Carbon dioxide, oxygen, nitrogen, hydrogen sulphide and methane may be dissolved in water.
Except for nitrogen, which is an inert gas, all these gases are undesirable in the water used to supply the steam generators and must therefore be eliminated.
Elimination of these gases can be achieved by means of:
Thermal and thermophysical method: tend to reduce gas solubility and expel them from water.
Chemical method: uses chemicals capable of reacting with the gases to be eliminated.
The deaerator is an equipment that removes gases dissolved in water by thermal or thermophysical method.