Measurement and modeling of heavy metal behaviors during the incineration of RDF in a pilot-scale kiln incinerator-Part 1: Modeling using multizonal thermodynamic equilibrium calculation

Abstract Multizonal thermodynamic equilibrium calculation is one of the methods used in estimating or explaining the fate of elements such as heavy metals during waste incinerations and probably only one method that can estimate the fate of trace elements, but the ability of the calculation as a fate-estimation tool was not fully examined. This study examines the performance of multizonal thermodynamic equilibrium calculation applied to waste incineration by comparing the calculated results with the results from the incineration test and literature information. High temperature behaviors of the heavy metals were also reviewed to correctly understand their gas phase speciation in the incinerator, and the thermodynamic data of gaseous Cd species were modified to better reproduce the high temperature vaporization behavior. The calculation represented the high volatility of Hg, Cd, Pb, and low volatility of Cr in the incineration, whereas the measured high volatility of Zn and As could not be obtained by the calculation. The calculation succeeded in reproducing the possible gas phase chemical speciation of heavy metals in the incinerator expected from the review on the high temperature properties, whereas the calculated fly ash speciation does not match with the measured speciation. Possible reasons for these inconsistencies were considered.