Low-pressure feedwater heaters are exposed to the discharge pressure of which pump?

In a power plant, low-pressure feedwater heaters typically utilize thermal energy from steam extracted from the turbine to preheat the feedwater before it enters the boiler. The pressure of the steam supplied to these heaters correlates with the discharge pressure of the extraction pump, which is responsible for drawing steam from the turbine at various points during its operation. This steam is directed toward the feedwater heater, facilitating efficient heat transfer and enhancing overall plant efficiency.

Using an extraction pump allows for adjustable pressure and flow of the steam used in the heating process, making it suitable for low-pressure applications such as feedwater heaters. The other options listed refer to different functions where the discharge pressures do not align with the heating requirements of low-pressure feedwater heaters.

Thus, the correct choice emphasizes the role of the extraction pump in supplying steam for heating, underscoring its significance in optimizing the efficiency of the feedwater system.