IMPACT OF FLUE GAS CONSTITUENTS ON CARBON SORBENTS

摘要

Many of the attempts at using sorbents to control mercury from coal combustion have met with limited success for unexplained reasons. Previous results at the Energy & Environmental Research Center identified a major interaction between SO_2, NO_2, and H_2O that may be responsible for the poor sorbent performance observed in many tests (Miller, S.J.; Dunham, G.E.; Olson, E.S.; Brown T.D. Mercury Sorbent Development for Coal-Fired Boilers. In Air Qualiry: Mercury, Trace Elements, and Paniculate Matter, Special Issue of Fuel Process. Technol. 2000, 65-66). Results indicated that a combination of SO_2, NO_2, and H_2O will lead to rapid breakthrough of oxidized mercury species. Tests were conducted with leached carbon samples and carbonized aerogel samples to investigate the role of inorganic material in capture and oxidation of elemental mercury in a simulated flue gas. The results indicate the inorganic material in an activated carbon plays no role in the capture or oxidation of elemental mercury. A better understanding of how various flue gas constituents affect mercury control will be critical to the development of effective sorbents. This paper also presents a proposed model for the capture and oxidation of elemental mercury with carbon sorbents in a simulated flue gas stream.