An economizer is an energy-saving device installed in the tail flue of a boiler. Its main function is to preheat the boiler feedwater by recovering waste heat from the flue gas, thereby improving the overall efficiency of the boiler system. Its core function is as follows:
1. Energy conservation and consumption reduction
Absorb low-temperature heat from boiler exhaust gas (usually at 250-350 ℃), significantly reduce exhaust gas temperature (usually to 100-150 ℃), and reduce heat energy waste. This can save more than 10% of fuel consumption and increase the thermal efficiency of coal-fired boilers to over 90%. 
2. Improve thermal efficiency
Preheat the boiler feedwater to near saturation temperature, reduce the energy demand of the subsequent evaporation heating surface, and optimize the thermal cycle efficiency. ‌
3. Protect equipment
Reduce the temperature difference when the feedwater enters the steam drum, reduce thermal stress, and extend the service life of the steam drum; At the same time, avoid the generation of acidic condensed water in the flue and reduce the risk of pipeline corrosion. ‌