The boiler economizer can reduce the temperature of the flue gas, recover the heat of the flue gas, improve the thermal efficiency of the boiler, and save the fuel. Superheater outlet flue gas temperature of about 700 DEG C, even after the superheater arranged a large number of convection tubes, because water temperature is saturated temperature of drum pressure, the smoke from the convection tube temperature is up to 250 ~ 350 DEG C, the flue gas also contains a lot of heat. The installation of economizer after superheater or convection tube bundle can effectively reduce the temperature of flue gas, recover a lot of heat and save a lot of fuel, because the early boiler usually uses coal as fuel, so it is called economizer.
After the economizer is installed in the boiler, the temperature of the water supply to the drum is greatly improved. For the boiling economizer, the inlet temperature of the drum is the saturation temperature under the drum pressure. For the non boiling economizer, the feed temperature of the drum is not yet achieved, but it also approaches the saturation temperature. Therefore, to the heating water economizer, due to the saturation temperature of water temperature is equal or close to the drum under pressure, can be reduced due to the temperature difference caused by thermal stress, improve the working conditions of the drum.