PREDICTING ASH BEHAVIOR IN UTILITY BOILERS

In recent years, significant advances have been made in the development of methods to predict ash behavior in utility boilers. This paper provides an overview of methods used to assess and predict ash formation and deposition. These prediction methods are based on a detailed knowledge of ash formation and deposition mechanisms that has been obtained through bench, pilot, and field testing and detailed coal and ash characterization. The paper describes advanced methods of coal and ash analyses 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 ultimately predict deposition propensities in various locations of utility boilers. Advanced indices based on advanced coal analysis data have also been developed and are being applied to predict convective pass fouling tendencies.