Economizer for Boiler

Economizer for Boiler

The primary role of a boiler economizer is to preheat the feedwater (water supplied to the boiler) using the residual heat from high-temperature flue gases emitted by the boiler.

Heat Recovery Process: After combustion, flue gases (typically 300–400°C or higher) flow through the economizer before exiting the chimney. The feedwater, which is at a lower temperature (e.g., from a deaerator or condensate system), circulates through tubes or plates within the economizer.

Heat Transfer: Heat from the flue gases is transferred to the feedwater through the economizer’s heat-transfer surfaces (tubes or fins), raising the feedwater temperature. This preheated water then enters the boiler’s drum or evaporator, reducing the energy required to convert it into steam.

Efficiency Boost: By recovering waste heat that would otherwise be lost through the chimney, economizers can increase boiler efficiency by 5–15%, depending on design and operating conditions.

Application Considerations

Flue Gas Characteristics: Ash content, temperature, and corrosiveness (e.g., sulfur in fuel causes acidic flue gases) dictate material selection (e.g., alloy steel for high temperatures, stainless steel for corrosion resistance).

Feedwater Quality: Poor water quality (e.g., high mineral content) can cause scaling inside tubes, reducing efficiency. Water treatment (e.g., demineralization) is often required.

Maintenance: Regular inspection and cleaning (to remove soot, ash, or scale) are critical to maintain performance. Blockages or fouling can lead to overheating of tubes and system failures.