Combined Cycle Power Plant: How It Works

Inner Workings of a Combined-Cycle Power Plant

A combined-cycle power plant uses both a gas and a steam turbine together to produce up to 50 percent more electricity from the same fuel than a traditional simple-cycle plant. The waste heat from the gas turbine is routed to the nearby steam turbine, which generates extra power.

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How a Combined-Cycle Power Plant Produces Electricity

This is how a combined-cycle plant works to produce electricity and captures waste heat from the gas turbine to increase efficiency and electrical output.

  1. Gas turbine burns fuel.

    • The gas turbine compresses air and mixes it with fuel that is heated to a very high temperature. The hot air-fuel mixture moves through the gas turbine blades, making them spin.
    • The fast-spinning turbine drives a generator that converts a portion of the spinning energy into electricity.
  2. Heat recovery system captures exhaust.

    • A Heat Recovery Steam Generator (HRSG) captures exhaust heat from the gas turbine that would otherwise escape through the exhaust stack.
    • The HRSG creates steam from the gas turbine exhaust heat and delivers it to the steam turbine.
  3. Steam turbine delivers additional electricity.

    • The steam turbine sends its energy to the generator drive shaft, where it is converted into additional electricity.

Heavy-Duty Gas Turbines 

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