unit, 216: Water level detection unit, 217: High pressure water supply control valve control unit,
301: graph, 302: graph, 311: graph, 321: graph, 331: graph, 341: graph

Claims (5)

それぞれ、ガスタービンからの排ガスが流通する排ガス流路の上流側から下流側に順に過熱器、蒸発器および節炭器を有する高圧系、中圧系および低圧系を備え、前記中圧系および前記低圧系は、それぞれ蒸気ドラムを備え、前記高圧系は、汽水分離器を備える貫流式排熱回収ボイラであって、
前記汽水分離器の飽和水を、前記中圧系および前記低圧系のいずれかに戻す蒸発器循環ラインを備え、
前記蒸発器循環ラインは、前記汽水分離器の飽和水排出口に接続された下降管から分岐して前記低圧系の節炭器の入口配管に接続され、
前記低圧系から前記高圧系および前記中圧系へ給水を供給する高中圧給水ラインから分岐して前記蒸発器循環ラインに接続される循環水減温ラインをさらに備えること
を特徴とする貫流式排熱回収ボイラ。 A high-pressure system, an intermediate-pressure system, and a low-pressure system each having a superheater, an evaporator, and an economizer in order from the upstream side to the downstream side of an exhaust gas passage through which the exhaust gas from the gas turbine flows, and the intermediate-pressure system and the low-pressure system are provided. the low pressure systems each comprising a steam drum and the high pressure system being a once-through heat recovery boiler comprising a steam separator,
An evaporator circulation line returning the saturated water of the steam separator to either the intermediate pressure system or the low pressure system ,
The evaporator circulation line is branched from a descending pipe connected to the saturated water outlet of the steam separator and connected to the inlet pipe of the low-pressure economizer,
further comprising a circulating water desuperheating line branched from a high and intermediate pressure water supply line for supplying water from the low pressure system to the high pressure system and the intermediate pressure system and connected to the evaporator circulation line;
A once-through heat recovery boiler characterized by 請求項１記載の貫流式排熱回収ボイラであって、
前記高圧系および前記中圧系へは、前記低圧系の節炭器から給水が供給されること
を特徴とする貫流式排熱回収ボイラ。 The once-through heat recovery boiler according to claim 1 ,
A once-through heat recovery steam generator, wherein feed water is supplied from the low-pressure economizer to the high-pressure system and the intermediate-pressure system. 請求項１記載の貫流式排熱回収ボイラであって、
前記高圧系および前記中圧系へは、前記低圧系の蒸気ドラムから給水が供給されること
を特徴とする貫流式排熱回収ボイラ。 The once-through heat recovery boiler according to claim 1 ,
A once-through heat recovery boiler, wherein feed water is supplied from a steam drum of the low-pressure system to the high-pressure system and the intermediate-pressure system. それぞれ、ガスタービンからの排ガスが流通する排ガス流路の上流側から下流側に順に過熱器、蒸発器および節炭器を有する高圧系、中圧系および低圧系を備え、前記中圧系および前記低圧系は、それぞれ蒸気ドラムを備え、前記高圧系は、汽水分離器を備える貫流式排熱回収ボイラの制御システムであって、
前記貫流式排熱回収ボイラは、
前記汽水分離器の飽和水を、前記中圧系および前記低圧系のいずれかに戻す蒸発器循環ラインと、
前記高圧系の蒸発器の管内流量を計測する高圧蒸発器入口給水流量計と、
前記蒸発器循環ライン上に設けられる循環流量調節弁と、を備え、
起動時に、前記高圧蒸発器入口給水流量計で計測された前記管内流量が予め定めた流量規定値となるよう前記循環流量調節弁の開度を制御すること
を特徴とする貫流式排熱回収ボイラの制御システム。 A high-pressure system, an intermediate-pressure system, and a low-pressure system each having a superheater, an evaporator, and an economizer in order from the upstream side to the downstream side of an exhaust gas passage through which the exhaust gas from the gas turbine flows, and the intermediate-pressure system and the low-pressure system are provided. A control system for a once-through heat recovery steam generator, wherein the low pressure systems each comprise a steam drum, and the high pressure system comprises a steam separator,
The once-through heat recovery boiler is
an evaporator circulation line returning the saturated water of the steam separator to either the intermediate pressure system or the low pressure system;
a high-pressure evaporator inlet water flow meter for measuring the flow rate in the pipe of the high-pressure evaporator;
a circulation flow control valve provided on the evaporator circulation line,
A once-through heat recovery boiler characterized by controlling the opening degree of the circulation flow control valve so that the flow rate in the pipe measured by the high-pressure evaporator inlet feed water flow meter becomes a predetermined flow rate regulation value at the time of start-up. control system. 請求項４記載の貫流式排熱回収ボイラの制御システムであって、
前記貫流式排熱回収ボイラは、
前記低圧系の節炭器の出口から入口に水を再循環させる再循環ラインと、
前記再循環ライン上に設けられる入口温度調節弁と、をさらに備え、
前記循環流量調節弁が閉じられた後、前記低圧系の節炭器の給水入口温度が、予め定めた水温規定値となるよう前記入口温度調節弁の開度を制御すること
を特徴とする貫流式排熱回収ボイラの制御システム。 A control system for a once-through heat recovery boiler according to claim 4 ,
The once-through heat recovery boiler is
a recirculation line for recirculating water from the outlet to the inlet of the low-pressure system economizer;
an inlet temperature control valve provided on the recirculation line;
After the circulation flow rate control valve is closed, the opening of the inlet temperature control valve is controlled so that the temperature of the feed water at the inlet of the low-pressure economizer reaches a predetermined water temperature specified value. A control system for a heat recovery boiler.
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JP2008075966A (en) 2006-09-21 2008-04-03 Babcock Hitachi Kk Once-through exhaust heat recovery boiler
JP2009074726A (en) 2007-09-19 2009-04-09 Babcock Hitachi Kk Once-through exhaust heat recovery boiler
JP2016194396A (en) 2015-04-01 2016-11-17 三菱日立パワーシステムズ株式会社 Exhaust heat recovery system, and operating method of exhaust heat recovery system

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JP2008075966A (en) 2006-09-21 2008-04-03 Babcock Hitachi Kk Once-through exhaust heat recovery boiler
JP2009074726A (en) 2007-09-19 2009-04-09 Babcock Hitachi Kk Once-through exhaust heat recovery boiler
JP2016194396A (en) 2015-04-01 2016-11-17 三菱日立パワーシステムズ株式会社 Exhaust heat recovery system, and operating method of exhaust heat recovery system

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