Affiliations: Education Ministry Key Laboratory on Clean Coal Power
Generation and Combustion Technology, Southeast University, Nanjing 210096,
China | Thermoelectric Power Plant of Yangzi Petrochemical
Co., Nanjing 210002, China
Abstract: The contents of eight trace elements (Mn, Cr, Pb, As, Se, Zn, Cd, Hg)
in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal
boiler. Factors affecting distribution of trace elements were investigated,
including fly ash diameter, furnace temperature, oxygen content and trace
elements' characters. One coefficient of Meij was also improved to more directly
show element enrichment in combustion products. These elements 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 located between groups 1 and 2. Cr has properties
of both group 1 and 3. In addition, the smaller diameter of fly ash, the more
relative enrichment of trace elements (except Mn). The fly ash showed different
adsorption mechanisms of trace elements and the volatilization of trace elements
rises with furnace temperature. Relative enrichments of trace elements (except Mn
and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can
not always improve the volatilization of trace elements. Pb is easier to form
chloride than Cd during coal combustion. Trace elements should be classified in
accordance with factors.
Keywords: occurrence, volatility, relative enrichment, trace element, group of elements
