Factors Impacting Gaseous Mercury Speciation in Postcombustion

Abstract

In the bench scale, gaseous mercury oxidization was investigated in postcombustion conditions with the experimental flue gas. The baseline experimental flue gas consisted of CO2 and N2. Other flue-gas constituents varied with O2, SO2, HCl, and NO. The measurement of mercury speciation was carried out at the downstream of the reaction tube using the Ontario Hydro method. Results showed that the possible intermediates Cl and Cl2 from HCl are the most important factors in mercury oxidization in the experimental flue gases. More mercury oxidization occurs with a higher reaction temperature and higher HCl concentration in most of experimental flue gases with HCl addition. O2 and NO also enhance mercury oxidization in the experimental flue gases with or without HCl and SO2. However, the effect of SO2 on mercury oxidization depends upon the presence of HCl.