What is Stoichiometric Combustion in a Boiler ?

Stoichiometric Combustion is the ideal combustion where at the end of the combustion process no fuel or air is left behind.  Thus all the carbon in the fuel is converted to carbon dioxide and the sulphur is converted to sulphur dioxide.  If residues such as carbon, carbon monoxide or sulphur remain, then the combustion is not stoichiometric.

Stoichiometric combustion cannot be achieved practically.  By adjusting the air/fuel mixture, the actual combustion can be made as close to the stoichiometric combustion as possible.