Release Rules of Alkali and Alkaline Earth Metals during Coal Combustion under Different Atmosphere in a Fixed Bed Reactor

The concentrations of CO2,SO2 and H2O in the furnace during oxy-fuel combustion are higher than those of air combustion,and this may influence the combustion characteristics and transformation of inherent substances in coal.The release of alkali and alkaline earth metals during combustion under different atmosphere was investigated by using fixed bed reactor and ion chromatography in this paper.The results indicate that the release rates of Na and K were higher than those of Mg and Ca.The release rules of Na and K were influenced by atmosphere markedly.The release rates of Na and K decreased slightly during oxy-fuel combustion owing to the carbonation reactions of K and Na in the presence of CO2.The existance of SO2 and H2O enhanced the combustion reactivity of coal,and the release rates of Na and K increased.The release rates of Mg and Ca were quite lower because of their stable properties,and the effect of atmosphere on the release rates of Mg and Ca was also not obvious.