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Effects of NH 4 Br additive on mercury transformation and removal during CFB coal combustion
Author(s) -
Zhao Shilin,
Duan Yufeng,
Zhou Qiang,
Zhu Chun,
Liu Meng,
Lu Jianhong
Publication year - 2017
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5017
Subject(s) - mercury (programming language) , chemistry , flue gas , bromine , coal combustion products , coal , combustion , environmental chemistry , halogen , inorganic chemistry , organic chemistry , alkyl , computer science , programming language
BACKGROUND Mercury emission from coal‐fired power plants has caused widespread concern. Halogen is considered to be a good mercury oxidant and many researchers have added it into the coal for mercury removal. However, the mechanism of mercury transformation is still not clear. Effects of NH 4 Br additive on mercury transformation and removal were studied on a 6 kW th circulating fluidized bed (CFB) coal combustor. The main goal of this work is to explore in detail the mercury transformation mechanism in the presence of bromine. RESULTS Results showed that the concentration of Hg 0 and Hg 2+ in the flue gas was 2.003 and 2.434 µg m −3 , respectively, while Hg p was 14.866 µg m −3 during the raw coal combustion. By adding more NH 4 Br, the content of Hg 0 and Hg 2+ decreased while the content of Hg p increased. At an NH 4 Br addition amount of 0.3%, Hg 0 transformation rate and Hg g removal rate reached maximum values of 78.85% and 76.83%, respectively. Some mercury compounds (such as HgS(red), HgO, HgSO 3 ) were further oxidized by active bromine with NH 4 Br addition. CONCLUSION The added NH 4 Br generates active bromine in the furnace, which promotes both homogeneous and heterogeneous oxidation of mercury. Adding NH 4 Br into coal benefits mercury removal during coal combustion. © 2016 Society of Chemical Industry