Mercury emission control in coal-fired plants: The role of wet scrubbers

When coal is combusted, the combination of the elevated temperature and the volatility of mercury and its compounds results in the presence of gaseous elemental mercury and mercury compounds in the combustion flue gas. In January 2005, the European Commission adopted a mercury strategy that envisages a number of measures to reduce mercury levels in the environment and human exposure. A number of options for mercury removal from coal-fired power plants have been investigated. However, more effort is needed to achieve an efficient and cost-effective technology. The main objective of this work is to investigate the influence of scrubber parameters on mercury removal efficiency to establish effective measures for mercury control. In order to attain these objectives, theoretical predictions based on thermodynamical equilibrium data and lab-scale experimental tests were carried out. The results obtained point to pH and slurry concentration as the most critical parameters for converting FGD (Flue Gas Desulphurization unit) into a multipollutant control technology.