Impact of calcium chloride addition on mercury transformations and control in coal flue gas
Impact of calcium chloride addition on mercury transformations and control in coal flue gas
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DOI：
10.1016/j.fuel.2007.02.016
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发表时间：
2007-10
期刊：
影响因子：
7.4
通讯作者：
Y. Zhuang;J. Thompson;C. Zygarlicke;J. Pavlish
中科院分区：
文献类型：
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作者：
Y. Zhuang;J. Thompson;C. Zygarlicke;J. Pavlish
进行了中试规模的实验，以研究加氯化钙添加剂燃烧亚烟煤时烟气中汞的转化情况。与基线烟气中单质汞占主导地位相比，氯化钙添加剂与亚烟煤共烧产生了大约50%的氧化汞，这是由于在煤烟气中形成了活性氯。汞数据表明，在富氯烟气中，汞-烟气化学反应可能在相当高的温度（约400℃）下发生。进行了现场试验，以进一步证明共烧cacl2对汞的最终归宿的影响。这些测试是在一个配备选择性催化还原（SCR）、织物过滤器（FF）和湿式洗涤器的650兆瓦亚烟煤电厂上完成的。scr - ff -湿式洗涤器系统的总体汞去除率在200-800ppm（煤基）氯添加时为75% - 96%，而基线操作时为18-32%。现场数据表明，SCR促进了汞的氧化，可能是由于活性氯的补充形成和SCR催化剂的辅助作用。因此，烟气中的大部分汞处于氧化状态，并在下游湿式洗涤器中被去除，这表明对于配备SCR和湿式洗涤器的亚烟煤电厂来说，共烧cacl2是一种有效的汞控制方法。
Pilot-scale experiments were conducted to investigate mercury transformations in coal flue gas when firing subbituminous coal with a CaCl2additive. Cofiring the CaCl2additive with the subbituminous coal resulted in approximately 50% oxidized mercury, as a result of reactive chlorine species formed in coal flue gas, compared to the dominance of elemental mercury in the baseline flue gas. The mercury data indicate that mercury-flue gas chemistry reactions may occur at fairly high temperatures (>400°C) in chlorine-enriched flue gas. Field tests were conducted to further demonstrate the impact of cofiring CaCl2on the eventual fate of mercury. These tests were completed on a 650-MW subbituminous coal-fired power plant equipped with selective catalytic reduction (SCR), a fabric filter (FF), and a wet scrubber. Overall mercury removals across the SCR-FF-wet scrubber system ranged from 75% to 96% with 200–800ppm (coal basis) chlorine addition compared to 18–32% during baseline operations. Field data indicate that the SCR enhanced mercury oxidation, possibly as a result of the supplemental formation of reactive chlorine species and the aid of the SCR catalyst. As a result, most of the mercury in the flue gas was in an oxidized state and was removed in the downstream wet scrubber, indicating that cofiring CaCl2is an effective mercury control approach for a subbituminous coal-fired plant equipped with an SCR and wet scrubber.