What is the effect of excess air in the combustion process of a boiler?

Excess air in the combustion process of a boiler primarily introduces extra oxygen that is not needed for the complete combustion of fuel. When more air is supplied than necessary, it dilutes the combustion gases, leading to lower temperatures in the combustion chamber. This dilution can result in incomplete combustion, which reduces the overall efficiency of fuel use because more fuel is needed to achieve the same energy output.

In practical terms, when fuel efficiency is reduced, you end up consuming more fuel than required, which can increase operational costs and environmental impact. Ideally, the goal is to achieve a balanced air-to-fuel ratio that maximizes combustion efficiency, leading to optimal energy production with minimal waste.