A digital imaging based multifunctional flame monitoring system

This paper presents an imaging-based multifunctional instrumentation system for the on-line monitoring and characterization of fossil fuel fired flames. The system includes an optical probe that transmits light from the flames in a furnace into an optical assembly, where the light is split into four beams in specific spectral ranges. Two high-performance monochromatic charge-coupled device cameras capture light from the flames and transmit the image signals to a microcomputer, where the signals are converted into digital images. Dedicated application software, incorporating novel digital image processing algorithms, two-color pyrometry, and power spectral analysis, has been developed to process the flame images. A range of flame parameters, including ignition point and area, spreading angle, brightness, nonuniformity, flicker, and temperature, are derived from the images. Experimental results obtained using a 1 MWth coal fired combustion test facility (CTF) demonstrate that the system is capable of providing instantaneous and quantitative measurement of the flame parameters on an on-line continuous basis. The flame parameters measured are found to be sensitive to combustion conditions, and therefore can be used as indicators of flame stability.