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Received December 25, 2002,Revised March 20, 2003, Accepted , Available online

Volume 16,2004,Pages 242-246

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The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and flyash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements wereinvestigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. Onecoefficient of Meij was also improved to more directly show element enrichment in combustion products. Theseelements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile.Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be locatedbetween groups 1 and 2. Cr has properties of both group 1 and 3. In addition, the smaller diameter of fly ash, themore relative enrichment of trace elements( except Mn). The fly ash showed different adsorption mechanisms oftrace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of traceelements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not alwaysimprove the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Traceelements should be classified in accordance with factors.

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