Time varying voltage combustion control and diagnostics sensor

A method for the real-time monitoring and control of a combustion process in the combustion zone of a combustion chamber, wherein a fuel/oxidant mixture characterized by a fuel/oxidant ratio is directed into the combustion zone via a fuel/oxidant inlet and is ignited for maintaining a combustion flame in the combustion zone, the method comprising the steps of:

• providing a sensor having a first electrode and a ground disposed adjacent the combustion zone, wherein the combustion flame is disposed a distance d from the first electrode;
• applying a time-varying voltage to the first electrode and measuring a time-varying electric current between the first electrode and the ground, wherein the time-varying electric current varies with the position of the combustion flame from the first electrode within the combustion zone along a sensor axis;
• using equivalent AC circuit analysis with an equivalent AC circuit and with the time-varying electric current between the first electrode and the ground to determine the magnitude and phase angle of a voltage within the combustion flame, and using the magnitude and phase angle of the voltage within the combustion flame to determine a complex impedance of the combustion flame;
• determining the 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
• adjusting the fuel/oxidant mixture for adjusting the distance d and the fuel/oxidant ratio for optimizing the combustion process by reducing flame instability and pollutant emissions.

A method for the real-time monitoring and control of a combustion process in the combustion zone of a combustion chamber, wherein a fuel/oxidant mixture characterized by a fuel/oxidant ratio is directed into the combustion zone via a fuel/oxidant inlet and is ignited for maintaining a combustion flame in the combustion zone, the method comprising the steps of:

• providing a sensor having a first electrode and a ground disposed adjacent the combustion zone, wherein the combustion flame is disposed a distance d from the first electrode;
• applying a time-varying voltage to the first electrode and measuring a time-varying current between the first electrode and the ground, wherein the time-varying current varies with the position of the combustion flame from the first electrode within the combustion zone along a sensor axis;
• using equivalent AC circuit analysis with an equivalent AC circuit and with the time-varying current between the first electrode and the ground to determine the magnitude and phase angle of a voltage within the combustion flame and the magnitude and phase angle of a voltage across the distance d, where the equivalent AC circuit represents the combustion flame as resistance only, and where the equivalent AC circuit represents the distance d between the first electrode and the combustion flame as capacitance only, and where the equivalent AC circuit includes a baseline resistance and a baseline capacitance respectively corresponding to the resistance and capacitance of other components and connections within the combustion system, and where the equivalent AC circuit places the distance d and the combustion flame in series, and places the baseline resistance and the baseline capacitance in parallel with each other and with the distance d and the combustion flame;
• using the magnitude and phase angle of the voltage within the combustion flame to determine a complex impedance of the combustion flame;
• using the magnitude and phase angle of the voltage across the distance d to determine the distance d, and determining the fuel/oxidant ratio of the fuel/oxidant mixture using the complex impedance of the combustion flame;
• and
• adjusting the fuel/oxidant mixture for adjusting the distance d and the fuel/oxidant ratio for optimizing the combustion process by reducing flame instability and pollutant emissions.