Let us calculate stoichiometric amount of air for combustion of solid fuel of composition 84%C, 5%H, 5% moisture and 6% ash, per kg of coal. Following the stoichiometry of combustion, the amout of air would be

Note

In the above example if actual amount of air is 0.5 moles then

We can also call- that 110.62% theoretical air is used for combustion.

Note: Complete combustion can occur only when amount of air is equal to or greater than stoichiometric air. When excess air is used, POC will contain  in addition to  and   and SO₂