水泥改性铁矿石载氧体的煤化学链燃烧实验研究

Experiments on Chemical-looping Combustion of Coal With Cement-Decorated Iron Ore as Oxygen Carrier

对天然铁矿石混合水泥进行改性,在流化床上进行了煤化学链燃烧试验研究,考察改性后载氧体的氧化还原反应性能。结果表明,水泥能够有效地促进水气变换反应的进行,使得煤气化产物中CO份额减小、H2份额增大。改性后载氧体比表面积和孔容积显著增大,反应活性得到提高,燃料反应器出口气体中仅存在微量CO、H2,其浓度远低于纯铁矿石为载氧体的实验结果。在20次循环试验中,水泥改性铁矿石能大幅提高CO2体积份额;对不同循环后载氧体的扫描电镜表征显示,水泥能够有效阻止载氧体颗粒表面的晶粒在高温下的液相接触,降低载氧体颗粒氧化再生过程中单位体积的热量释放强度,缓解烧结现象的发生,维持载氧体颗粒多孔的结构特性。

Experiments on chemical looping combustion of coal were conducted in a fluidized bed using cement-decorated iron ore as oxygen carrier.The reactivity of the oxygen carrier during redox experiments was investigated.The results indicate that the addition of cement effectively promotes the water-gas shift reaction,leading to the decrease of CO fraction and the increase of H2 fraction in coal gasification products.After decorated the oxygen carrier gets its specific surface area and pore volume increased significantly,and reactivity improved as a result.Further,the concentrations of CO and H2 in the flue gas of the fuel reactor are far lower than that of the experiments for pure iron ore.The volume fractions of CO2 for cement-decorated iron ore increase greatly during 20 cycles.Characterization of reduced oxygen carrier with scanning electron microscope（SEM） indicates that cement can prevent the surface grains of the oxygen carrier from gathering in the liquid phase under high temperature,and reduce the heat density released in a unit volume of the oxygen carrier particle in the oxidization process,thus alleviating the sintering and keeping the oxygen carrier porous.