Optical probe based on flame emission spectroscopy is shown to be capable for the monitoring of gasifier.

There are obvious radical emissions in the impinging area, including OH^∗, H^∗, NO^∗, CO₂^∗, Na^∗ and K^∗ emissions.

The pathways of some radicals productions in gasifier have been explored.

With the increase of O/C, more reactions occur in the upward stream and OH^∗ can clearly reflect the changes.

The change rules of OH^∗ at the burner plane are similar to that of temperature and CO₂ concentration.