Oxidation and Stabilization of Elemental Mercury from Coal-Fired Flue Gas by Sulfur Monobromide
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- 作者：Zan Qu ; Naiqiang Yan ; Ping Liu ; Yongfu Guo ; Jinping Jia
- 刊名：Environmental Science & Technology
- 出版年：2010
- 出版时间：May 15, 2010
- 年：2010
- 卷：44
- 期：10
- 页码：3889-3894
- 全文大小：271K
- 年卷期：v.44,no.10(May 15, 2010)
- ISSN：1520-5851
文摘
Sulfur monobromide (S2Br2) was employed as a task-specific oxidant to capture and stabilize elemental mercury from coal-fired flue gas. Its performances on the removal of Hg0 were investigated with respect to the gas-phase reaction and particle-involved reactions. It was found that the gas-phase reaction between Hg0 and S2Br2 was rapid, and the determined second-rate constant was about 1.2(±0.2) × 10−17cm3 molecules−1 s−1 at 373 K, which was about 30 times higher than that with sulfur monochloride. The pilot tests showed that the presence of fly ash in flue gas can accelerate the removal of Hg0 significantly. It was predicted that about 90% of Hg0 removal efficiency can be obtained with 0.6 ppmv S2Br2 and 30 g/m3 fly ash in flue gas, and the unburned carbon in fly ash played an important role for Hg0 removal. The fates of S2Br2 and mercury in the process were evaluated, and the product analysis and leaching tests indicated that mercuric sulfide was the main product of the converted Hg0 by the direct reaction and consequent series reactions, which is more stable and less toxic than other mercury species. Also, the surplus S2Br2 in flue gas could be captured and neutralized effectively by the alkali components in fly ash or FGD liquor, and its hydrolysis products (elemental sulfur and sulfide) were also helpful to the stabilization of mercury. The result indicated that S2Br2 is a promising oxidant for elemental mercury (Hg0) oxidation and stabilization for mercury emission control.