How is the amount of excess air in gases of combustion typically determined?

The determination of excess air in combustion gases is primarily achieved through the analysis of oxygen (O2) levels in the flue gas. When air is used in the combustion process, it contains both oxygen and nitrogen. The ideal combustion process would have enough oxygen present to react completely with the fuel, but in practice, it’s common to have more air than is theoretically necessary. This excess air ensures that the fuel burns completely, minimizing emissions of unburned hydrocarbons and other pollutants.

By measuring the amount of oxygen remaining in the exhaust gases after combustion, engineers can calculate how much excess air is being supplied relative to the stoichiometric (ideal) amount required for complete combustion. If the analysis shows a lower than expected O2 concentration, it indicates that less excess air is present, while a higher O2 concentration suggests more excess air was utilized. This analysis is crucial for optimizing combustion efficiency and reducing emissions.

In contrast, the analyses of CO2, NOx, and SO2 do provide valuable information about the combustion process and emissions, but they do not directly indicate the presence of excess air in the same way that oxygen analysis does. CO2 levels can indicate efficiency and fuel usage, while NOx and SO2 are linked to specific types of