The Role of Fin Tubes in an Economizer
This is where the connection to our previous discussion becomes clear. Economizers are a prime example of a fin tube heat exchanger.
- Why Fins? Flue gas is a poor conductor of heat. To efficiently transfer heat from the gas to the water inside the tubes, the surface area on the gas side must be dramatically increased.
- The Design: An economizer is typically a bank of finned tubes through which the feedwater flows. The fins are on the outside, exposed to the hot flue gases.
The most common types of fin tubes used in economizers are:
- Welded Fins: For high-temperature and corrosive environments, using materials like carbon steel or stainless steel.
- Extruded Fins (Bimetal): Very common, where an aluminum fin is extruded over a steel tube, offering an excellent balance of efficiency and cost.
H-Finned Tubes: Used in very dusty flue gas (e.g., from coal or biomass) as the design is less prone to plugging and is easier to clean