Activated carbon based technology for the control of mercury emission from coal-fired power plants
The dynamics of sulfur-impregnated granular activated carbon (GAC) adsorbers for the uptake of vapor-phase mercury was evaluated as a function of key operating conditions. The effect of the sulfur impregnation method on mercury removal efficiency was examined through experiments conducted on commercially available sulfur-impregnated carbon (HGR) and carbon impregnated with sulfur in our laboratory (BPL-S). Although HGR and BPL-S possess similar sulfur contents, BPL-S is impregnated at a higher temperature which promotes a more uniform distribution of sulfur in the GAC pore structure. At low temperatures, HGR and BPL-S performed similarly in the removal of mercury vapor. However, as the temperature was increased above the melting point of sulfur, the performance of HGR deteriorated significantly, while the performance of BPL-S slightly improved. Temperature and the initial sulfur to carbon ratio (SCR) during production of BPL-S were the two control parameters for the impregnation proced ure. The results showed that carbons impregnated with sulfur at higher temperatures exhibited higher efficiency for mercury removal and that the impregnation temperature is the most important factor influencing the efficiency of these sorbents for mercury uptake.