Zhao Shilin, Duan Yufeng, Chen Lei, Li Yaning, Yao Ting, Liu Shuai, Liu Meng, Lu Jianhong
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China.
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China; Hua Neng Nantong Power Plant, Nantong, 226003, China.
Environ Pollut. 2017 Oct;229:863-870. doi: 10.1016/j.envpol.2017.07.043. Epub 2017 Aug 2.
Hazardous trace elements (HTEs), especially mercury, emitted from coal-fired power plants had caused widespread concern worldwide. Field test on mercury emissions at three different loads (100%, 85%, 68% output) using different types of coal was conducted in a 350 MW pulverized coal combustion power plant equipped with selective catalytic reduction (SCR), electrostatic precipitator and fabric filter (ESP + FF), and wet flue gas desulfurization (WFGD). The Ontario Hydro Method was used for simultaneous flue gas mercury sampling for mercury at the inlet and outlet of each of the air pollutant control device (APCD). Results showed that mercury mass balance rates of the system or each APCD were in the range of 70%-130%. Mercury was mainly distributed in the flue gas, followed by ESP + FF ash, WFGD wastewater, and slag. Oxidized mercury (Hg) was the main form of mercury form in the flue gas emitted to the atmosphere, which accounted for 57.64%-61.87% of total mercury. SCR was favorable for elemental mercury (Hg) removal, with oxidation efficiency of 50.13%-67.68%. ESP + FF had high particle-bound mercury (Hg) capture efficiency, at 99.95%-99.97%. Overall removal efficiency of mercury by the existing APCDs was 58.78%-73.32%. Addition of halogens or oxidants for Hg conversion, and inhibitors for Hg re-emission, plus the installation of a wet electrostatic precipitator (WESP) was a good way to improve the overall removal efficiency of mercury in the power plants. Mercury emission factor determined in this study was from 0.92 to 1.17 g/10J. Mercury concentration in the emitted flue gas was much less than the regulatory limit of 30 μg/m. Contamination of mercury in desulfurization wastewater should be given enough focus.
燃煤电厂排放的有害微量元素（HTEs），尤其是汞，已引起全球广泛关注。在一座配备选择性催化还原（SCR）、静电除尘器和布袋除尘器（ESP + FF）以及湿法烟气脱硫（WFGD）的350兆瓦煤粉燃烧电厂，针对三种不同负荷（100%、85%、68%出力）使用不同类型煤炭的汞排放情况进行了现场测试。采用安大略省水电法对各空气污染物控制装置（APCD）进出口的汞进行同步烟气汞采样。结果表明，系统或各APCD的汞质量平衡率在70% - 130%范围内。汞主要分布在烟气中，其次是ESP + FF灰、WFGD废水和炉渣。氧化汞（Hg）是排放到大气的烟气中汞的主要形态，占总汞的57.64% - 61.87%。SCR有利于单质汞（Hg）的脱除，氧化效率为50.13% - 67.68%。ESP + FF对颗粒态汞（Hg）的捕集效率很高，为99.95% - 99.97%。现有APCD对汞的总体脱除效率为58.78% - 73.32%。添加卤素或氧化剂促进汞转化以及汞再排放抑制剂，再加上安装湿式静电除尘器（WESP）是提高电厂汞总体脱除效率的良好方法。本研究确定的汞排放因子为0.92至1.17克/10吉焦。排放烟气中的汞浓度远低于30微克/立方米的监管限值。脱硫废水中汞的污染问题应予以足够重视。
