What is the function of an economizer in a boiler?

The function of an economizer in a boiler is to recover waste heat from the flue gases produced during combustion and use that heat to preheat the feedwater before it enters the boiler. This process enhances overall thermal efficiency by utilizing energy that would otherwise be lost, thereby reducing fuel consumption and improving the efficiency of the boiler system. By increasing the temperature of the feedwater, the economizer allows the boiler to require less energy to convert this water into steam, ultimately leading to savings in operating costs and a reduction in emissions.

The other options do not accurately describe the role of an economizer in a boiler system. Cooling steam before it reaches the turbine, increasing steam pressure, or storing excess steam are functions related to different components in the steam cycle or system, but they do not reflect the primary purpose of an economizer, which focuses specifically on heat recovery for feedwater preheating.