Flame detection method, flame detector and flame detector operation

摘要

In the present invention there is disclosed a flame detection method being characterized by signal analysis for intensity variations in radiation emitted by a flame, wherein signals lying outside a certain frequency band are classified as interfering signals. The method is characterized by analysis of frequency in radiation change, whereby a mid-frequency ({omega}imp, {omega}imc) for intensity variations in radiation and cut-off frequency ({omega}igp, {omega}igc) for intensity variations in radiation are analyzed and classified as periodic or non-periodic signals, whereby the periodic signals with the mid-frequency ({omega}imp) of the intensity variations in radiation above a first frequency value (Gi1) and the non-periodic signals with the cut-off frequency ({omega}igc) of the intensity variations in radiation above a second frequency value (Gi2) are classified as interfering signals. The first frequency value (Gi1) is determined by the flicker frequency of a stationary flame having a magnitude corresponding to a flame of minimum magnitude to be detected and the second frequency value (Gi2) is selected greater than the first frequency value (Gi1). A flame detector for carrying out the above-described method comprises at least one flame-radiation sensor (1), and evaluation circuitry connected to the sensor for analyzing the sensor signal, whereby the evaluation circuitry comprises means for analysis of a received radiation and a mid-frequency ({omega}imp, {omega}imc), a cut-off frequency ({omega}igp, {omega}igc) thereof for intensity variations in radiation, and means for connecting sensor (1) signals with these frequencies. In the present invention, there is also claimed operation of the invented flame detector containing a fuzzy control unit with evaluation criteria for such fuzzy control unit.