JP5812873B2 - Combined cycle power plant - Google Patents

Combined cycle power plant Download PDF

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JP5812873B2
JP5812873B2 JP2012003797A JP2012003797A JP5812873B2 JP 5812873 B2 JP5812873 B2 JP 5812873B2 JP 2012003797 A JP2012003797 A JP 2012003797A JP 2012003797 A JP2012003797 A JP 2012003797A JP 5812873 B2 JP5812873 B2 JP 5812873B2
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valve
recovery
cooler
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water supply
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JP2013142357A (en
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耕史 畑田
耕史 畑田
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Mitsubishi Power Ltd
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Mitsubishi Hitachi Power Systems 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

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Description

本発明は、ガスタービン及び蒸気タービンによって発電機を駆動するコンバインドサイクル発電プラントに関する。   The present invention relates to a combined cycle power plant in which a generator is driven by a gas turbine and a steam turbine.

コンバインドサイクル発電プラントは、ガスタービン及び蒸気タービンを組み合わせたプラントであり、高いプラント効率を達成する発電方式として知られている。この発電プラントは、ガスタービンから排出される高温排ガスの排熱を利用して、排熱回収ボイラで蒸気を生成し、この蒸気によって蒸気タービンを駆動するようになっている。この種の発電プラントでは、ガスタービンが極めて高温になるので、動静翼やロータ等の高温部を冷却する必要がある。   A combined cycle power plant is a plant that combines a gas turbine and a steam turbine, and is known as a power generation system that achieves high plant efficiency. This power plant uses the exhaust heat of the high-temperature exhaust gas discharged from the gas turbine to generate steam with an exhaust heat recovery boiler, and drives the steam turbine with this steam. In this type of power plant, the gas turbine becomes extremely hot, so it is necessary to cool high-temperature parts such as moving blades and rotors.

そこで、特許文献１には、ガスタービンの圧縮機で生成された圧縮空気の一部をＴＣＡクーラ（Ｔｕｒｂｉｎｅ Ｃｏｏｌｉｎｇ Ａｉｒ Ｃｏｏｌｅｒ）によって冷却することでタービン冷却空気を生成し、このタービン冷却空気を用いてガスタービンの高温部を冷却することが記載されている。具体的には、特許文献１記載の技術では、ＴＣＡクーラにおいて、ガスタービンの圧縮機からの圧縮空気と、排熱回収ボイラの高圧ドラムに供給される高圧給水とを熱交換させて、圧縮空気を冷却してタービン冷却空気を生成する。これにより、単にタービン冷却空気を生成できるだけでなく、排熱回収ボイラにおける蒸気発生に大いに寄与する高圧給水に圧縮空気の熱を回収して、発電プラント全体の発電効率を向上させることができる。   Therefore, in Patent Document 1, turbine cooling air is generated by cooling a part of compressed air generated by a compressor of a gas turbine by a TCA cooler (Turbine Cooling Air Cooler), and this turbine cooling air is used. Cooling the hot part of the gas turbine is described. Specifically, in the technique described in Patent Document 1, in the TCA cooler, the compressed air from the compressor of the gas turbine and the high-pressure water supplied to the high-pressure drum of the exhaust heat recovery boiler are subjected to heat exchange, and the compressed air Is cooled to generate turbine cooling air. As a result, not only can turbine cooling air be generated, but the heat of the compressed air can be recovered in the high-pressure feed water that greatly contributes to the generation of steam in the exhaust heat recovery boiler, thereby improving the power generation efficiency of the entire power plant.

特開２０１０−１１２２７４号公報JP 2010-112274 A

ところで、特許文献１のような従来の冷却系統においては、発電プラントの起動時及び低負荷運転時には、排熱回収ボイラにおける高圧給水の蒸発量が少ないため、この少ない蒸発量に応じて、高圧ドラムへの高圧給水の流入量を減らす必要がある。一方、ガスタービンの高温部の冷却を確実に行うためには、ＴＣＡクーラにおける高圧給水の流量をある程度は確保しなければならない。よって、高圧ドラムが要求する高圧給水の流量と、ＴＣＡクーラが要求する高圧給水の流量とが必ずしも一致しない場合が起こり得る。
そこで、ＴＣＡクーラを通過した高圧給水の一部のみを高圧ドラムに導くために、高圧給水の残部を復水器側（復水系）に排出するダンプラインを設けることがある。この場合、高圧給水を高圧ドラムに導く回収ラインおよびダンプラインに、それぞれ、回収弁とダンプ弁を設け、これら二つの弁の開度調節により回収ラインとダンプラインを流れる高圧給水の流量を調節する。これにより、発電プラントの起動時及び低負荷運転時には、回収弁の開度を小さくし、ダンプ弁の開度を大きくすることで、ＴＣＡクーラが要求する高圧給水の流量を維持しながら、少ない蒸発量に見合った適量の高圧給水を高圧ドラムに供給することができる。これに対して、発電プラントの高負荷運転時には、回収弁の開度を大きくし、ダンプ弁の開度を小さくすることで、ＴＣＡクーラが要求する高圧給水の流量を維持しながら、多い蒸発量に見合った適量の高圧給水を高圧ドラムに供給することができる。 By the way, in the conventional cooling system like patent document 1, since the evaporation amount of the high-pressure feed water in a waste heat recovery boiler is small at the time of starting of a power plant and low load operation, according to this small evaporation amount, a high-pressure drum It is necessary to reduce the inflow of high-pressure feedwater to On the other hand, in order to reliably cool the high temperature portion of the gas turbine, the flow rate of the high-pressure feed water in the TCA cooler must be ensured to some extent. Therefore, the flow rate of the high-pressure feed water required by the high-pressure drum may not always match the flow rate of the high-pressure feed water required by the TCA cooler.
Therefore, in order to guide only a part of the high-pressure feed water that has passed through the TCA cooler to the high-pressure drum, a dump line that discharges the remainder of the high-pressure feed water to the condenser side (condensation system) may be provided. In this case, a recovery valve and a dump valve are respectively provided in the recovery line and the dump line that guide the high-pressure feed water to the high-pressure drum, and the flow rate of the high-pressure feed water flowing through the recovery line and the dump line is adjusted by adjusting the opening of these two valves. . This reduces the amount of evaporation while maintaining the flow rate of the high-pressure feed water required by the TCA cooler by reducing the opening of the recovery valve and increasing the opening of the dump valve during startup and low-load operation of the power plant. An appropriate amount of high-pressure water supply corresponding to the amount can be supplied to the high-pressure drum. On the other hand, during high load operation of the power plant, the amount of evaporation is increased while maintaining the flow rate of the high-pressure feed water required by the TCA cooler by increasing the opening of the recovery valve and decreasing the opening of the dump valve. Therefore, an appropriate amount of high-pressure water supply suitable for the pressure can be supplied to the high-pressure drum.

ここで、回収弁とダンプ弁を開度制御する際、回収弁およびダンプ弁の両方について、ＴＣＡクーラを通過する高圧給水の流量に基づくフィードバック制御を行うと、両方の弁が制御干渉を引き起こしてしまう。すなわち、ＴＣＡクーラを通過する高圧給水の流量という１つの制御因子に基づいて、回収弁とダンプ弁という２つの弁を制御することで、各弁の開度制御が互いに干渉し合い、制御上の不都合が生じる。   Here, when controlling the opening of the recovery valve and the dump valve, if feedback control based on the flow rate of high-pressure feed water passing through the TCA cooler is performed for both the recovery valve and the dump valve, both valves cause control interference. End up. That is, by controlling two valves, a recovery valve and a dump valve, based on a single control factor of the flow rate of high-pressure feed water passing through the TCA cooler, the opening control of each valve interferes with each other, Inconvenience arises.

そのため、ＴＣＡクーラを通過する高圧給水の流量に基づくフィードバック制御はダンプ弁のみとし、ガスタービン負荷と回収弁開度との関係を示す関数を用いて、ガスタービンの負荷に対応する開度に回収弁を制御することが考えられる。
ところが、上記関数を用いて回収弁の開度制御を行う場合、ＴＣＡクーラを通過する高圧給水の流量を適切に調節することが難しい。これは、上記関数から求めた開度に回収弁を制御しても、ＴＣＡクーラが設けられたクーラ側給水ラインに対して並列に設けられるＥＣＯ側給水ラインの系統差圧の変化による影響によって、ＴＣＡクーラを通過する高圧給水の所期の流量を確保できるとは限らないためである。なお、ＥＣＯ側給水ラインとは、節炭器が設けられる給水ラインをいう。 Therefore, feedback control based on the flow rate of the high-pressure feed water that passes through the TCA cooler is limited to the dump valve, and is recovered to the opening corresponding to the load of the gas turbine using a function indicating the relationship between the gas turbine load and the recovery valve opening. It is conceivable to control the valve.
However, when the opening degree of the recovery valve is controlled using the above function, it is difficult to appropriately adjust the flow rate of the high-pressure feed water that passes through the TCA cooler. This is because even if the recovery valve is controlled to the opening obtained from the above function, due to the influence of the change in the system differential pressure of the ECO side water supply line provided in parallel to the cooler side water supply line provided with the TCA cooler, This is because the desired flow rate of the high-pressure water supply that passes through the TCA cooler cannot always be secured. In addition, the ECO side water supply line means the water supply line in which a economizer is provided.

本発明は、上述の事情に鑑みてなされたものであり、ダンプ弁と回収弁との相互の制御干渉を防ぐことができ、かつ、クーラを通過する給水の流量を適切に調節しうるコンバインドサイクル発電プラントを提供することを目的とする。   The present invention has been made in view of the above-described circumstances, and can prevent mutual control interference between the dump valve and the recovery valve and can appropriately adjust the flow rate of the feed water passing through the cooler. An object is to provide a power plant.

以下、説明の便宜上、発明を実施するための形態で使用する符号を対応する構成要素に括弧付きで付すが、この符号によって、特許請求の範囲に記載された本発明の技術的範囲の解釈に用いることはできない。   Hereinafter, for convenience of explanation, the reference numerals used in the embodiments for carrying out the invention are attached to the corresponding components in parentheses, but this reference sign interprets the technical scope of the present invention described in the claims. Cannot be used.

本発明に係るコンバインドサイクル発電プラント（１）は、ガスタービン（２）と、前記ガスタービン（２）の排熱を利用して給水を加熱し、蒸気を生成する排熱回収ボイラ（２０）と、前記排熱回収ボイラ（２０）で生成された前記蒸気によって駆動される蒸気タービン（１０）と、前記ガスタービン（２）の高温部の冷却に用いられる冷媒を、前記給水との熱交換によって冷却するクーラ（３１）と、前記クーラ（３１）を通過した後の前記給水の一部を前記排熱回収ボイラ（２０）に戻す回収ライン（３３）と、前記回収ライン（３３）に設けられた回収弁（３７）と、前記クーラ（３１）を通過した後の前記給水の残部を復水系にダンプするダンプライン（３８）と、前記ダンプライン（３８）に設けられたダンプ弁（３９）と、前記回収弁（３７）および前記ダンプ弁（３９）の開度制御を行う弁開度制御手段（５０，６０）とを備え、前記弁開度制御手段（５０，６０）は、前記回収弁（３７）および前記ダンプ弁（３９）のいずれか一方について、該一方の弁の前後差圧に基づく開度制御を行い、前記回収弁（３７）および前記ダンプ弁（３９）の他方について、前記クーラ（３１）を通過する前記給水の流量に基づく開度制御を行うことを特徴とする。
なお、ガスタービン（２）の高温部の冷却に用いられる「冷媒」は、ガスタービン（２）の空気圧縮機（３）で生成される圧縮空気であってもよい。 A combined cycle power plant (1) according to the present invention includes a gas turbine (2), an exhaust heat recovery boiler (20) that heats feed water using exhaust heat of the gas turbine (2), and generates steam. The refrigerant used for cooling the high temperature part of the steam turbine (10) driven by the steam generated in the exhaust heat recovery boiler (20) and the gas turbine (2) is exchanged with the water supply. A cooler (31) for cooling, a recovery line (33) for returning a part of the feed water after passing through the cooler (31) to the exhaust heat recovery boiler (20), and the recovery line (33) are provided. A recovery valve (37), a dump line (38) for dumping the remainder of the water supply after passing through the cooler (31) to a condensate system, and a dump valve (39) provided in the dump line (38) And before And a valve opening degree control means (50, 60) for controlling the opening degree of the recovery valve (37) and the dump valve (39), and the valve opening degree control means (50, 60) includes the recovery valve (37). ) And the dump valve (39), the degree of opening is controlled based on the differential pressure across the one valve, and the other of the recovery valve (37) and the dump valve (39) 31) opening degree control based on the flow rate of the water supply passing through 31) is performed.
The “refrigerant” used for cooling the high temperature part of the gas turbine (2) may be compressed air generated by the air compressor (3) of the gas turbine (2).

このコンバインドサイクル発電プラント（１）によれば、回収弁（３７）およびダンプ弁（３９）のいずれか一方について、該一方の弁の前後差圧に基づく開度制御を行い、回収弁（３７）およびダンプ弁（３９）の他方について、クーラ（３１）を通過する給水流量に基づく開度制御を行うようにしたので、回収弁（３７）とダンプ弁（３９）との相互の制御干渉を防ぐことができる。すなわち、回収弁（３７）およびダンプ弁（３９）のいずれか一方の弁の前後差圧、および、クーラ（３１）を通過する給水流量という２つの制御因子を用い、回収弁（３７）とダンプ弁（３９）とをそれぞれ独立した制御因子によって制御するようにしたので、各弁（３７，３９）の開度制御が互いに干渉し合うことがない。   According to this combined cycle power plant (1), the opening control is performed on one of the recovery valve (37) and the dump valve (39) based on the differential pressure across the one valve, and the recovery valve (37) Since the opening degree control is performed on the other side of the dump valve (39) based on the flow rate of the feed water passing through the cooler (31), mutual interference between the recovery valve (37) and the dump valve (39) is prevented. be able to. That is, the recovery valve (37) and the dump valve are used by using two control factors, the differential pressure across the recovery valve (37) and the dump valve (39) and the feed water flow rate passing through the cooler (31). Since the valves (39) are controlled by independent control factors, the opening control of the valves (37, 39) does not interfere with each other.

上記コンバインドサイクル発電プラント（１）における回収弁（３７）およびダンプ弁（３９）の開度制御は、次の二通りの組み合わせの何れかである。
第一の組み合わせは、回収弁（３７）をその前後差圧に基づいて開度制御し、クーラ（３１）を通過する給水流量に基づいてダンプ弁（３９）を開度制御するものである。この場合、回収弁（３７）の前後差圧を考慮して回収弁（３７）の開度制御を行うため、回収弁（３７）を介して排熱回収ボイラ（２０）に供給される給水流量は所期の流量を確実に確保できる。また、回収弁（３７）を通過する給水流量がクーラ（３１）における給水の必要流量に対して不足していても、ダンプ弁（３９）の開度制御がクーラ（３１）を通過する給水流量に基づくものであるため、ダンプ弁（３９）を通過する給水の流量が適切に調節されて、必要流量の給水をクーラ（３１）に流すことができる。
第二の組み合わせは、第一の組み合わせとは逆に、クーラ（３１）を通過する給水流量に基づいて回収弁（３７）を開度制御し、ダンプ弁（３９）をその前後差圧に基づいて開度制御するものである。この場合、ダンプ弁（３９）の前後差圧を考慮してダンプ弁（３９）の開度制御を行うため、ダンプ弁（３９）を通過する給水流量は所期の流量を確実に確保できる。また、ダンプ弁（３９）を通過する給水流量がクーラ（３１）における給水の必要流量に対して不足していても、回収弁（３７）の開度制御がクーラ（３１）を通過する給水流量に基づくものであるため、回収弁（３７）を通過する給水の流量が適切に調節されて、必要流量の給水をクーラ（３１）に流すことができる。
このように、いずれの組み合わせの場合であっても、回収弁（３７）の開閉制御とダンプ弁（３９）の開閉制御が協働することで、必要流量の給水をクーラ（３１）に流すことができる。 The opening control of the recovery valve (37) and the dump valve (39) in the combined cycle power plant (1) is one of the following two combinations.
In the first combination, the opening degree of the recovery valve (37) is controlled based on the differential pressure across it, and the opening degree of the dump valve (39) is controlled based on the feed water flow rate passing through the cooler (31). In this case, since the opening degree of the recovery valve (37) is controlled in consideration of the differential pressure across the recovery valve (37), the feed water flow rate supplied to the exhaust heat recovery boiler (20) via the recovery valve (37) Can ensure the desired flow rate. Moreover, even if the feed water flow rate that passes through the recovery valve (37) is insufficient with respect to the required flow rate of the feed water in the cooler (31), the opening control of the dump valve (39) passes through the cooler (31). Therefore, the flow rate of the feed water passing through the dump valve (39) is appropriately adjusted, and the feed water of the necessary flow rate can be flowed to the cooler (31).
In contrast to the first combination, the second combination controls the opening of the recovery valve (37) based on the feed water flow rate passing through the cooler (31), and the dump valve (39) based on the differential pressure across the front and rear. To control the opening. In this case, since the opening degree of the dump valve (39) is controlled in consideration of the differential pressure across the dump valve (39), the desired flow rate can be reliably ensured for the feed water flow rate passing through the dump valve (39). Moreover, even if the feed water flow rate passing through the dump valve (39) is insufficient with respect to the required feed water flow rate in the cooler (31), the opening degree control of the recovery valve (37) passes through the cooler (31). Therefore, the flow rate of the feed water that passes through the recovery valve (37) is appropriately adjusted, and the feed water at the required flow rate can be supplied to the cooler (31).
As described above, in any combination, the opening / closing control of the recovery valve (37) and the opening / closing control of the dump valve (39) cooperate to allow the required flow rate of water to flow to the cooler (31). Can do.

上記コンバインドサイクル発電プラント（１）において、前記弁開度制御手段（５０，６０）は、上述の第一の組み合わせによる開度制御を回収弁（３７）およびダンプ弁（３９）について行ってもよい。すなわち、前記弁開度制御手段（５０，６０）は、前記回収弁（３７）の前記前後差圧に基づいて前記回収弁（３７）の開度制御を行うとともに、前記クーラ（３１）を通過する前記給水の前記流量に基づいて前記ダンプ弁（３９）の開度制御を行ってもよい。   In the combined cycle power plant (1), the valve opening control means (50, 60) may perform the opening control by the first combination described above for the recovery valve (37) and the dump valve (39). . That is, the valve opening degree control means (50, 60) controls the opening degree of the recovery valve (37) based on the differential pressure across the recovery valve (37) and passes through the cooler (31). The opening control of the dump valve (39) may be performed based on the flow rate of the water supply.

この場合、前記弁開度制御手段（５０，６０）は、前記回収弁（３７）の前記前後差圧および前記回収弁（３７）を通過する前記給水の流量の指令値からＣｖ値を算出し、該Ｃｖ値に応じた弁開度に前記回収弁（３７）を開度調節してもよい。
ここで、Ｃｖ値とは、バルブの容量係数であり、流体が、ある前後差圧においてバルブを流れるときの流量を表す値である。Ｃｖ値は、一般に、バルブの前後差圧と、バルブを流れる流体の流量との関数であることが知られている。そのため、回収弁（３７）の前後差圧および回収弁（３７）を通過すべき給水流量の指令値からＣｖ値を算出できる。そして、Ｃｖ値に対応する弁開度はバルブ特性として既知であるから、Ｃｖ値の算出結果に応じた弁開度に回収弁（３７）を開度調節することで、回収弁（３７）を通過する給水流量を指令値に維持できる。よって、発電プラント（１）の運転状態（起動時及び低負荷運転時または高負荷運転時）に応じて、回収弁（３７）を介して排熱回収ボイラ（２０）に供給される給水の流量を適切に調節できる。
なお、回収弁（３７）を通過する給水流量の指令値は、排熱回収ボイラ（２０）における給水の蒸発量に応じて決定されてもよい。 In this case, the valve opening degree control means (50, 60) calculates a Cv value from the front-rear differential pressure of the recovery valve (37) and a command value of the flow rate of the feed water passing through the recovery valve (37). The opening degree of the recovery valve (37) may be adjusted to the valve opening degree corresponding to the Cv value.
Here, the Cv value is a capacity coefficient of the valve, and is a value representing a flow rate when the fluid flows through the valve at a certain front-back differential pressure. The Cv value is generally known to be a function of the differential pressure across the valve and the flow rate of the fluid flowing through the valve. Therefore, the Cv value can be calculated from the differential pressure across the recovery valve (37) and the command value of the feed water flow rate that should pass through the recovery valve (37). Since the valve opening corresponding to the Cv value is known as the valve characteristic, the recovery valve (37) is adjusted by adjusting the opening of the recovery valve (37) to the valve opening corresponding to the calculation result of the Cv value. The passing water flow rate can be maintained at the command value. Therefore, the flow rate of the feed water supplied to the exhaust heat recovery boiler (20) via the recovery valve (37) according to the operation state of the power plant (1) (during start-up and low load operation or high load operation). Can be adjusted appropriately.
In addition, the command value of the feed water flow rate that passes through the recovery valve (37) may be determined according to the evaporation amount of the feed water in the exhaust heat recovery boiler (20).

また、上記コンバインドサイクル発電プラント（１）は、前記クーラ（３１）が配置される流路および前記回収ライン（３３）で構成されるクーラ側給水ライン（４２）と、前記クーラ（３１）よりも上流側において前記クーラ側給水ライン（４２）から分岐して、前記回収弁（３７）よりも下流側において前記クーラ側給水ライン（４２）に合流するＥＣＯ側給水ライン（３２）と、前記ＥＣＯ側給水ライン（３２）に設けられた節炭器（２９）と、前記節炭器（２９）の上流側において前記ＥＣＯ側給水ライン（３２）に設けられた制御弁（６２）とをさらに備え、前記制御弁（６２）は、該制御弁（６２）の前後差圧を設定値に維持するように開度制御されてもよい。
このように、クーラ側給水ライン（４２）に対して並列にＥＣＯ側給水ライン（３２）が設けられる場合、例えばガスタービン（２）の負荷遮断時や負荷急減時において、ＥＣＯ側給水ライン（３２）を流れる給水流量が大幅に減少する。そうすると、ＥＣＯ側給水ライン（３２）の系統差圧は、ＥＣＯ側給水ライン（３２）の給水流量の二乗に比例することから、非常に小さくなる。特に、排熱回収ボイラ（２０）のドラム（２３）内の水位を制御するドラムレベル制御弁（６５）がＥＣＯ側給水ライン（３２）ではなく、ドラム（２３）の直前に設けられている場合、ＥＣＯ側給水ライン（３２）の系統差圧はほぼ節炭器（２９）に起因する圧力損失のみであるから、ＥＣＯ側給水ライン（３２）の系統差圧の低下が顕著になる。その結果、相対的にクーラ側給水ライン（４２）に給水が流れにくくなり、回収弁（３７）及びダンプ弁（３９）の開度を全開にしてもクーラ側給水ライン（４２）における給水流量を確保できないことがあり得る。
そこで、上述のように、ＥＣＯ側給水ライン（３２）の節炭器（２９）よりも上流側に制御弁（６２）を設け、該制御弁（６２）の前後差圧を設定値に維持するようにこの制御弁（６２）の開度制御を行うことで、発電プラント（１）の運転状態によらず、ＥＣＯ側給水ライン（３２）の系統差圧を確保できる。よって、回収弁（３７）及びダンプ弁（３９）を全開にしてもクーラ側給水ライン（４２）における給水流量を確保できないような事態を防止できる。 Further, the combined cycle power plant (1) has a cooler-side water supply line (42) composed of a flow path in which the cooler (31) is disposed and the recovery line (33), and the cooler (31). An ECO side water supply line (32) branched from the cooler side water supply line (42) on the upstream side and joined to the cooler side water supply line (42) on the downstream side of the recovery valve (37), and the ECO side A economizer (29) provided in the water supply line (32), and a control valve (62) provided in the ECO-side water supply line (32) on the upstream side of the economizer (29); The opening degree of the control valve (62) may be controlled so as to maintain the differential pressure across the control valve (62) at a set value.
Thus, when the ECO side water supply line (32) is provided in parallel with the cooler side water supply line (42), for example, when the load of the gas turbine (2) is cut off or when the load is suddenly reduced, the ECO side water supply line (32 ) The water supply flow rate flowing through If it does so, since the system | strain differential pressure | voltage of the ECO side water supply line (32) is proportional to the square of the water supply flow volume of the ECO side water supply line (32), it becomes very small. In particular, when the drum level control valve (65) for controlling the water level in the drum (23) of the exhaust heat recovery boiler (20) is provided immediately before the drum (23) instead of the ECO side water supply line (32). Since the system differential pressure of the ECO side water supply line (32) is almost only the pressure loss caused by the economizer (29), the system differential pressure of the ECO side water supply line (32) is significantly reduced. As a result, the water supply becomes relatively less likely to flow into the cooler-side water supply line (42), and the water supply flow rate in the cooler-side water supply line (42) is reduced even when the recovery valve (37) and the dump valve (39) are fully opened. There is a possibility that it cannot be secured.
Therefore, as described above, the control valve (62) is provided on the upstream side of the economizer (29) of the ECO side water supply line (32), and the differential pressure across the control valve (62) is maintained at the set value. Thus, by performing the opening degree control of the control valve (62), the system differential pressure of the ECO side water supply line (32) can be ensured regardless of the operating state of the power plant (1). Therefore, even if the recovery valve (37) and the dump valve (39) are fully opened, it is possible to prevent a situation in which the water supply flow rate in the cooler side water supply line (42) cannot be secured.

本発明によれば、回収弁およびダンプ弁のいずれか一方について、該一方の弁の前後差圧に基づく開度制御を行い、回収弁およびダンプ弁の他方について、クーラを通過する給水流量に基づく開度制御を行うようにしたので、ダンプ弁と回収弁との相互の制御干渉を防ぐことができる。また、回収弁の開閉制御とダンプ弁の開閉制御が協働して、必要流量の給水をクーラに流すことができる。   According to the present invention, the opening degree control based on the differential pressure across the one valve is performed for one of the recovery valve and the dump valve, and the other of the recovery valve and the dump valve is based on the feed water flow rate passing through the cooler. Since the opening degree control is performed, mutual control interference between the dump valve and the recovery valve can be prevented. Further, the opening / closing control of the recovery valve and the opening / closing control of the dump valve cooperate to allow the required amount of water to flow through the cooler.

コンバインドサイクル発電プラントの全体構成を示す図である。It is a figure which shows the whole structure of a combined cycle power plant. 本発明の第１実施形態に係る発電プラントの冷却系統及び弁開度制御装置の構成図である。It is a lineblock diagram of a cooling system of a power plant and a valve opening control device concerning a 1st embodiment of the present invention. 本発明の第２実施形態に係る発電プラントの冷却系統及び弁開度制御装置の構成図である。It is a block diagram of the cooling system and valve opening degree control apparatus of the power plant concerning 2nd Embodiment of this invention.

以下、添付図面に従って本発明の実施形態について説明する。ただし、この実施形態に記載されている構成部品の寸法、材質、形状、その相対的配置等は、特定的な記載がない限り本発明の範囲をこれに限定する趣旨ではなく、単なる説明例にすぎない。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

［第１実施形態］
図１を参照して、本発明の第１実施形態に係るコンバインドサイクル発電プラント（以下、発電プラントと称する）１の構成を説明する。
図１に示すように、発電プラント１は、主に、ガスタービン２と、蒸気タービン１０と、排熱回収ボイラ２０と、冷却系統３０とを備えている。 [First Embodiment]
With reference to FIG. 1, the structure of the combined cycle power plant (henceforth a power plant) 1 which concerns on 1st Embodiment of this invention is demonstrated.
As shown in FIG. 1, the power plant 1 mainly includes a gas turbine 2, a steam turbine 10, an exhaust heat recovery boiler 20, and a cooling system 30.

発電プラント１は、ガスタービン２及び蒸気タービン１０の回転軸が共通である１軸型であってもよいし、ガスタービン２及び蒸気タービン１０の回転軸がそれぞれ独立である多軸型であってもよい。なお、図１には、１軸型の発電プラント１を示した。   The power plant 1 may be a single-shaft type in which the rotation axes of the gas turbine 2 and the steam turbine 10 are common, or a multi-shaft type in which the rotation axes of the gas turbine 2 and the steam turbine 10 are independent from each other. Also good. FIG. 1 shows a uniaxial power plant 1.

ガスタービン２及び蒸気タービン１０の回転軸には、発電機８が連結されている。これにより、ガスタービン２及び蒸気タービン１０の回転軸が回転することで、発電機８が駆動されて電力が生成されるようになっている。   A generator 8 is connected to the rotating shafts of the gas turbine 2 and the steam turbine 10. Thereby, the rotating shaft of the gas turbine 2 and the steam turbine 10 rotates, and the generator 8 is driven to generate electric power.

ガスタービン２は、空気圧縮機３と、タービン４と、燃焼器５とを有している。空気圧縮機３は、大気を吸入して圧縮し、燃焼器５に供給する。燃焼器５では、空気圧縮機３から供給された圧縮空気を燃焼用空気として用い、燃料ガスを燃焼させる。燃焼器５における燃焼によって生成された燃焼ガスは、タービン４に供給され、タービン４を駆動する。タービン４を通過した後の燃焼ガス（排ガス）は、排熱回収ボイラ２０に導かれて、排熱回収ボイラ２０における蒸気生成用熱源として利用された後に排気される。
なお、空気圧縮機３で生成される圧縮空気の一部は、後述する冷却系統３０によって冷却されてタービン冷却空気とされ、タービン４の高温部（例えば動静翼やロータ）の冷却に用いられる。 The gas turbine 2 includes an air compressor 3, a turbine 4, and a combustor 5. The air compressor 3 sucks and compresses the atmosphere and supplies it to the combustor 5. In the combustor 5, the compressed gas supplied from the air compressor 3 is used as combustion air, and fuel gas is combusted. Combustion gas generated by combustion in the combustor 5 is supplied to the turbine 4 to drive the turbine 4. The combustion gas (exhaust gas) after passing through the turbine 4 is guided to the exhaust heat recovery boiler 20 and is exhausted after being used as a heat source for generating steam in the exhaust heat recovery boiler 20.
A part of the compressed air generated by the air compressor 3 is cooled by a cooling system 30 described later to be turbine cooling air, and is used for cooling a high-temperature portion (for example, moving blades and rotors) of the turbine 4.

排熱回収ボイラ２０内には、低圧節炭器２７、中圧節炭器２８、高圧節炭器２９、低圧蒸発器２４、中圧蒸発器２５、及び高圧蒸発器２６が配置されている。低圧蒸発器２４には低圧ドラム２１が付属されている。中圧蒸発器２５には中圧ドラム２２が付属されている。高圧蒸発器２６には高圧ドラム２３が付属されている。   In the exhaust heat recovery boiler 20, a low pressure economizer 27, an intermediate pressure economizer 28, a high pressure economizer 29, a low pressure evaporator 24, an intermediate pressure evaporator 25, and a high pressure evaporator 26 are arranged. A low-pressure drum 21 is attached to the low-pressure evaporator 24. An intermediate pressure drum 22 is attached to the intermediate pressure evaporator 25. A high pressure drum 23 is attached to the high pressure evaporator 26.

蒸気タービン１０は、高圧タービン１１、中圧タービン１２、及び低圧タービン１３を備えている。高圧タービン１１には、高圧ドラム２３からの飽和蒸気を排熱回収ボイラ２０内の高圧過熱器（不図示）で過熱した高圧蒸気が供給される。高圧タービン１１に供給された高圧蒸気は、高圧タービン１１で仕事をした後、排熱回収ボイラ２０内の再熱器（不図示）に送られる。   The steam turbine 10 includes a high-pressure turbine 11, an intermediate-pressure turbine 12, and a low-pressure turbine 13. The high-pressure turbine 11 is supplied with high-pressure steam obtained by overheating the saturated steam from the high-pressure drum 23 by a high-pressure superheater (not shown) in the exhaust heat recovery boiler 20. The high-pressure steam supplied to the high-pressure turbine 11 is sent to a reheater (not shown) in the exhaust heat recovery boiler 20 after working in the high-pressure turbine 11.

排熱回収ボイラ２０の再熱器には、高圧タービン１１で仕事をした後の高圧蒸気（再熱前の低温蒸気）に加えて、中圧ドラム２２からの飽和蒸気を排熱回収ボイラ２０内の中圧過熱器（不図示）で過熱した蒸気も供給される。そして、再熱器で昇温された蒸気は、再熱蒸気として、中圧タービン１２に供給される。中圧タービン１２に供給された再熱蒸気は、中圧タービン１２で仕事をした後、低圧タービン１３に供給される。   In the reheater of the exhaust heat recovery boiler 20, in addition to the high-pressure steam (low-temperature steam before reheating) after working in the high-pressure turbine 11, saturated steam from the intermediate pressure drum 22 is contained in the exhaust heat recovery boiler 20. Steam heated by a medium pressure superheater (not shown) is also supplied. The steam heated by the reheater is supplied to the intermediate pressure turbine 12 as reheated steam. The reheat steam supplied to the intermediate pressure turbine 12 is supplied to the low pressure turbine 13 after working in the intermediate pressure turbine 12.

低圧タービン１３には、中圧タービン１２で仕事をした後の再熱蒸気に加えて、低圧ドラム２１からの飽和蒸気を排熱回収ボイラ２０内の低圧過熱器（不図示）で過熱した蒸気も供給される。   In addition to the reheated steam after working in the intermediate pressure turbine 12, the low pressure turbine 13 also includes steam obtained by superheating saturated steam from the low pressure drum 21 by a low pressure superheater (not shown) in the exhaust heat recovery boiler 20. Supplied.

低圧タービン１３からの排気は、復水器１５に導かれ、復水される。復水器１５で生成された水は、低圧給水ポンプ１６により、低圧節炭器２７に導入される。低圧節炭器２７を通過した水は、一部が低圧ドラム２１に給水され、残りは高中圧給水ポンプ１７に導かれる。高中圧給水ポンプ１７は、高圧給水ポンプ４０（図２、図３参照）と中圧給水ポンプとを有している。高圧給水ポンプ４０は、高圧節炭器２９を介して、高圧給水を高圧ドラム２３に供給する。また、中圧給水ポンプは、中圧節炭器２８を介して、中圧水を中圧ドラム２２に給水する。高圧ドラム２３、中圧ドラム２２、及び低圧ドラム２１へ供給された水は、それぞれ、高圧蒸発器２６、低圧蒸発器２４、及び中圧蒸発器２５においてタービン４からの排ガスと熱交換されて蒸発し、各ドラム（２３，２２，２１）に飽和蒸気として溜まるようになっている。   Exhaust gas from the low-pressure turbine 13 is guided to the condenser 15 to be condensed. The water generated in the condenser 15 is introduced into the low pressure economizer 27 by the low pressure feed water pump 16. Part of the water that has passed through the low-pressure economizer 27 is supplied to the low-pressure drum 21, and the rest is guided to the high / medium-pressure water supply pump 17. The high / medium pressure feed water pump 17 has a high pressure feed water pump 40 (see FIGS. 2 and 3) and an intermediate pressure feed water pump. The high-pressure water supply pump 40 supplies high-pressure water supply to the high-pressure drum 23 via the high-pressure economizer 29. Further, the intermediate pressure water supply pump supplies intermediate pressure water to the intermediate pressure drum 22 via the intermediate pressure economizer 28. The water supplied to the high-pressure drum 23, the medium-pressure drum 22, and the low-pressure drum 21 is evaporated by exchanging heat with the exhaust gas from the turbine 4 in the high-pressure evaporator 26, the low-pressure evaporator 24, and the medium-pressure evaporator 25, respectively. In addition, each drum (23, 22, 21) accumulates as saturated steam.

さらに本実施形態に係る発電プラント１は、空気圧縮機３からの圧縮空気の一部を冷却してタービン冷却空気とする冷却系統３０を備えている。図２を用いて、冷却系統３０の構成について説明する。
同図に示すように、冷却系統３０は、高圧給水ポンプ４０と高圧ドラム２３との間において、クーラ側給水ライン４２とＥＣＯ側給水ライン３２とを有している。ＥＣＯ側給水ライン３２は、後述するＴＣＡクーラ３１の上流側の分岐点Ａにおいてクーラ側給水ライン４２から分岐し、後述する回収弁３７よりも下流側の合流点Ｂにおいてクーラ側給水ライン４２と合流する。
なお、ＥＣＯ側給水ライン３２には、排熱回収ボイラ２０の高圧節炭器２９が設けられている。またＥＣＯ側給水ライン３２には、高圧ドラム２３の水位を制御するためのドラム制御弁を設けてもよい。 Furthermore, the power plant 1 according to the present embodiment includes a cooling system 30 that cools a part of the compressed air from the air compressor 3 to form turbine cooling air. The configuration of the cooling system 30 will be described with reference to FIG.
As shown in the figure, the cooling system 30 includes a cooler-side water supply line 42 and an ECO-side water supply line 32 between the high-pressure water supply pump 40 and the high-pressure drum 23. The ECO side water supply line 32 branches from the cooler side water supply line 42 at a branch point A upstream of the TCA cooler 31 described later, and joins the cooler side water supply line 42 at a junction B downstream of the recovery valve 37 described later. To do.
The ECO-side water supply line 32 is provided with a high-pressure economizer 29 for the exhaust heat recovery boiler 20. The ECO-side water supply line 32 may be provided with a drum control valve for controlling the water level of the high-pressure drum 23.

クーラ側給水ライン４２には、空気圧縮機３からの圧縮空気の一部を冷却するＴＣＡクーラ３１が設けられている。ＴＣＡクーラ３１では、空気圧縮機３からの圧縮空気の一部が、ＴＣＡクーラ３１内を流れる高圧給水との熱交換によって冷却されるようになっている。ＴＣＡクーラ３１で冷却された圧縮空気は、タービン冷却空気として、タービン４の高温部の冷却に用いられる。   The cooler-side water supply line 42 is provided with a TCA cooler 31 that cools a part of the compressed air from the air compressor 3. In the TCA cooler 31, a part of the compressed air from the air compressor 3 is cooled by heat exchange with high-pressure feed water flowing in the TCA cooler 31. The compressed air cooled by the TCA cooler 31 is used for cooling the high temperature portion of the turbine 4 as turbine cooling air.

クーラ側給水ライン４２のＴＣＡクーラ３１よりも下流側には、ＥＣＯ側給水ライン３２との合流点Ｂに向かって回収ライン３３が延びている。この回収ライン３３は、ＴＣＡクーラ３１を通過した後の高圧給水を回収して、高圧ドラム２３に送るための配管である。なお、回収ライン３３には、回収ライン３３を流れる高圧給水の流量を調節するための回収弁３７が設けられている。   A recovery line 33 extends toward the junction B with the ECO side water supply line 32 on the downstream side of the TCA cooler 31 of the cooler side water supply line 42. The recovery line 33 is a pipe for recovering the high-pressure feed water after passing through the TCA cooler 31 and sending it to the high-pressure drum 23. The recovery line 33 is provided with a recovery valve 37 for adjusting the flow rate of the high-pressure feed water flowing through the recovery line 33.

また、ＴＣＡクーラ３１の下流側には、回収ライン３３とは別に、ＴＣＡクーラ３１を通過した後の高圧給水を復水系にダンプ（排出）するダンプライン３８が設けられている。このダンプライン３８には、ダンプライン３８を流れる高圧給水の流量を調節するためのダンプ弁３９が設けられている。   In addition to the recovery line 33, a dump line 38 that dumps (discharges) the high-pressure feed water that has passed through the TCA cooler 31 to the condensate system is provided on the downstream side of the TCA cooler 31. The dump line 38 is provided with a dump valve 39 for adjusting the flow rate of the high-pressure feed water flowing through the dump line 38.

本実施形態では、回収ライン３３の回収弁３７とダンプライン３８のダンプ弁３９は、弁開度制御装置５０によって開度制御される。具体的には、弁開度制御装置５０は、回収弁３７をその前後差圧に基づいて開度制御し、ＴＣＡクーラ３１を流れる高圧給水の流量に基づいてダンプ弁３９の開度制御を行う。
なお、回収弁３７の前後差圧は、回収弁３７の入口側に配置された第１圧力センサ３４の計測値と、回収弁３７の出口側に配置された第２圧力センサ３５の計測値との差分から求めてもよい。あるいは、回収弁３７の前後に設置した差圧計（不図示）によって、回収弁３７の前後差圧を取得してもよい。
また、ＴＣＡクーラ３１を流れる高圧給水の流量は、ＴＣＡクーラ３１の上流側に設けた流量計３６の計測値から求めてもよい。 In the present embodiment, the opening degree of the recovery valve 37 of the recovery line 33 and the dump valve 39 of the dump line 38 are controlled by the valve opening degree control device 50. Specifically, the valve opening degree control device 50 controls the opening degree of the dump valve 39 based on the flow rate of the high-pressure feed water flowing through the TCA cooler 31 by controlling the opening degree of the recovery valve 37 based on the differential pressure across it. .
Note that the differential pressure across the recovery valve 37 is a measured value of the first pressure sensor 34 disposed on the inlet side of the recovery valve 37 and a measured value of the second pressure sensor 35 disposed on the outlet side of the recovery valve 37. You may obtain | require from the difference of. Alternatively, the differential pressure across the recovery valve 37 may be acquired by a differential pressure gauge (not shown) installed before and after the recovery valve 37.
Further, the flow rate of the high-pressure feed water flowing through the TCA cooler 31 may be obtained from the measured value of the flow meter 36 provided on the upstream side of the TCA cooler 31.

弁開度制御装置５０は、上述のように、回収弁３７の前後差圧に基づいて、回収弁３７を開度制御する。このとき、回収弁３７の前後差圧および回収弁３７を通過すべき高圧給水の流量指令値からＣｖ値を算出し、該Ｃｖ値に応じた弁開度に回収弁３７を開度調節してもよい。すなわち、回収弁３７の開度は、Ｃｖ値に基づく先行開度制御によって調節されてもよい。
ここで、Ｃｖ値とは、バルブの容量係数であり、流体が、ある前後差圧においてバルブを流れるときの流量を表す値である。Ｃｖ値は、一般に、バルブの前後差圧と、バルブを流れる流体の流量との関数であることが知られている。そのため、この関数を用いれば、回収弁３７の前後差圧および回収弁３７を通過する高圧給水流量の指令値からＣｖ値を算出できる。そして、Ｃｖ値に対応する弁開度はバルブ特性として既知であるから、Ｃｖ値の算出結果に応じた弁開度に回収弁３７を開度調節することで、回収弁３７を通過する給水流量を指令値に維持できる。なお、回収弁３７を通過する高圧給水流量の指令値は、高圧ドラム２３における蒸発量に応じて決定されてもよい。
これにより、発電プラント１の運転状態（起動時及び低負荷運転時または高負荷運転時）に応じて、回収弁３７を介して排熱回収ボイラ２０の高圧ドラム２３に供給される給水の流量を適切に調節できる。 The valve opening degree control device 50 controls the opening degree of the recovery valve 37 based on the differential pressure across the recovery valve 37 as described above. At this time, the Cv value is calculated from the differential pressure across the recovery valve 37 and the flow rate command value of the high-pressure feed water that should pass through the recovery valve 37, and the recovery valve 37 is adjusted to an opening corresponding to the Cv value. Also good. That is, the opening degree of the recovery valve 37 may be adjusted by preceding opening degree control based on the Cv value.
Here, the Cv value is a capacity coefficient of the valve, and is a value representing a flow rate when the fluid flows through the valve at a certain front-back differential pressure. The Cv value is generally known to be a function of the differential pressure across the valve and the flow rate of the fluid flowing through the valve. Therefore, by using this function, the Cv value can be calculated from the command value of the differential pressure across the recovery valve 37 and the high-pressure feed water flow rate passing through the recovery valve 37. Since the valve opening corresponding to the Cv value is known as the valve characteristic, the feed water flow rate passing through the recovery valve 37 is adjusted by adjusting the opening of the recovery valve 37 to the valve opening corresponding to the calculation result of the Cv value. Can be maintained at the command value. Note that the command value of the high-pressure feed water flow rate that passes through the recovery valve 37 may be determined according to the evaporation amount in the high-pressure drum 23.
Thereby, the flow rate of the feed water supplied to the high-pressure drum 23 of the exhaust heat recovery boiler 20 via the recovery valve 37 according to the operation state of the power plant 1 (at start-up and low-load operation or high-load operation). It can be adjusted appropriately.

また弁開度制御装置５０は、上述のように、ＴＣＡクーラ３１を通過する高圧給水の流量に基づいてダンプ弁３９を開度制御する。このとき、ダンプ弁３９の開度は、ＴＣＡクーラ３１における高圧給水流量を目標流量に維持するようなフィードバック制御により調節してもよい。例えば、流量計３６の計測値と、ＴＣＡクーラ３１における高圧給水の目標流量との偏差に応じて、ダンプ弁３９の開度をＰＩ制御によって調節してもよい。
なお、ＴＣＡクーラ３１における高圧給水の目標流量は、タービン４の高温部を冷却するのに必要なタービン冷却空気の量及び温度から決定されてもよい。 Moreover, the valve opening degree control apparatus 50 controls the opening degree of the dump valve 39 based on the flow rate of the high-pressure feed water that passes through the TCA cooler 31 as described above. At this time, the opening degree of the dump valve 39 may be adjusted by feedback control that maintains the high-pressure feed water flow rate in the TCA cooler 31 at the target flow rate. For example, the opening degree of the dump valve 39 may be adjusted by PI control according to the deviation between the measured value of the flow meter 36 and the target flow rate of the high-pressure water supply in the TCA cooler 31.
Note that the target flow rate of the high-pressure feed water in the TCA cooler 31 may be determined from the amount and temperature of turbine cooling air necessary for cooling the high temperature portion of the turbine 4.

以上説明したように、本実施形態では、回収弁３７についてその前後差圧に基づく開度制御を行い、ダンプ弁３９についてＴＣＡクーラ３１における高圧給水流量に基づく開度制御を行うようにしたので、回収弁３７とダンプ弁３９との相互の制御干渉を防ぐことができる。すなわち、回収弁３７の前後差圧と、ＴＣＡクーラ３１における高圧給水流量という２つの制御因子を用い、回収弁３７とダンプ弁３９とをそれぞれ独立した制御因子によって制御するようにしたので、各弁（３７，３９）の開度制御が互いに干渉し合うことがない。   As described above, in the present embodiment, the opening control based on the differential pressure across the recovery valve 37 is performed, and the opening control based on the high-pressure feed water flow rate in the TCA cooler 31 is performed on the dump valve 39. Mutual control interference between the recovery valve 37 and the dump valve 39 can be prevented. That is, since the two control factors of the differential pressure across the recovery valve 37 and the high-pressure feed water flow rate in the TCA cooler 31 are used, the recovery valve 37 and the dump valve 39 are controlled by independent control factors. The opening control of (37, 39) does not interfere with each other.

また、本実施形態では、回収弁３７の前後差圧を考慮して回収弁３７の開度制御を行うため、回収弁３７を介して排熱回収ボイラ２０の高圧ドラム２３に供給される高圧給水流量は所期の流量を確実に確保できる。また、回収弁３７を通過する高圧給水流量がＴＣＡクーラ３１における高圧給水の必要流量に対して不足していても、ダンプ弁３９の開度制御がＴＣＡクーラ３１を通過する高圧給水流量に基づくものであるため、ダンプ弁３９を通過する高圧給水の流量が適切に調節されて、必要流量の高圧給水をＴＣＡクーラ３１に流すことができる。
このように、回収弁３７の開閉制御とダンプ弁３９の開閉制御が協働することで、必要流量の高圧給水をＴＣＡクーラ３１に流すことができる。 In the present embodiment, since the opening degree of the recovery valve 37 is controlled in consideration of the differential pressure across the recovery valve 37, the high-pressure water supply supplied to the high-pressure drum 23 of the exhaust heat recovery boiler 20 via the recovery valve 37. The desired flow rate can be reliably secured. Further, even if the high-pressure feed water flow rate that passes through the recovery valve 37 is insufficient with respect to the required flow rate of high-pressure feed water in the TCA cooler 31, the opening control of the dump valve 39 is based on the high-pressure feed water flow rate that passes through the TCA cooler 31. Therefore, the flow rate of the high-pressure feed water that passes through the dump valve 39 is appropriately adjusted, and the high-pressure feed water at the required flow rate can be supplied to the TCA cooler 31.
In this way, the opening / closing control of the recovery valve 37 and the opening / closing control of the dump valve 39 cooperate to allow a high-pressure water supply with a required flow rate to flow through the TCA cooler 31.

なお、本実施形態では、回収弁３７についてその前後差圧に基づく開度制御を行い、ダンプ弁３９についてＴＣＡクーラ３１における高圧給水流量に基づく開度制御を行う例について説明した。しかし、本実施形態とは逆に、弁開度制御装置５０は、ダンプ弁３９についてその前後差圧に基づく開度制御を行い、回収弁３７についてＴＣＡクーラ３１における高圧給水流量に基づく開度制御を行ってもよい。
この場合、ダンプ弁３９の前後差圧の計測値およびダンプ弁３９を通過する高圧給水の流量の指令値からＣｖ値を算出し、該Ｃｖ値に応じた弁開度にダンプ弁３９を開度調節してもよい。すなわち、ダンプ弁３９の開度は、Ｃｖ値に基づく先行開度制御によって調節されてもよい。なお、ダンプ弁３９を通過する高圧給水流量の指令値は、ＴＣＡクーラ３１が必要とする高圧給水流量と、回収弁３７を通過すべき高圧給水流量の目標値との差分から求めてもよい。
また、回収弁３７の開度は、ＴＣＡクーラ３１における高圧給水流量を指令値に維持するようなフィードバック制御により調節してもよい。例えば、流量計３６の計測値と、ＴＣＡクーラ３１における高圧給水の目標流量との偏差に応じて、回収弁３７の開度をＰＩ制御によって調節してもよい。 In the present embodiment, the example in which the opening degree control is performed on the recovery valve 37 based on the differential pressure before and after the recovery valve 37 and the opening degree control is performed on the dump valve 39 based on the high-pressure feed water flow rate in the TCA cooler 31 has been described. However, contrary to the present embodiment, the valve opening degree control device 50 performs opening degree control on the dump valve 39 based on the differential pressure before and after it, and the opening degree control on the recovery valve 37 based on the high-pressure feed water flow rate in the TCA cooler 31. May be performed.
In this case, the Cv value is calculated from the measured value of the differential pressure across the dump valve 39 and the command value of the flow rate of the high-pressure feed water passing through the dump valve 39, and the dump valve 39 is opened to a valve opening corresponding to the Cv value. You may adjust. That is, the opening degree of the dump valve 39 may be adjusted by preceding opening degree control based on the Cv value. The command value of the high-pressure feed water flow that passes through the dump valve 39 may be obtained from the difference between the high-pressure feed water flow required by the TCA cooler 31 and the target value of the high-pressure feed water flow that should pass through the recovery valve 37.
The opening degree of the recovery valve 37 may be adjusted by feedback control that maintains the high-pressure feed water flow rate in the TCA cooler 31 at the command value. For example, the opening degree of the recovery valve 37 may be adjusted by PI control according to the deviation between the measured value of the flow meter 36 and the target flow rate of the high-pressure water supply in the TCA cooler 31.

［第２実施形態］
次に、第２実施形態に係る発電プラントについて説明する。本実施形態の発電プラントは、冷却系統の構成と弁開度制御装置の制御内容を除けば、第１実施形態のコンバインドサイクル発電プラント１と同様である。そのため、ここでは、第１実施形態と共通する箇所には同一の符号を付してその説明を省略し、第１実施形態と異なる部分を中心に説明する。 [Second Embodiment]
Next, a power plant according to the second embodiment will be described. The power plant of the present embodiment is the same as the combined cycle power plant 1 of the first embodiment, except for the configuration of the cooling system and the control content of the valve opening control device. Therefore, here, the same reference numerals are given to the same portions as those in the first embodiment, and the description thereof will be omitted, and the description will focus on the parts different from the first embodiment.

図３は、本実施形態における冷却系統および弁開度制御装置の構成例を示す図である。
同図に示すように、本実施形態における冷却系統７０では、ＥＣＯ側給水ライン３２の高圧節炭器２９の上流側に制御弁６２を設けている。この制御弁６２は、弁開度制御装置６０によって、制御弁６２の前後差圧を設定値に維持するように開度制御されている。具体的には、差圧計６１によって取得した制御弁６２の前後差圧が設定値になるように、制御弁６２の開度制御を行う。
このように、本実施形態において、ＥＣＯ側給水ライン３２に制御弁６２を設け、該制御弁６２の前後差圧を設定値に維持するようにこの制御弁６２の開度制御を行うのは、次の理由による。 FIG. 3 is a diagram illustrating a configuration example of the cooling system and the valve opening degree control device in the present embodiment.
As shown in the figure, in the cooling system 70 in this embodiment, a control valve 62 is provided on the upstream side of the high-pressure economizer 29 in the ECO-side water supply line 32. The opening degree of the control valve 62 is controlled by the valve opening degree control device 60 so as to maintain the differential pressure across the control valve 62 at a set value. Specifically, the opening degree of the control valve 62 is controlled so that the differential pressure across the control valve 62 acquired by the differential pressure gauge 61 becomes a set value.
Thus, in this embodiment, the control valve 62 is provided in the ECO side water supply line 32, and the opening degree control of the control valve 62 is performed so as to maintain the differential pressure across the control valve 62 at a set value. For the following reason.

クーラ側給水ライン４２に対して並列にＥＣＯ側給水ライン３２が設けられる場合、例えばガスタービン２の負荷遮断時や負荷急減時において、ＥＣＯ側給水ライン３２を流れる高圧給水の流量が大幅に減少する。そうすると、ＥＣＯ側給水ライン３２の系統差圧（分岐点Ａと合流点Ｂとの間のＥＣＯ側給水ライン３２の圧力損失）は、ＥＣＯ側給水ライン３２の高圧給水流量の二乗に比例することから、非常に小さくなる。特に、排熱回収ボイラ２０の高圧ドラム２３内の水位を制御するドラムレベル制御弁６５が、図３に示すように、ＥＣＯ側給水ライン３２（分岐点Ａと合流点Ｂとの間）ではなく、高圧ドラム２３の直前に設けられている場合、ＥＣＯ側給水ライン３２の系統差圧は高圧節炭器２９に起因する圧力損失のみであるから、ＥＣＯ側給水ライン３２の系統差圧の低下が顕著になる。その結果、相対的にクーラ側給水ライン４２に高圧給水が流れにくくなり、回収弁３７及びダンプ弁３９の開度を全開にしてもクーラ側給水ライン４２における高圧給水流量を確保できないことがあり得る。
そこで、本実施形態のように、ＥＣＯ側給水ライン３２の高圧節炭器２９よりも上流側に制御弁６２を設け、該制御弁６２の前後差圧を設定値に維持するようにこの制御弁６２の開度制御を行うことで、発電プラントの運転状態によらず、ＥＣＯ側給水ライン３２の系統差圧を確保できる。よって、回収弁３７及びダンプ弁３９を全開にしても回収ライン３３における高圧給水流量を確保できないような事態を防止できる。 When the ECO-side water supply line 32 is provided in parallel to the cooler-side water supply line 42, for example, when the load of the gas turbine 2 is interrupted or when the load is suddenly reduced, the flow rate of the high-pressure water supply flowing through the ECO-side water supply line 32 is greatly reduced. . Then, the system differential pressure of the ECO side water supply line 32 (pressure loss of the ECO side water supply line 32 between the branch point A and the junction B) is proportional to the square of the high pressure water supply flow rate of the ECO side water supply line 32. , Very small. In particular, the drum level control valve 65 for controlling the water level in the high pressure drum 23 of the exhaust heat recovery boiler 20 is not the ECO side water supply line 32 (between the branch point A and the junction B) as shown in FIG. In the case where it is provided immediately before the high-pressure drum 23, the system differential pressure of the ECO side water supply line 32 is only the pressure loss caused by the high pressure economizer 29. Become prominent. As a result, it is relatively difficult for high-pressure water supply to flow into the cooler-side water supply line 42, and even if the recovery valve 37 and the dump valve 39 are fully opened, the high-pressure water supply flow rate in the cooler-side water supply line 42 may not be ensured. .
Therefore, as in this embodiment, a control valve 62 is provided upstream of the high-pressure economizer 29 in the ECO-side water supply line 32, and this control valve 62 is maintained so that the differential pressure across the control valve 62 is maintained at a set value. By performing the opening degree control of 62, the system differential pressure of the ECO side water supply line 32 can be ensured regardless of the operating state of the power plant. Therefore, even if the recovery valve 37 and the dump valve 39 are fully opened, it is possible to prevent a situation in which the high-pressure feed water flow rate in the recovery line 33 cannot be secured.

また、本実施形態において、弁開度制御装置６０による回収弁３７及びダンプ弁３９の開度制御は、上述の第１実施形態における弁開度制御装置５０による開度制御と同様である。
すなわち、弁開度制御装置６０は、回収弁３７についてその前後差圧に基づく開度制御を行い、ダンプ弁３９についてＴＣＡクーラ３１における高圧給水流量に基づく開度制御を行ってもよい。あるいは、弁開度制御装置６０は、ダンプ弁３９についてその前後差圧に基づく開度制御を行い、回収弁３７についてＴＣＡクーラ３１における高圧給水流量に基づく開度制御を行ってもよい。 In the present embodiment, the opening control of the recovery valve 37 and the dump valve 39 by the valve opening control device 60 is the same as the opening control by the valve opening control device 50 in the first embodiment described above.
That is, the valve opening control device 60 may perform opening control based on the differential pressure across the recovery valve 37 and perform opening control based on the high-pressure feed water flow rate in the TCA cooler 31 for the dump valve 39. Alternatively, the valve opening control device 60 may perform opening control based on the differential pressure across the dump valve 39 and perform opening control based on the high-pressure feed water flow rate in the TCA cooler 31 for the recovery valve 37.

以上、本発明の実施形態について詳細に説明したが、本発明はこれに限定されず、本発明の要旨を逸脱しない範囲において、上述の第１実施形態及び第２実施形態を適宜組み合わせてもよいし、各種の改良や変形を行ってもよいのはいうまでもない。   As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to this, You may combine the above-mentioned 1st Embodiment and 2nd Embodiment suitably in the range which does not deviate from the summary of this invention. However, it goes without saying that various improvements and modifications may be made.

例えば、上述の実施形態では、空気圧縮機３からの圧縮空気の一部をＴＣＡクーラ３１で冷却してタービン冷却空気とし、このタービン冷却空気によってガスタービン２の高温部を冷却する例について説明したが、ガスタービン２の高温部の冷却は任意の冷媒を用いてもよい。
また、上述の実施形態では、高圧給水ポンプ４０から吐出される高圧給水をクーラ（ＴＣＡクーラ３１）に供給する例について説明したが、排熱回収ボイラ２０に供給される任意の給水（中圧水や低圧水）をクーラに導いて、ガスタービン２の高温部を冷却するための冷媒を生成するために用いてもよい。 For example, in the above-described embodiment, an example in which a part of the compressed air from the air compressor 3 is cooled by the TCA cooler 31 to be turbine cooling air, and the high temperature portion of the gas turbine 2 is cooled by the turbine cooling air has been described. However, any cooling medium may be used for cooling the high temperature portion of the gas turbine 2.
Moreover, although the above-mentioned embodiment demonstrated the example which supplies the high pressure feed water discharged from the high pressure feed water pump 40 to a cooler (TCA cooler 31), arbitrary feed water (medium pressure water) supplied to the waste heat recovery boiler 20 is described. Or low pressure water) may be guided to the cooler and used to generate a refrigerant for cooling the high temperature portion of the gas turbine 2.

１ コンバインドサイクル発電プラント
２ ガスタービン
３ 空気圧縮機
４ タービン
５ 燃焼器
８ 発電機
１０ 蒸気タービン
１１ 高圧タービン
１２ 中圧タービン
１３ 低圧タービン
２０ 排熱回収ボイラ
２１ 低圧ドラム
２２ 中圧ドラム
２３ 高圧ドラム
２４ 低圧蒸発器
２５ 中圧蒸発器
２６ 高圧蒸発器
２７ 低圧節炭器
２８ 中圧節炭器
２９ 高圧節炭器
３０ 冷却系統
３１ ＴＣＡクーラ（クーラ）
３２ ＥＣＯ側給水ライン
３３ 回収ライン
３４ 第１圧力センサ
３５ 第２圧力センサ
３６ 流量計
３７ 回収弁
３８ ダンプライン
３９ ダンプ弁
４０ 高圧給水ポンプ
４２ クーラ側給水ライン
５０ 弁開度制御装置（弁開度制御手段）
６０ 弁開度制御装置（弁開度制御手段）
６１ 差圧計
６２ 制御弁
６５ ドラムレベル制御弁

DESCRIPTION OF SYMBOLS 1 Combined cycle power plant 2 Gas turbine 3 Air compressor 4 Turbine 5 Combustor 8 Generator 10 Steam turbine 11 High pressure turbine 12 Medium pressure turbine 13 Low pressure turbine 20 Waste heat recovery boiler 21 Low pressure drum 22 Medium pressure drum 23 High pressure drum 24 Low pressure Evaporator 25 Medium pressure evaporator 26 High pressure evaporator 27 Low pressure economizer 28 Medium pressure economizer 29 High pressure economizer 30 Cooling system 31 TCA cooler (cooler)
32 ECO side water supply line 33 Recovery line 34 First pressure sensor 35 Second pressure sensor 36 Flow meter 37 Recovery valve 38 Dump line 39 Dump valve 40 High pressure water supply pump 42 Cooler side water supply line 50 Valve opening degree control device (valve opening degree control) means)
60 Valve opening control device (valve opening control means)
61 Differential pressure gauge 62 Control valve 65 Drum level control valve

Claims (4)

ガスタービンと、
前記ガスタービンの排熱を利用して給水を加熱し、蒸気を生成する排熱回収ボイラと、
前記排熱回収ボイラで生成された前記蒸気によって駆動される蒸気タービンと、
前記ガスタービンの高温部の冷却に用いられる冷媒を、前記給水との熱交換によって冷却するクーラと、
前記クーラを通過した後の前記給水の一部を前記排熱回収ボイラに戻す回収ラインと、
前記回収ラインに設けられた回収弁と、
前記クーラを通過した後の前記給水の残部を復水系にダンプするダンプラインと、
前記ダンプラインに設けられたダンプ弁と、
前記回収弁および前記ダンプ弁の開度制御を行う弁開度制御手段とを備え、
前記弁開度制御手段は、
前記回収弁および前記ダンプ弁のいずれか一方について、該一方の弁の前後差圧に基づく開度制御を行い、
前記回収弁および前記ダンプ弁の他方について、前記クーラを通過する前記給水の流量に基づく開度制御を行うことを特徴とするコンバインドサイクル発電プラント。 A gas turbine,
An exhaust heat recovery boiler that heats feed water using the exhaust heat of the gas turbine and generates steam;
A steam turbine driven by the steam generated in the exhaust heat recovery boiler;
A cooler that cools the refrigerant used for cooling the high-temperature portion of the gas turbine by heat exchange with the feed water;
A recovery line for returning a part of the water supply after passing through the cooler to the exhaust heat recovery boiler;
A recovery valve provided in the recovery line;
A dump line for dumping the remainder of the water supply after passing through the cooler to a condensate system;
A dump valve provided in the dump line;
A valve opening control means for controlling the opening of the recovery valve and the dump valve;
The valve opening control means is
For any one of the recovery valve and the dump valve, opening control based on the differential pressure across the one valve is performed,
The combined cycle power plant, wherein the opening of the other of the recovery valve and the dump valve is controlled based on the flow rate of the feed water passing through the cooler. 前記弁開度制御手段は、前記回収弁の前記前後差圧に基づいて前記回収弁の開度制御を行うとともに、前記クーラを通過する前記給水の前記流量に基づいて前記ダンプ弁の開度制御を行うことを特徴とする請求項１に記載のコンバインドサイクル発電プラント。   The valve opening control means controls the opening of the recovery valve based on the differential pressure across the recovery valve, and controls the opening of the dump valve based on the flow rate of the feed water passing through the cooler. The combined cycle power plant according to claim 1, wherein: 前記弁開度制御手段は、前記回収弁の前記前後差圧および前記回収弁を通過する前記給水の流量の指令値からＣｖ値を算出し、該Ｃｖ値に応じた弁開度に前記回収弁を開度調節することを特徴とする請求項２に記載のコンバインドサイクル発電プラント。   The valve opening degree control means calculates a Cv value from the differential pressure across the recovery valve and a command value of the flow rate of the feed water passing through the recovery valve, and sets the recovery valve to a valve opening degree corresponding to the Cv value. The combined cycle power plant according to claim 2, wherein the opening is adjusted. 前記クーラが配置される流路および前記回収ラインで構成されるクーラ側給水ラインと、
前記クーラよりも上流側において前記クーラ側給水ラインから分岐して、前記回収弁よりも下流側において前記クーラ側給水ラインに合流するＥＣＯ側給水ラインと、
前記ＥＣＯ側給水ラインに設けられた節炭器と、
前記節炭器の上流側において前記ＥＣＯ側給水ラインに設けられた制御弁とをさらに備え、
前記制御弁は、該制御弁の前後差圧を設定値に維持するように開度制御されることを特徴とする請求項１乃至３のいずれか一項に記載のコンバインドサイクル発電プラント。
A cooler-side water supply line composed of a flow path in which the cooler is disposed and the recovery line;
An ECO-side water supply line that branches from the cooler-side water supply line upstream of the cooler and merges with the cooler-side water supply line downstream of the recovery valve;
A economizer provided in the ECO side water supply line;
A control valve provided in the ECO side water supply line on the upstream side of the economizer;
4. The combined cycle power plant according to claim 1, wherein the opening degree of the control valve is controlled so as to maintain a differential pressure across the control valve at a set value. 5.
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