合成气气氛下褐煤与生物质共液化残渣的燃烧特性

Combustion characteristics of residues from co-liquefaction of lignite and sawdust under syngas

利用热重研究了不同液化条件(溶剂、温度、气氛、水分)下褐煤与生物质共液化所得残渣的燃烧特性。通过比较共液化残渣燃烧的三个特征温度,着火点、燃烧峰温和燃尽温度,对比分析了液化条件对残渣燃烧特性的影响及其原因,同时研究了残渣燃烧的动力学。结果表明,四氢萘为溶剂所得残渣的燃烧特性好于甲苯为溶剂的;360℃下所得液化残渣燃烧反应性好于420℃下的;合成气气氛下所得液化残渣燃烧反应性好于氢气气氛下的;液化过程加入水后,所得残渣的燃烧反应性降低。不同液化条件下所得残渣的加氢程度和收率不同,使残渣具有不同的H/C原子比、比表面积和灰分,从而对残渣的燃烧特性产生影响。残渣的燃烧特性符合三段二级反应,大部分残渣三段活化能遵循"高-低-高"的变化规律。

The combustion characteristics of residues from co-liquefaction of lignite and sawdust under different operation conditions including solvent,temperature,atmosphere,and with/without water added were examined by a thermogravimetric analyzer.The effects of different liquefaction operation conditions on the combustion characteristics of the corresponding residues were investigated through comparing their characteristic parameters such as ignition temperature,peak temperature of maximum weight loss rate and burnout temperature.Based on the TG /DTG profiles,a residue combustion kinetics model was also proposed and the kinetics parameters were obtained by Coats-Redfern method.The results show that the residue with tetralin as solvent has a better combustion reactivity than the residue with toluene as solvent,and the residue from liquefaction at 360 ℃ has a better combustion reactivity than that at 420 ℃.Syngas is beneficial to the residue having higher combustion reactivity than hydrogen atmosphere.While adding water to the feedstock during liquefaction lowers the combustion reactivity of the residue compared to the case without water added.The different atomic ratios of H/C,specific surface area and ash content of the residues that arise from the different operation conditions may contribute to the different combustion characteristics of the residues.The kinetics of residue combustion could be described by a three-stage second order kinetic model.The activation energy of three stages almost follows the order of high-low-high.