PREDICTING ASH BEHAVIOR IN UTILITY BOILERS

In recent years, significant advances have been made in the developmen t of methods to predict ash behavior in utility boilers. This paper pr ovides an overview of methods used to assess and predict ash formation and deposition. These prediction methods are based on a detailed know ledge of ash formation and deposition mechanisms that has been obtaine d through bench, pilot, and field testing and detailed coal and ash ch aracterization. The paper describes advanced methods of coal and ash a nalyses and the advantages of these methods over conventional methods. The advanced coal characterization methods provide sufficient data to predict size and composition distribution of fly ash. The composition and size data are used as inputs to mechanistic models which ultimate ly predict deposition propensities in various locations of utility boi lers. Advanced indices based on advanced coal analysis data have also been developed and are being applied to predict convective pass foulin g tendencies.