The Clean Air Act Amendments of 1990 (CAAA) address 189 hazardous air pollutants (HAPs) believed to be detrimental to human health and the environment and found that mercury and its compounds are one of the highest priority pollutants to investigate. The CAAA required the U.S. Environmental Protection Agency (EPA) to conduct a mercury emissions study, including those from electric utility steam generating units. In 1997, EPA released the Mercury Study Report to Congress which analyzed mercury emissions from power plants and investigated control technologies. In 1998, EPA released the Utility Air Toxics Study which also showed mercury as a top priority pollutant due to its multi-pathway exposure potential and its ability to bio-accumulate and persist in the environment as methyl mercury. [1, 2]
Mercury control in combustion flue gas is highly dependent on speciation. Oxidized mercury is removed relatively easily by particulate control equipment as well as wet scrubbers used to control sulfur dioxide. However, elemental mercury is highly volatile and has very low water solubility allowing it to escape through most pollution control equipment. The objective of this project is to understand the importance of and the contribution of gas-phase coal constituents in the mercury oxidation reactions. The project involves experimental efforts. The objective is to determine the experimental parameters of importance in the homogeneous oxidation reactions; effect of each of these parameters on the mercury oxidation for various concentration and temperatures. The objective of this project was to test the performance of Bromine and Chlorine (Cl2) on homogeneous mercury oxidation in the presence of common flue gas components such as Nitric Oxide and Sulfur Dioxide and water vapor. This parametric testing was performed using a bench-scale system and simulated flue gas.
Chapter 2 of this thesis discusses the background of mercury chemistry, regulation, and control technologies. Chapter 3 explains the experimental equipment and methods used for bench-scale simulated flue gas testing. Chapter 4 presents and discusses the results for both Bromine and Chlorine testing. Chapter 5 gives conclusions for this work and makes recommendations for future
Mercury is a pollutant emitted globally from natural and manmade sources circulated and deposited by various processes at widely varying rates, and subject to complex chemical transformations. For quite some time, it is known that high concentrations of mercury can be toxic to humans. The Scientific evidence has suggested that mercury emissions from human activities are having widespread impacts on environment and human health . Mercury is an immediate concern for the U.S. electric power industry because of the U.S. Environmental Protection Agency's (EPA) December 2000 decision that regulation of...