CO₂ in natural gas combustion: relationship with O₂, lambda, and combustion quality

CO₂ is a key indicator for evaluating natural gas combustion. It is not examined in isolation, but together with O₂, CO, and lambda.

Relationship with O₂

As excess air increases, the percentage of CO₂ in the flue gas typically decreases, while O₂ increases.

High CO₂

It may indicate lower excess air, but it must always be verified that CO remains at safe levels.

Low CO₂

This is often associated with excessive air and higher flue gas losses.

Correct interpretation

The acceptable range is determined by the burner manufacturer and must be checked throughout the modulation range.