Economizer is the best mechanical component which is used for trapping the heat of flue gasses. Economizers can be best applied in electricity generating power plants. Best way of
utilisation of flue gas heat is by transferring it to the boiler feed water. Hence economizers are designed in such a way that feed water is allowed to pass the economizer through pipes. Economizer shell is completely filled with the flue gasses. There is a cross flow heat exchange process takes place between boiler feed water and flue gas.