Removal of elemental mercury from flue gas by recyclable CuCl2 modified magnetospheres from fly ash: Part 5. Industrial scale studies at a 50 MWth coal-fired power plant

Abstract

The mercury removal performance of a low-cost recyclable CuCl2 modified magnetospheres (Cu-MF) was investigated at a 50 MWth coal-fired power plant. An increase in the Cu-MF injection rate facilitated the mercury removal and recovery process. With the combination of the existing pollutant control devices and the Cu-MF injection, an overall mercury removal efficiency of 99.3% could be achieved. Under optimal conditions, the mercury emitted from the stack was reduced to 0.10 μg/m3. Most of the mercury in the flue gas migrated to the fly ash with the spent Cu-MF. Subsequently, through magnetic separation, 67.4% of the input mercury could be recovered. The comparison of experimental results showed that Cu-MF was more effective than fly ash in removing and recovering mercury from the flue gas. With the injection of Cu-MF, HgCl2 was formed on the magnetospheres and was identified by the mercury-temperature-programmed decomposition (Hg-TPD) experiments. The magnetospheres with the lowest particle size showed the highest mercury removal capacity. This work is expected to provide valuable guidance for optimising the mercury removal technology in large scale commercial applications in future.