Release behavior of Hg, Se, Cr and as during oxy-fuel combustion using Loy Yang brown coal in a bench-scale fluidized bed unit

This experimental study investigates, for the first time, the fate of trace elements (Hg, Se, Cr and As) during combustion of Loy Yang brown coal in a large bench-scale oxy-fuel fluidized bed. The results indicated that up to 70%, 28%, 7% and 2% of total As, Cr, Se, and Hg respectively were retained in the collected ash at 15-30% oxygen concentration in the oxy-fuel combustion atmosphere at around 850°C. With the increase in oxygen concentration in oxidant, the Hg adsorption in ash was found to decrease. Compared to bed ashes, higher Hg adsorption was observed in fly ashes containing higher carbon content. Therefore, a higher level of Hg capture is expected in oxy-fuel circulating fluidized bed combustion due to the circulating materials having higher carbon content.