Using bromine gas to enhance mercury removal from flue gas of coal-fired power plants.
Using bromine gas to enhance mercury removal from flue gas of coal-fired power plants.
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DOI：
10.1021/es061705p
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发表时间：
2007-02
影响因子：
11.4
通讯作者：
Shou‐Heng Liu;Naiqaing Yan;Zhao Liu;Zan Qu;H. -. Wang;S. Chang;Charles Miller
中科院分区：
文献类型：
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作者：
Shou‐Heng Liu;Naiqaing Yan;Zhao Liu;Zan Qu;H. -. Wang;S. Chang;Charles Miller
对溴气体将元素汞（Hg 0）转化为氧化汞的情况进行了评估，氧化汞是一种易于被现有空气污染控制装置捕获的形式。Hg 0被Br 2气相氧化的速率随温度的升高而降低。SO2、CO、HCl和H2O对Hg 0氧化的影响不显著，而NO对Hg 0氧化的影响则相反：低浓度时促进，高浓度时抑制。提出了一个反应机制，涉及形成货车德瓦耳斯集团accountfor NO的逆效应。在模拟没有飞灰的烟道气的条件下获得的表观气相氧化速率常数在410 K下为3.61 x 10（-17）cm 3 x molecule（-1）x s（-1），对应于在15 s的反应时间内使用52 ppm Br 2进行50% Hg 0氧化。烟气中的飞灰对Hg 0被Br 2氧化有显著的促进作用，其中未燃碳组分主要通过快速吸附Br 2有效地将Hg 0从气相中去除而起到主要的促进作用。在典型的烟气温度下，SO2轻微抑制飞灰诱导的Hg 0去除。相反，NO略有促进粉煤灰诱导的Hg 0去除溴。Norit Darco-Hg-LH和Darco-Hg粉末活性炭，已在现场试验中证明，推断估计粉煤灰引起的Hg 0氧化溴。在全规模发电厂烟气中加入0.4 ppm的气态Br 2，估计约60%的Hg 0被氧化。
Bromine gas was evaluated for converting elemental mercury (Hg0) to oxidized mercury, a form that can readily be captured by the existing air pollution control device. The gas-phase oxidation rates of Hg0 by Br2 decreased with increasing temperatures. SO2, CO, HCl, and H2O had insignificant effect, while NO exhibited a reverse course of effect on the Hg0 oxidation: promotion at low NO concentrations and inhibition at high NO concentrations. A reaction mechanism involving the formation of van der Waals clusters is proposed to accountfor NO's reverse effect. The apparent gas-phase oxidation rate constant, obtained under conditions simulating a flue gas without flyash, was 3.61 x 10(-17) cm3 x molecule(-1) x s(-1) at 410 K corresponding to a 50% Hg0 oxidation using 52 ppm Br2 in a reaction time of 15 s. Flyash in flue gas significantly promoted the oxidation of Hg0 by Br2, and the unburned carbon component played a major role in the promotion primarily through the rapid adsorption of Br2 which effectively removed Hg0 from the gas phase. At a typical flue gas temperature, SO2 slightly inhibited the flyash-induced Hg0 removal. Conversely, NO slightly promoted the flyash induced Hg0 removal by Br2. Norit Darco-Hg-LH and Darco-Hg powder activated carbons, which have been demonstrated in field tests, were inferred for estimating the flyash induced Hg0 oxidation by Br2. Approximately 60% of Hg0 is estimated to be oxidized with the addition of 0.4 ppm of gaseous Br2 into full scale power plant flue gas.