Patent ID: 7927095

Claim:
A system for the real-time monitoring and control of a combustion process in the combustion zone of an industrial combustion chamber, wherein a fuel/oxidant mixture source provides a lean fuel/oxidant mixture characterized by a fuel/oxidant ratio for ignition and maintaining a combustion flame in the combustion zone during operation of the industrial combustion chamber, the system comprising: a sensor having a first electrode disposed adjacent the combustion zone; a ground electrode, the ground electrode disposed in the combustion zone and in spaced-apart relation to the first electrode; a voltage source for applying a time-varying voltage between the first electrode and the ground electrode and inducing a time-varying current between the first electrode and the ground electrode; circuit means for measuring the time-varying current; means for applying equivalent AC circuit analysis to an equivalent AC circuit and the time-varying current for determining the magnitude and phase angle of a voltage within the combustion flame using the time-varying current, and means for using the magnitude and phase angle of the voltage within the combustion flame to determine a complex impedance of the combustion flame, and means for determining a distance d of the combustion flame from the first electrode and determining the fuel/oxidant ratio of the fuel/oxidant mixture using the complex impedance of the combustion flame; and a controller coupled to the fuel/oxidant mixture source and responsive to the distance d and the fuel/oxidant ratio determined using the complex impedance of the combustion flame for adjusting the fuel/oxidant mixture and the distance d for optimizing the combustion process by reducing flame instability and pollutant emissions.