Abstract

A method and system for determining flame characteristics in the time domain by analyzing the fluctuations of a time-domain output signal of a flame scanner monitoring a burner flame. A mean level (as well as maximum high and low levels) of the time-domain signal are determined during a predetermined time interval. Numerous intermediate levels are positioned between the mean level and the high and low levels. Several crossing numbers are obtained by counting how often the signal crosses the mean level and the intermediate levels during the time interval. These crossing numbers are plotted on a graph, wherein the crossing numbers are plotted against the relative distance between the levels. A curve is interpolated between the points thus obtained and an area under the curve is determined. The crossing numbers are normalized to the area to obtain normalized crossing numbers. Changes in these normalized crossing numbers are correlated with changes in specific flame characteristics of a particular burner operating under known conditions. Based on this correlation, observed changes in the normalized crossing numbers may then be used to recognize deviations from ideal combustion conditions. Parameters that can be monitored by this method and system include, but are not limited to, fuel-to-air ratio, combustibles and combustion efficiency.