Which component is used to recover heat from flue gas to preheat feedwater?

• A. Economizer
• B. Deaerator
• C. Boiler drum
• D. Superheater

Answer: (A)

Recovering heat from flue gas to preheat feedwater is accomplished by the economizer. It’s a heat exchanger placed in the boiler’s exhaust path that transfers heat from the hot flue gases to the incoming feedwater. By raising the feedwater temperature before it enters the boiler, the economizer reduces the energy needed to produce steam and lowers stack losses, improving overall boiler efficiency. Other components serve different roles: a deaerator removes dissolved gases from feedwater, a boiler drum handles steam-water separation, and a superheater increases the temp of the steam after it leaves the drum. So the device designed to reclaim waste heat from flue gas for feedwater preheating is the economizer.