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.