2019 Volume 10 Issue 2 Pages 109-117
Substance flow analysis of mercury (Hg), Hg mass distribution and amount of Hg emissions were estimated at a 90 t/h small-scale industrial coal-fired boiler at the pulp factory in Guangdong province, China. Feed coal, bottom ash, electrostatic precipitator (ESP) ash,fabric filter (FF) ash, and limestone were sampled. The results showed that approximately 99% of Hg in the feed coal turned into gaseous Hg after the combustion process. More than 90% of the Hg was enriched in fly ash removal by ESP and FF, which is higher than corresponding values previously reported for other coal-fired power plants. The Hg input and Hg output as per the substance flow analysis in this study were found to be 12.12 kg (coal), 1.80 kg (limestone), 0.16 kg (bottom ash), 12.93 kg (fly ash), and 0.83 kg (stack). This result can be attributed to equipping the circulating fluidized bed boiler with an ESP and FF. The estimation results of Hg emission from the stack, computed using the mass balance model, were confirmed using previously published data, which showed an average error of -0.35% between the Hg output and Hg input. Using this ratio provided a result similar to the amount of Hg emitted from the stack. Therefore, the mass balance model is the most reliable method in the given context. Thus, the results proved that this model estimation remains a cost effective and quick way to study Hg emission from a coal-fired power boiler.
