Combined cycle power plant with auxiliary air-cooled condenser
View Patent ↗A combined cycle power plant ( 20 ) including a main air-cooled condenser ( 22 ) condensing steam at a first pressure and an auxiliary air-cooled condenser ( 24 ) condensing steam at a second pressure higher than the first pressure. Designing an air-cooled combined cycle power plant for startup on a hot day can significantly increase the size and cost of the required air-cooled condenser. Adding an auxiliary air-cooled condenser having appropriate thermal characteristics relative to a main air cooled compressor to the steam bypass circuit of an air-cooled combined cycle power plant enables the plant to meet plant startup requirements during periods of peak thermal load in a more cost effective manner than would be achievable with the main air cooled condenser alone.
1. A condenser apparatus for a combined cycle power plant, said apparatus comprising:
a main air-cooled condenser configured to condense steam at a first operating pressure; and
a steam bypass circuit for selectively bypassing steam around a steam turbine of the power plant, the bypass circuit having an auxiliary air-cooled condenser for passing the steam that bypasses the steam turbine, the auxiliary air-cooled condenser coupled to the main air-cooled condenser, said auxiliary condenser configured to condense steam at a second operating pressure higher than said first operating pressure.
2. The condenser apparatus of claim 1 wherein said auxiliary condenser is coupled in parallel flow to said main condenser.
3. The condenser apparatus of claim 1 further comprising a valve for selectively coupling said auxiliary condenser to the main air-cooled condenser.
4. The condenser apparatus of claim 1 wherein said first operating pressure is below one atmosphere of pressure, and said second operating pressure is at least one atmosphere of pressure.
5. The condenser apparatus of claim 1 further comprising a condensate pump connected to pressurize condensate from the main condenser, the auxiliary condenser connected to supply condensate downstream relative to the condensate pump.
6. The condenser apparatus of claim 1 wherein an operating pressure for said main air-cooled condenser ranges from approximately 0.5 psia to approximately 5.0 psia.
7. The condenser apparatus of claim 1 wherein an operating pressure for said auxiliary air-cooled condenser ranges from approximately 30 psia to approximately 100 psia or higher.
8. A combined cycle power plant comprising:
a gas turbine;
a heat-recovery steam generator receiving condensate and exhaust fluid from the gas turbine for producing steam;
a steam turbine selectively receiving the steam from the heat-recovery steam generator;
a main air-cooled condenser receiving the steam from the steam turbine and producing condensate;
a condensate pump for returning the condensate to the heat-recovery steam generator; and
a steam bypass circuit for selectively bypassing steam around the steam turbine, the steam bypass circuit having an auxiliary air-cooled condenser for passing the steam that bypasses the steam turbine, the auxiliary air-cooled condenser connected in parallel to the main air-cooled condenser and configured to operate at a pressure higher than an operating pressure of the main air-cooled condenser.