Modelling of pulverized coal combustion with respect to fly ash particle size distribution

Abstract

An approach is made to predict fly ash production and characteristics on the basis of: experimental information from a power plant tracking programme; and the results of a pulverized coal combustion model. Conclusions presented in this paper do not agree completely with previous experimental results obtained under laboratory simulated combustion conditions, or with generally accepted hypotheses about fly ash particle size configuration processes, showing the critical influence of individual particles temperature evolution on the final ash size distribution. The validity of a char fragmentation model, used extensively in fly ash size estimation, is also investigated. It is found that the presence of unburned particles in industrial fly ash must always be taken into account. It is also proved that model application must be restricted to a small number of cases that satisfy the global assumptions.