New York Low Pressure Boiler COF Practice

If you are reading 12% CO2 on a combustion analyzer, what does it indicate?

1. Complete combustion

2. Incomplete combustion

3. Good efficiency

4. Excess air

The correct answer is: Incomplete combustion

When a combustion analyzer indicates 12% CO2, it suggests that there is a significant amount of carbon dioxide produced during the combustion process. While CO2 is a product of complete combustion, the actual percentage must be interpreted in the context of other factors, such as the type of fuel used and the air-fuel ratio. In an ideal situation of complete combustion, we would expect higher levels of CO2, especially in natural gas combustion where levels can reach 10% to 12% or higher. However, if CO2 levels are lower than expected, it can indicate that there is unburned fuel present, or that the combustion process is not fully efficient, leading to incomplete combustion. Consequently, maintaining lower CO2 levels correlates directly to the issues of incomplete combustion, as it suggests that not all fuel is being converted to CO2, resulting in the possibility of producing harmful byproducts such as carbon monoxide (CO). A reading of 12% CO2 generally signals that there is insufficient combustion efficiency and points towards incomplete combustion, making this the most appropriate interpretation for this situation.