Study on the mechanism of lead release from ash under the action of high-temperature flue gas

Abstract

The interaction between flue gas and ash causes the redistribution of heavy metals and affect their emission characteristics. In this study, a double-layer fixed-bed reactor was used to investigate the effect of this interaction on Pb distribution at 800–1000 °C. Obvious gaseous Pb adsorption by ash just occurred in the case of high-Pb flue gas and less ash melting. In other cases, significant Pb release from ash occurred under the action of the high-temperature flue gas. The occurrences of Pb in ash was found to be thermally stable. Ash melting is the main reason for the Pb release. Gaseous Na in the combustion flue gas and reducing components in the pyrolysis flue gas promote the Pb release via promoting the ash melting. H2S and HCl in the pyrolysis flue gas also promote the Pb release by forming PbS and PbCl2, which are more volatile.