Partitioning characteristics and particle size distributions of heavy metals in the O2/RFG waste incineration system

This study applies the oxygen/recycled flue gas (O-2/RFG) combustion technology for waste incineration and investigates the effects of different RFG rates on the concentrations of gas pollutants as well as the partitioning characteristics and particle size distributions of five heavy metals (Cr, Cu, Pb, Zn. and Cd). Experimental results show that the combustion efficiency can be improved and the concentration of CO2 is increased by appropriately controlling the RFG rate in the O-2/RFG incineration system. The partitioning characteristics and size distributions of heavy metals in O-2/RFG combustion system are different from those in general air combustion system. Under O-2/RFG combustion system, the partitioning percentages of heavy metals in sand bed, bottom ash, and collected ash are increased. The particle size distributions of heavy metals display the triple-peak curves. As the RFG rate rises, the concentrations of volatile heavy metals are increased in small-size (<1 mu m) fly ash, decreased in medium-size (1-10 mu m) fly ash and increased in large-size (>10 mu m) fly ash. These phenomena will benefit to increase the overall control efficiency of heavy metals in the incineration system. (C) 2009 Elsevier B.V. All rights reserved.