What is the primary function of a heat recovery steam generator (HRSG)?

The primary function of a heat recovery steam generator (HRSG) is to capture waste heat from gas turbines to produce steam. In a combined cycle power plant, gas turbines produce electricity and emit hot exhaust gases. Instead of allowing this waste heat to escape unutilized, an HRSG uses it to heat water, generating steam that can be fed into a steam turbine, further enhancing overall efficiency and output of the power plant.

This process exploits the energy that would otherwise be wasted, making it a critical component in increasing the efficiency of energy production. The ability to recover and utilize waste heat contributes significantly to the economic and environmental performance of power-generating systems.

While directly generating electricity may involve the overall system's outputs, the focus of the HRSG itself is on steam production from waste heat. Cooling steam and filtering impurities are important functions in other parts of the thermal cycle but are not the primary purpose of the HRSG.