Mercury Speciation and Distribution in a Coal-Fired Power Plant

• Main Authors: Hui Min, 尉慧敏
• Other Authors: Jim Juimin Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/14809285865479448467

碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 99 === This study examined the mercury (Hg) distribution, mass balance, and the removal effectiveness of the air pollution control devices (APCDs) in a local coal-fired power plant. The sampling results showed that the major source of Hg in the tested coal-fired power plant was coal (97.8%); only a small amount of Hg contributed by the limestone (2.2%). The major output of Hg was attributed to fly ash (53.3%), followed by the flue exhaust (24.0%) and gypsum as well as raw wastewater (22.7%). The overall mass balance disclosure was calculated to be approximately 85.4%. The Hg emissions from stack into the atmosphere was 0.601 μg/Nm3 in average, Hg0 , Hg2+, and Hgp occupied 91.3%, 7.4%, and 1.3%, respectively. The distribution and speciation of Hg were strongly affected by the APCDs, in particular, electrostatic precipitator (ESP) and flue gas desulfurization process (FGD) in this case. The average Hg concentration of coals was measured to be 0.036 mg/kg, showing that the Hg content in the coals used by the coal-fired power plant was relatively low. The average total Hg removal was about 76 %, consistent with the results reported by Meij et al. (2002) and the USEPA (i.e., between 29 and 74%). These analytical results suggested that the APCDs installed in the tested plant had a good performance in Hg removal. However, this 76% Hg removal can not achieve the goal set by the USEPA in March 16, 2011, in which 91% Hg removal should be achieved. As a consequence, two improvement strategies were proposed and further discussed in the present works.