Economizer is sandwiched in the boiler flue inside, there are a lot of pipes back and forth, inside is hot water, outside is high temperature flue gas, through the pipeline to complete the heat exchange, so that the water heating, flue gas cooling.

Although water has been supplied to the lowest visible water level of the water gauge before the ignition of the boiler, but after the ignition, due to the rise of the temperature of the furnace water, volume expansion makes the water level rise.

With the further increase of boiler water temperature, steam is gradually generated in the water wall, and the water level of the boiler rises further. That is to say, the boiler does not need to fill water for a long period of time from the beginning of the ignition. If there is no water flow in the economizer, it may be damaged because of overheating.

The economizer is usually composed of supporting frame, cast iron fin pipe with flange, cast iron elbow or serpentine pipe, etc., installed in the flue gas pipe at the tail of the boiler. After the water enters the economizer, the heat exchange with high temperature flue gas increases the water temperature.

The heat exchanger that uses the waste heat from the exhaust of the boiler to heat the feed water is called the economizer. After the boiler is installed, the economizer can reduce the exhaust temperature, improve the boiler efficiency, and can improve the feed water temperature into the drum, ensure the normal water circulation of the boiler, and make the evaporation heating surface to improve the steam production, at the same time, improve the working conditions of the drum.