Deaerating Heater | Deaerator
Deaerator is one of the open type contact feed water heater used in boiler water treatment. It is the device that is widely used for the removal of oxygen and other dissolved gases from feed water supply to boiler.
The presence of dissolved gases like oxygen and carbon-dioxide in water makes the feed water corrosive, as they react with metal piping and other metallic equipments forming iron oxides (rust) where as dissolved carbon-dioxide combines with water to form carbonic acid that causes further corrosion. Deaeration is based upon ‘’DALTON and HENRY’’ which states that quantity of gas that dissolves in a liquid decreases as the temperature of the liquid increases and the quantity of dissolved gas becomes zero when temperature of liquid reaches the boiling point or saturation temperature i.e all the dissolved gases will be liberated, the above said process is called mechanical Deaeration. Complete oxygen removal from condensate cannot be attained by mechanical Deaeration, so in order to last traces of oxygen and other dissolved gases chemical Deaeration is required i.e by adding oxygen scavengers. Sodium sulphite (Na2SO3) or Hydrazine (N2H4) is injected in suitable calculated doses into feed water (i.e Deaerator outlet) at the suction of the boiler feed pump