New York Low Pressure Boiler COF Practice

A reading of 12% CO2 indicates what type of combustion process?

1. Complete combustion

2. Incomplete combustion

3. Excess air combustion

4. Efficient combustion

The correct answer is: Incomplete combustion

A reading of 12% CO2 in flue gases typically suggests an incomplete combustion process. In an ideal complete combustion scenario, fuels such as natural gas would produce more significant amounts of CO2, often leading to readings of 12% CO2 or higher, particularly when there is adequate air for combustion. When combustion is complete, the fuel burns efficiently, converting most of the carbon in the fuel to CO2. However, if the combustion is not occurring properly—due to insufficient air supply, poor mixing, or other factors—the combustion process cannot fully convert the fuel into CO2. Instead, some carbon is left unburned or is converted into carbon monoxide (CO) or other hydrocarbons, resulting in lower CO2 readings. Thus, a lower CO2 level, such as 12%, is indicative of inefficiencies in the combustion process, highlighting that it is incomplete. Understanding this is crucial for operations and maintenance within boiler systems, as addressing incomplete combustion can improve efficiency, safety, and reduce emissions.