Which statement best describes the operation of a closed feedwater heater?

A closed feedwater heater operates by utilizing a heat exchanger system where steam is used to transfer heat to the feedwater without the two fluids coming into direct contact. This process involves steam flowing through one side of the heat exchanger while the feedwater circulates through the other side. As the steam condenses, it transfers its thermal energy to the feedwater, raising its temperature before it enters the boiler.

The key aspect of a closed feedwater heater is that the steam and the water do not mix; they remain separate throughout the heating process. This ensures that the feedwater can be heated efficiently without any contamination from the steam or any potential carryover of steam impurities into the feedwater.

This distinction is important in the context of boiler operations because it helps in maintaining the quality of the feedwater, hence ensuring efficient and safe operation of the boiler system. Since the statement emphasizes this separation of phases, it accurately describes a fundamental characteristic of closed feedwater heaters.