What is the primary function of an economizer in a boiler system?

The primary function of an economizer in a boiler system is to absorb heat from the flue gases before they are expelled, and use this recovered heat to preheat the feedwater entering the boiler. By raising the temperature of the feedwater, the economizer improves the overall efficiency of the boiler system. This preheating process means that less fuel is required to bring the water to its boiling point, which ultimately enhances the overall thermal performance of the boiler.

The option regarding cooling combustion gases before they reach the superheaters does not describe the role of an economizer, as it primarily focuses on heat recovery rather than cooling. The option mentioning heating incoming combustion air, while relevant in the context of efficiency, relates more to air preheaters rather than economizers. Lastly, the option concerning the regulation of steam flow pertains to other boiler components that manage steam pressure and flow, not the economizer's function. Understanding these distinctions clarifies why the correct choice is focused on heat recovery for preheating feedwater, emphasizing the economizer's role in enhancing boiler efficiency.