A deaerator is a device that is widely used for the removal of oxygen and other dissolved gases from the feedwater to steam-generating boilers. In particular, dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). Dissolved carbon dioxide combines with water to form carbonic acid that causes further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.005 cm³/L) or less as well as essentially eliminating carbon dioxide.
There are two basic types of deaerators, the Termochimica spray & tray-type and the Stork spray-type:
The Termochimica spray&tray-type (also called the cascade-type) includes a vertical or horizontal domed deaeration section mounted on top of a horizontal cylindrical vessel which serves as the deaerated boiler feedwater storage tank.
The Stork spray-type consists only of a horizontal (or vertical) cylindrical vessel which serves as both the deaeration section and the boiler feedwater storage tank.
Deaerator Working Principle
In the Boiler deaerator Working Principle Water is heated close to saturation temperature with a minimum pressure drop and minimum vent. This ensures the best thermal operating efficiency. Deaeration is done by spraying the boiler feed water over multiple layers of trays designed to provide large contact area of the liquid surface to Pegging steam. This scrubbing steam is fed from the bottom of the deaerator when it contacts with BFW, it heated up to saturation temperature dissolved corrosive Gases released from feed water with some vapors from the vent valve. Then treated water falls to the storage tank below the deaerator.