Liu Qiuqi, Liu Dunyu, Ni Mingguo, Xu Kailong, Ma Jingjing, Liu Zhuang, Jin Jing, Shi Huancong
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
ACS Omega. 2022 Jun 6;7(24):20959-20967. doi: 10.1021/acsomega.2c01709. eCollection 2022 Jun 21.
Mercury emission is an important issue during chemical looping combustion (CLC) of coal. The aim of this work is to explore the effects of different flue gas components (e.g., HCl, NO, SO, and CO) on mercury transformation in the flue gas cooling process. A two-stage simulation method is used to reveal the reaction mechanism of these gases affecting elemental mercury (Hg) oxidation. Furthermore, using this method, Hg oxidation by eight oxygen carriers (CoO, CaSO, CeO, FeO, AlO, MnO, SiO, and CuO) commonly used in CLC are investigated and their Hg oxidation efficiencies were compared with the existing experimental results. The results show that HCl, NO, and CO promote Hg oxidation during flue gas cooling, while SO inhibits Hg oxidation. The stronger the oxygen release capacity of oxygen carriers, the higher the oxidation efficiency of Hg becomes. The order of Hg removal efficiency from high to low is CoO, CuO, MnO, CaSO, FeO, CeO, AlO, and SiO, and this sequence is in good agreement with the existing experimental results. Different flue gas components directly or indirectly affect the O content, thus affecting the content of gaseous oxidized mercury (Hg). Different oxygen carriers have different oxygen release capacities and different Hg oxidation efficiencies. Therefore, O is the core species affecting the mercury transformation in CLC.
汞排放是煤化学链燃烧（CLC）过程中的一个重要问题。本工作的目的是探讨不同烟气成分（如HCl、NO、SO和CO）在烟气冷却过程中对汞转化的影响。采用两阶段模拟方法揭示这些气体影响元素汞（Hg）氧化的反应机理。此外，利用该方法研究了CLC中常用的八种氧载体（CoO、CaSO、CeO、FeO、AlO、MnO、SiO和CuO）对Hg的氧化作用，并将它们的Hg氧化效率与现有的实验结果进行了比较。结果表明，HCl、NO和CO在烟气冷却过程中促进Hg氧化，而SO抑制Hg氧化。氧载体的氧释放能力越强，Hg的氧化效率越高。Hg脱除效率从高到低的顺序为CoO、CuO、MnO、CaSO、FeO、CeO、AlO和SiO，这一顺序与现有的实验结果吻合良好。不同的烟气成分直接或间接影响O含量，进而影响气态氧化汞（Hg）的含量。不同的氧载体具有不同的氧释放能力和不同的Hg氧化效率。因此，O是影响CLC中汞转化的核心物种。
