褐煤在合成气气氛下的低温热解及半焦燃烧特性

Low temperature pyrolysis of lignite in the presence of syngas and combustion characteristics of derived char

在固定床反应器中进行了3种褐煤在惰性及合成气气氛下的热解实验,研究了不同气氛下褐煤热解的产物分布及产物性质(包括气体组成,半焦性质等),并对所得半焦的燃烧特性进行了对比.结果表明,与惰性气氛下相比,褐煤在合成气气氛下热解时焦油收率提高1.5%～1.9%.合成气气氛下热解时,热解气中的H2S和COS含量明显比惰性气氛下升高,表明合成气气氛对褐煤热解有较好的脱硫效果.合成气气氛下所得热解半焦的氧含量要低于惰性气氛下的,表明合成气对褐煤热解脱氧有较好的效果.两种气氛下所得热解半焦的着火点、最大燃烧温度和燃尽温度比原煤略有升高,合成气下热解半焦的特征燃烧温度的提高程度较惰性气氛下的小.合成气中的CO能够与煤热解产生的水发生水煤气变换反应产生高活性的氢,抑制了交联反应,提高了油气收率.

Lignite pyrolysis under syngas and inert gas at low temperature was conducted in a fixed-bed reactor.The product distribution under different atmospheres and the characteristics of the products including gas composition and the char analyses were investigated in this work.The combustion characteristics of the char obtained at different conditions were also studied and compared.The results show that the oil yield under syngas is higher than that under inert gas by 1.5%-1.9%.The contents of H2S and COS in the gas product during pyrolysis under syngas is higher than that under inert gas,which show that syngas has a better ability in desulphurization of lignite during pyrolysis.Additionally,the oxygen of the char obtained under syngas is lower than that of under inert gas,showing that the syngas beneficial in the de-oxygenating of the lignite.The ignition temperature,peak temperature of maximum weight loss rate and burnout temperature of the chars obtained under the two atmosphere are all a little higher than that of the raw lignite,however,the increment of the three specific temperatures of the chars obtained under syngas are lower than those of under inert gas.CO in syngas can react with water produced during lignite pyrolysis to produce hydrogen with high activity,which can suppress the cross-linking reactions during pyrolysis and enhance the yields of oil and gas.