Non-linear characteristics on carbon content of fly ash for different size particles in pulverized coal boiler

The amount of residual carbon in fly ash is important for thermal efficiency and safe operation of the boilers, performance of generator unit and utilization of fly ash. The experimental investigation on the relationship between residual carbon content of fly ash and particle size was carried out. A non-linear relationship between unburned carbon content and particle size was observed. It is shown as a typical variety tendency that the carbon content decreases and then increases with the decrease of particle size. The validation works, which concluded comparing with the exiting researches, instances for different sampling conditions, power plants and coals were performed to confirm the present variety tendency. The rationality of the phenomenon reported was affirmed according to exiting experimental data on respects of coal-related factors and boiler-related factors. Moreover, the possible reasons for this non-linear variation trend were obtained by mechanism analysis. © 2009 Chin. Soc. for Elec. Eng.