Deaeration of Boiler Water

Deaeration refers to the process of removing dissolved gases such as oxygen and carbondioxide from the water.  Dissolved Oxygen in Water causes corrosion by the formation of rush on the surfaces of the boiler and the piping (rust).  Carbondioxide which is dissolved in the water forms carbonic acid which also causes corrosion. 

Hence, it is essential that these two gases are removed from water.

Deaerators can be classified into
Mechanical Deaerators
These Deaerators separate the gases by a mix of high temperature and mechanical action
Chemical Deaerators
Chemical deaerators work by passing the water through chemicals which absorb the oxygen and the carbondioxide.
Vacuum Deaerators
Membrane Contractors
Membrane Contractors work by passing the water through hollow fibres.  The water is made to pass on the outside of the hollow fibre.  A vacuum is created on the inside.  The gases pass through the membrane on to the inside and drawn into the vacuum pump.