[Retention of selenium volatility using lime in coal combustion].
For understanding the volatility of selenium, the effect of the contents of exchangeable cations of coal on it, and the retention of selenium using CaO in coal combustion, the sequential chemistry extraction, the fixed bed and circulating fluidized bed (CFB) combustion, X-ray diffraction (XRD) and atomic fluorescence spectrometry (AFS) were undertaken. The results showed that the volatility of selenium was more than 97% in coal combustion at 815 degrees C, and the volatility of selenium was affected by the content of exchangeable cations of coal in low-middle temperature. It was identified that lime can restrain the volatility of selenium. In fixed bed combustion of coal, the retention rates of selenium volatility were between 11.6% and 50.7% using lime. In circulating fluidized bed combustion of coal, partitioning of selenium changed very much in ash of different size fraction between without lime and with lime. Comparing with combustion without lime, the content of selenium in ash from chimney was less than fourth times and that in leaching water from chimney decreased by two orders of magnitude using lime. Retention of selenium volatility using lime is so effective in coal combustion, especially in CFB combustion of coal.
Zhang
J
J
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. jychang63@263.net
Ren
D
D
Zhong
Q
Q
Xu
F
F
Zhang
Y
Y
Yin
J
J
D017610:Calcium Compounds / Q000494:pharmacology*; D003031:Coal; D010087:Oxides / Q000494:pharmacology*; D012643:Selenium / Q000737:chemistry*; D013696:Temperature; D014835:Volatilization; D014961:X-Ray Diffraction
D017610:Calcium Compounds; D003031:Coal; D010087:Oxides; C016538:lime; D012643:Selenium