What boiler component preheats the feedwater before it enters the steam drum?

The economizer is a vital component in a boiler system that preheats the feedwater before it enters the steam drum. Its primary function is to enhance the overall efficiency of the boiler by capturing some of the waste heat from the flue gases that exit the boiler. This recovered heat is transferred to the cold feedwater, raising its temperature significantly before it is introduced into the steam drum.

By preheating the feedwater, the economizer reduces the amount of energy required to turn the water into steam, which leads to improved fuel efficiency and reduced operational costs. Additionally, preheated feedwater facilitates a more effective and rapid steam generation process, thereby enhancing the boiler's responsiveness to demand.

In contrast, the condenser typically serves to convert steam back into water in a separate process, the reheater is used to raise the temperature of steam after it has expanded in the turbine but before it returns for another cycle, and heat exchangers can serve a variety of functions not specifically geared toward the preheating of feedwater in the boiler context.