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Frontiers in Energy

Front. Energy    2007, Vol. 1 Issue (3) : 273-279
Preliminary study of trace element emissions and control during coal combustion
ZHANG Junying, ZHAO Yongchun, DING Feng, ZENG Hancai, ZHENG Chuguang
State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China;
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Abstract Hazardous trace element emissions have caused serious harm to human health in China. Several typical high-toxic trace element coals were collected from different districts and were used to investigate the emission characteristics of toxic trace elements (As, Se, Cr, Hg) and to explore preliminary control methods. Coal combustion tests were conducted in several bench-scale furnaces including drop tube furnace (DTF), circulating fluidized bed (CFB) combustion furnace, and fixed-bed combustion furnace. Calcium oxide was used to control the emission of arsenic and selenium. The granular activated carbons (AC) and activated-carbon fibers (ACF) were used to remove mercury in the flue gas from coal combustion. The chemical composition and trace element contents of ash and particulate matter (PM) were determined by X-ray fluorescence (XRF) spectrometry and inductively coupled plasma-atomic emission spectrometry (ICP-AES), respectively. The speciation and concentration of mercury were investigated using the Ontario-Hydro method. X-ray diffraction spectrometry (XRD) was used to determine the mineral composition of production during combustion experiments. With the addition of a calcium-based sorbent, arsenic concentration in PM1 sharply decreased from 0.25–0.11 mg/m3. In fixed-bed combustion of coal, the retention rates of selenium volatiles were between 11.6% and 50.7% using lime. In the circulating fluidized-bed combustion of coal, the content of selenium in ash from the chimney was reduced to one-fourth of its original value and that in leaching water from the chimney decreased by two orders of magnitude using lime. Calcium-based sorbent is an effective additive to control the emission of As and Se during coal combustion. The emission of chromium is influenced by the occurrence mode of Cr in coal. Chromium emission in PM2.5 during coal combustion is 55.5 and 34.7 μg/m3 for Shenbei coal and mixed Pingdingshan coal, respectively. The adsorptive capacity of granular activated carbon for Hg0 is significantly enhanced through ZnCl2-impregnation. The activated carbon fibers showed decent efficiency in mercury adsorption, on which surface oxygen complex showed positive effects on mercury adsorption.
Issue Date: 05 September 2007
 Cite this article:   
ZHANG Junying,ZHAO Yongchun,DING Feng, et al. Preliminary study of trace element emissions and control during coal combustion[J]. Front. Energy, 2007, 1(3): 273-279.
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ZHANG Junying
ZHAO Yongchun
ZENG Hancai
ZHENG Chuguang
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