A New Flame Monitor with Triple Photovoltaic Cells

Presented in this paper is a new flame monitor that uses three photovoltaic cells covering UV, visible and IR spectral bands respectively. A gain adjustable amplifier is incorporated into the monitor so that it is applicable to coal, oil or gas fired flames. Self-checking of the monitor is implemented through cross-correlation of the signals from the three cells and hence no additional self-checking hardware is required. Both flickering frequency and brightness of the flame are determined to monitor flame stability and to detect flame presence as well as sighting tube blockage. Unlike conventional single cell flame detectors, the new multi-cell device can still be in operation before being repaired after a cell-failure alarm has gone off. Experiments carried out on an industrial scale combustion test facility demonstrate the advantages of the new flame monitor over conventional flame detectors