Occurrence and volatility of several trace elements in pulverized coal boiler.
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.
Huang
Ya-ji
YJ
Education Ministry Key Laboratory on Clean Coal Power Generation and Combustion Technology, Southeast University, Nanjing 210096, China.
Jin
Bao-sheng
BS
Zhong
Zhao-ping
ZP
Xiao
Rui
R
Tang
Zhi-yong
ZY
Ren
Hui-feng
HF
D000327:Adsorption; D002244:Carbon / Q000032:analysis*; D003031:Coal / Q000032:analysis*; D060729:Coal Ash; D010100:Oxygen; D010316:Particle Size; D052638:Particulate Matter; D013696:Temperature; D014131:Trace Elements / Q000032:analysis*
D003031:Coal; D060729:Coal Ash; D052638:Particulate Matter; D014131:Trace Elements; D002244:Carbon; D010100:Oxygen