What is the main function of a heat recovery steam generator?

A heat recovery steam generator (HRSG) primarily serves the purpose of capturing exhaust heat from a gas turbine to produce steam. In a combined cycle power plant, for instance, the gas turbine generates electricity and expels hot gases as a byproduct. The HRSG utilizes these exhaust gases to heat water and convert it into steam, which can then be used to drive a steam turbine for additional power generation. This process enhances the overall efficiency of the system by using waste heat, which would otherwise be lost, thereby maximizing energy output while minimizing fuel consumption.

The main role of the HRSG is integral to the operation of energy-efficient systems, particularly in combined cycle plants, where it significantly contributes to energy recovery and utilization. By capturing and utilizing waste heat, the HRSG helps to improve the thermal efficiency of the power plant, leading to reduced operational costs and lower environmental impact.