Mercury capture by an activated carbon in a fixed-bed bench-scale System

The control of mercury emissions for utility power plants may become important because of the Clean Air Act Amendments requirement that the U.S. Environmental Protection Agency (EPA) assess the health risks associated with these emissions [1]. One approach for mercury removal, which may be relatively simple to retrofit (compared to other methods [2-4]), is the injection of sorbents, such as activated carbon, upstream of existing particulate control devices. A study, sponsored by the Electric Power Research Institute (EPRI) and the U.S. Depart ment of Energy (DOE), is being conducted at the University of North Dakota Energy & Environmental Research Center (EERC) to develop a sorbent-screening test protocol, screen potential mercury sorbents in a bench-scale fixed-bed system and provide data to support efforts to model mercury capture mechanisms. A proper protocol is required to establish repeatability of the results and ensure reproducibility of results between different labs. To date, elemental mercury tests have been completed with several sorbents and under various flue gas conditions. The carbon-based sorbent used in this study was a lignite-based activated carbon (LAC), commercially available from American Norit Co., Inc. This paper presents results from the more recent tests with the LAC sorbent and elemental mercury. The LAC sorbent has also been used by others as a baseline sorbent [5-7].