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

The primary purpose of an economizer in a boiler system is to preheat the water before it enters the boiler. By recovering waste heat from the flue gases, the economizer enhances the overall efficiency of the boiler. This preheating process reduces the amount of energy required to bring the water to its boiling point, allowing for more efficient fuel use and lower operating costs.

Using an economizer not only leads to better fuel efficiency but also contributes to reduced emissions, as less fuel consumption results in lower carbon output. This function is critical in optimizing the performance of the boiler system and ensuring that it operates at its best efficiency level.

In contrast, other options represent different functions or equipment that do not align with the primary operation of an economizer. For example, cooling exhaust gases, increasing steam pressure, and filtering impurities do not relate to the specific role of an economizer within the boiler system.