煤热解过程焦中硫的残留及煤中硅、铝、碳的影响

用HCl和HNO3对不同煤阶(褐煤、烟煤、无烟煤)的七种煤进行了部分矿物质的脱除处理,获得的样品主要含硅铝矿物质。通过程序升温热解和程序升温氧化两个过程,结合含碳量的差别,对煤热解过程中煤中硅铝对硫在焦中的残留状况的影响进行了研究。结果表明,脱除了其他矿物质的煤其煤化程度和硅铝比共同影响热解过程中焦中硫的残留率。焦中硫的残留率随样品含碳量增加而增加,但在煤的含碳量90%左右发生转折。这与煤的其他物理性质(如孔隙率、可磨性、质量热容、介电常数、溶剂溶胀率)类似,与煤结构在这点附近的较大变化有关。对应于各自煤阶,由于硅对气相含硫产物与半焦二次反应的抑制作用,焦中硫的残留率随着Si/Al质量比的增加而减少。

Sulfur retention in char during coal pyrolysis and influence of silicon, aluminum and carbon in coal

Seven partial demineralized coal samples （which basically contain only silicon and alumina minerals）were studied. The raw coals with different ranks were treated with HCl and HNO₃. The transformation behavior of sulfur in coals to char and the influence of silicon, aluminum and carbon were studied through a temperature programmed decomposition (TPD) and a temperature programmed oxidation (TPO) process. The results reveal that both the carbon content and the weight ratio of Si/Al affect the sulfur retention ratio in char. The retention ratio of sulfur in char increases with the increase of carbon content, but it reverses when the carbon content is around 90%. It is attributed to the significant change of the sample structure around this carbon content. For the acid treated coals from the same rank, the sulfur retention ratio in chars decreases with the increase of Si/Al weight ratio due to the inhibition effect of silicon on the secondary reaction between the gaseous sulfur-containing components and the char.