New method for oxidation of gaseous, elemental mercury

摘要

Elemental mercury (Hg) is difficult to remove from flue-gas streams using211u001eexisting wet-scrubber technology, primarily because of its limited volubility in 211u001ewater. We have proposed and tested a concept for enhancing gaseous Hg(sup 211u001e0)removal in wet scrubber systems by altering the chemical form of the Hg(sup 0) 211u001eto a water-soluble oxidized species. Recently, we have discovered a new method 211u001efor injection of the oxidizing species that dramatically improves reactant 211u001eutilization and at the same time gives significant nitric oxide (NO) oxidation as 211u001ewell. Our method uses a diluted oxidizing solution containing chloric acid and 211u001esodium chlorate (sold commercially as NOXSORB(trademark)). When this solution is 211u001einjected into a gas stream containing Hg(sup 0) at about 300 F, we found that 211u001enearly 100% of the Hg(sup 0) was removed from the gas phase and was recovered in 211u001eliquid samples from the test system. At the same time, approximately 80% of the 211u001eadded NO was also removed (oxidized). The effect of sulfur dioxide (SO(sub 2)) on 211u001ethis method was also investigated, and it appears to decrease slightly the amount 211u001eof Hg oxidized. We are currently testing the effect of variations in oxidizing 211u001esolution concentration, SO(sub 2) concentration, NO concentration, and reaction 211u001etime (residence time).