In-Situ Monitoring of Toxic Heavy Metals from RDF Combustion by Two-Dimensional Atomic Absorption Spectrometry

The method to visualize two-dimensional (2D) distributions of heavy metals in refuse-derived fuel (RDF) combustion flame by using 2D atomic absorption spectrometry (2D-AAS) was studied. In-situ monitoring of the heavy metal vaporization was performed to gather useful information on the reduction of their emissions. The RDF sample was burned on a burner with an O₂/N₂ gas mixture being supplied from the bottom. Easily vaporized metals such as mercury (Hg) and cadmium (Cd) present in the RDF flame were measured by 2D-AAS. In order to measure the atomic absorption of lead (Pb), a sub-burner supplying O₂ was placed in the RDF flame. O₂ reacts with unburned gases in the RDF flame, increasing the flame temperature locally. Consequently, atomic absorption of Pb became measurable, and its 2D profiles were obtained by mapping. In addition, quantitative analyses of Hg and Cd contained in the RDF were made using the standard addition method without any pretreatments.