Composition of Air Combustion in Steam Boiler

The steam boiler must have sufficient supply of air to make combustion properly. Air is one of three important parts for combustion to take place, Air-Fuel-Heat. The air for combustion contains based on volume, 21% Oxygen (O₂) and 79% Nitrogen (N₂). The Nitrogen does not have any role and is not chemically active in the process of combustion steam boiler, through the furnace without any changes and carries away the heat.

All fuels commonly contain three substances, carbon, sulphur and hydrogen. Combustion of pure carbon in air has three possibilities:

1.      If combustion is not supplied by enough air, some of the carbons will burns incompletely and form unburned fuel carbon monoxide (CO) blowing out of the stack and probably smoke in the combustion product of steam boiler.

2.      If combustion is supplied by enough air, oxygen will be fused with the carbon to be burned together completely to form carbon dioxide (CO₂).

3.      If combustion is supplied by too much air, it will cools the furnace, the flame is cooler, short and clear also there is not enough heat will be produced. Too much excess air give possibility that at given firing rate could result in unstable fires in steam boiler.

Sufficient air must be provided to the furnace of steam boiler to make perfect combustion. Air should be supplied under the right control and not to leak into the steam boiler through holes, cracks, and the like.