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NOVEL ECONOMICAL HG(0) OXIDATION REAGENT FOR MERCURY EMISSIONS CONTROL FROM COAL-FIRED BOILERS
LEE, J., T. C. KEENER, Y. JU, R. S. VARMA, S. K. SIKDAR, AND S. KHANG. NOVEL ECONOMICAL HG(0) OXIDATION REAGENT FOR MERCURY EMISSIONS CONTROL FROM COAL-FIRED BOILERS. Presented at AIChE 2005 Fall Meeting, Cincinnati, OH, October 30 - November 04, 2005.
To inform the public
The authors have developed a novel economical additive for elemental mercury (Hg0) removal from coal-fired boilers. The oxidation reagent was rigorously tested in a lab-scale fixed-bed column with the Norit America's FGD activated carbon (DOE's benchmark sorbent) in a typical PRB subbituminous/lignite simulated flue gas (500 ppmv SO2, 200 ppmv NO, 10 ppbv Hg0, 7% H2O, 3% O2, 12% CO2 balanced with N2) at 140 °C for sorbent injection. The test results showed excellent performance on Hg0 removal by the mixture of the additive and the activated carbon. Fixed-bed results also showed that a very small amount (~10%) of activated carbon injection could eliminate almost all of the mercury generated by reaction(s) of Hg0 with the additive, indicating promising use in subbituminous/lignite flue gases with relatively high Hg0 content. A preliminary cost estimate for sorbent injection was almost 70~80% less than that of raw FGD activated carbon at subbituminous and lignite-firing sites. The additive is thermally stable up to 350 °C, suggesting potential high-temperature applications for coal gasification and hot-side electrostatic precipitator. As an alternative, the oxidized mercury generated from reaction(s) with the additive could be removed in wet scrubbers due to its high solubility in water. Therefore, the additive can be applied to virtually all coal-fired power plants where Hg0 emissions are relatively high such as PRB subbituminous and/or lignite coal-firing sites as an economical and viable option.