Improved coal-flame detection for safety and control. Phase 2 technical final report

The objective of the project was the development of an advanced optical approach which would indicate the presence of a coal flame and detect deviations from a desired setpoint. The technical approach was to use the characteristic radiation fluctuations from the base of a coal flame as an indicator of its presence. An on-line Fourier transform routine was used to extract the frequency vs. intensity characteristic. In the absence of a flame, the background radiation and radiation from other flame provides a markedly different frequency spectrum. Flame stoichiometry setpoint is determined by soot/coal particle measurements using two-color pyrometry. Testing was performed on flames that ranged from laboratory scale to large-scale coal combustors. The results indicated that a narrow viewing angle did provide an indication of flame presence through a unique radiation frequency vs. intensity relationship. The characteristic frequency was found to depend on flame type and scale.