Experimental Study On Removal Mercury From Flue Gas By Aqueous Solution

The experimental study on removal of Hg0 from flue gas is carried out in bench-scale bubbling reactor in this paper. A type of absorbents, namely sodium chlorite, with known overall superior performance is selected in a bubbling reactor. Effect of sodium chlorite concentration, the initial pH value of absorbing solution, mercury concentration in the inlet of reactor, reaction temperature, and the concentration of SO₂, NO is investigated. The results show that the pH value has a significant impact on the removal efficiency. The efficiency is greater in acidic than neutral solutions and alkaline, which can attain above 90%. The addition of NO in flue gas significantly improves the mercury removal efficiency, when NaClO₂ solution provides enough. Increasing the concentration of SO₂, the removal efficiency of Hg0 doesn't influence. Furthermore, the presence of SO₂ in the simulating flue gas reduces the Hg removal efficiency by about 30% from the same level without SO₂ (but with NO). The parallel experiments show that under the optimal operating conditions, the removal efficiencies of 100%, 97.8% and 76% are achieved for SO₂, NO, and Hg0 respectively. Moreover, the products are analysed by chemical analysis methods and the mechaism of removing SO₂, NO and Hg0 by aqueous sodium chlorite in bubbling reactor is discussed.