Transformation of alkali and alkaline-earth metals during coal oxy-fuel combustion in the presence of SO2 and H2O

Autor: Liping Chang, Liying Wang, Zengshuang Wang, Jian-Ying Lin, Meijun Wang, Haixin Mao
Rok vydání: 2015
Předmět:
Zdroj: Journal of Energy Chemistry. 24:381-387
ISSN: 2095-4956
DOI: 10.1016/j.jechem.2015.07.006
Popis: The occurrence modes of alkali and alkaline-earth metals (AAEMs) in coal relate to their release behavior and ash formation during combustion. To better understand the transformation of AAEMs, the release behavior of water-soluble, HCl-soluble, HCl-insoluble AAEMs during Shenmu coal (SM coal) oxy-fuel combustion in the presence of SO 2 and H 2 O in a drop-tube reactor was investigated through serial dissolution using H 2 O and HCl solutions. The results show that the release rates of AAEMs increase with an increase in temperature under the three atmospheres studied. The high release rates of Mg and Ca from SM coal are dependent on the high content of soluble Mg and Ca in SM coal. SO 2 inhibits the release rates of AAEMs, while H 2 O promotes them. The effects of SO 2 and H 2 O on the Na and K species are more evident than those on Mg and Ca species. All three types of AAEMs in coal can volatilize in the gas phase during coal combustion. The W-type AAEMs release excessively, whereas the release rates of I-type AAEMs are relatively lower. Different types of AAEM may interconvert through different pathways under certain conditions. Both SO 2 and H 2 O promote the transformation reactions. The effect of SO 2 was related to sulfate formation and the promotion by H 2 O occurs because of a decrease in the melting point of the solid as well as the reaction of H 2 O.
Databáze: OpenAIRE
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