How does a feedwater heater improve boiler efficiency?

A feedwater heater improves boiler efficiency primarily through the process of preheating feedwater using extraction steam. By utilizing steam extracted from the turbine or from the boiler itself, the feedwater heater raises the temperature of the water before it enters the boiler. This preheating reduces the amount of fuel required to heat the feedwater to the boiling point, which ultimately leads to a more efficient boiler operation.

When the feedwater is already warm, the boiler can produce steam more quickly and with less energy input, minimizing energy losses and enhancing overall thermal efficiency. This is particularly important in larger systems where the potential fuel savings can be significant, contributing to lower operating costs and improved sustainability of the energy systems.

The other options revolve around methods that do not directly concern the thermal efficiency improvements provided by a feedwater heater. For example, reducing the amount of steam used or increasing pressure in the steam lines may affect operation but do not relate to the feedwater temperature management that is essential for efficiency gains. Similarly, adding chemicals to the feedwater primarily addresses water treatment issues, such as preventing corrosion or scaling, rather than affecting the thermal efficiency of the boiler itself.