Closed feedwater heaters are fed by the:

Closed feedwater heaters play a crucial role in improving the efficiency of a steam generation system by recovering and utilizing waste heat. They are specifically designed to heat the water that feeds into the boiler, using steam extracted from the turbine.

The correct choice indicates that closed feedwater heaters are fed by an open feedwater heater. This relationship highlights how the open feedwater heater uses condensate or low-pressure steam to pre-heat the cold water before it enters the closed feedwater heater. By transferring heat from one system component to another, the efficiency of the overall system is enhanced, as less energy is required to bring the feedwater to the requisite temperature before it enters the boiler.

In contrast, other options do not accurately define the source of water for closed feedwater heaters. For instance, feeding directly from the boiler would not be feasible, as the heater is intended to prepare water before it reaches the boiler. Similarly, a feed water valve is simply a mechanism to control the flow of water but isn’t the source itself. Finally, make up water lines typically bring in new water from an external source to compensate for system losses, not specifically directing water into closed feedwater heaters.

Understanding the interconnections in feedwater systems is essential for optimizing steam generation and