Numerous economic and environmental factors are accelerating development of tighter controls for utility boilers. Such control may not be possible, however, with conventional technology alone. Advanced boiler optimization systems are a key part of these controls, and it is now recognized that accurate burner monitoring can be of great benefit to successful boiler optimization. This is particularly true for advanced low NOx (nitrogen oxides) burners because they are more sensitive to changes in coal quality and boiler operation. Continuous monitoring is especially crucial because significant shifts in flame quality can occur in just a few minutes due to unexpected changes in fuel and furnace operation. Engineers and boiler operators have long recognized that optical flame flicker patterns are correlated with burner emissions performance and flame quality. Several attempts have been made to develop burner monitoring systems based on conventional statistical and time series analysis of the optical flame flicker patterns. These systems have met with limited success, however, because the flicker patterns reflect the highly complex and nonlinear nature of the underlying combustion process. Over the last decade, Babcock & Wilcox Power Generation Group, Inc. (B&W PGG) has worked with researchers from the Oak Ridge National Laboratory (ORNL) to develop a new approach for analyzing the optical flicker patterns from burner flames. This new approach relies on advanced analysis techniques from the field of nonlinear dynamics, chaos and nonlinear systems theory. This paper will discuss the application of these new techniques to optical signals from burner flames. The paper will also present field results showing how the application of this new monitoring approach can lead to significant reductions in emissions and an improvement in efficiency.
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