A Boiler Economizer is a mechanical device designed to recover waste heat from the hot flue gases leaving a boiler. It uses this heat to preheat the feedwater being pumped into the boiler.
- Core Function: To improve the efficiency of a boiler system.
- Simple Analogy: Think of it as a “pre-heater” for the boiler. Instead of sending cold water to the boiler, you send warm water, so the boiler uses less fuel to turn it into steam.
How Does it Work?
The principle is straightforward:
- Hot Exhaust Gases: After the flue gases have passed through the main part of the boiler, they are still very hot (often between 400°F and 900°F / 200°C and 480°C). Sending this heat up the stack is a waste of energy.
- Cold Feedwater: The water returning to the boiler from the condensate system is relatively cold (e.g., 200°F / 93°C).
- Heat Exchange: The economizer is installed in the flue gas path, just before the stack. The cold feedwater is pumped through the tubes of the economizer, while the hot flue gases pass over the outside of the tubes.
- Result:
- The feedwater is heated before it enters the boiler.
- The flue gases are cooled before being exhausted to the atmosphere.