Characteristics of Mercury Re-emission and Migration in a Lab-Scale Wet Flue Gas Desulfurization Scrubber under Simulated Air and Oxy-Fuel Combustion Atmospheres

• Published in: Energy & fuels Vol. 34; no. 12; pp. 16356 - 16365
• Main Authors: Xu, Jialing, Bao, Jingjing, Liu, Hongtao, Yu, Jianghuai, Mo, Zhengyu, Xiang, Zhihua, Sun, Licheng
• Format: Journal Article
• Language: English
• Published: American Chemical Society 17.12.2020
• Subjects: Environmental and Carbon Dioxide Issues
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.0c03019

Based on a lab-scale wet flue gas desulfurization scrubber, mercury re-emission and migration during the desulfurization process were experimentally investigated under simulated air and oxy-fuel combustion atmospheres. The effects of O2, CO2, and metal ions were especially studied. The results show that adding O2 to a pure N2 atmosphere can remarkably enhance Hg0 re-emission because of an obvious decline of pH values, while the introduction of 75% CO2 to N2 atmosphere results in a limited Hg0 re-emission because of a lower pH drop. The re-emission of Hg0 is found to be slightly suppressed with increasing O2 concentration from 3 to 9% under air atmosphere and from 3 to 6% under oxy-fuel combustion atmosphere. Moreover, a further increase of O2 concentration to 12% has no significant impact on Hg0 re-emission under these two atmospheres. At a higher CO2 concentration, less mercury is re-emitted to the gas phase and more mercury is maintained in the solid phase. Under N2 atmosphere, metal ions such as Fe2+, Mn2+, and Ni2+ can intensify Hg0 re-emission in the order of Fe2+ > Ni2+ > Mn2+. However, the reduction of mercury is inhibited by metal ions under air and oxy-fuel combustion atmospheres. The inhibitory effect of Fe2+ is intensified with increasing CO2 concentration. It can be concluded that the existence of Fe2+ is more conducive to mercury control under oxy-fuel combustion atmosphere than that under air atmosphere.