Flame ignition and monitoring system and method

Abstract

A system and method for igniting and monitoring a pilot flame for a burning of waste gas, such as the waste gas of an oil refinery or drilling rig, includes a current which is pulsed periodically with pulses of approximately one-second duration of electric power resulting in the outputting of an igniter electrode assembly of typically 6000 volts AC at 20 milliamperes at an alternating current frequency of typically 60 Hz. During the presence of a pilot flame, ionization of gas takes place resulting in a rectification of ignition current. The transformer has a monitoring winding outputting a signal from which a 60 Hz component is filtered out, the remaining signal having a sequence of pulses which varies between positive and negative intervals of the alternating current excitation. Comparison of the pulses provides for an indication of flame absence in the presence of equality of the pulses, and flame presence in the presence of an ineqality of the pulses. Pulse signals appearing in harmonics of the interaction in the flame plasma show spectral components in the range of 240 to 360 Hz.

Dependencies are inferred from the claim text.