草木灰水溶液改性的天然贫铁矿载氧体的反应性能

Experimental study on plant-ash-water modified lean iron ore oxygen carrier in chemical looping combustion

化学链燃烧是一种基于CO_2零排放理念的无焰燃烧技术,能够提高CO_2捕集效率。本文选用一种天然贫铁矿作为载氧体,在热重分析仪上采用CO作为还原气考察了其反应特性。为了减轻载氧体表面的烧结情况,本文提出了采用草木灰水溶液对天然贫铁矿载氧体进行改性,并对改性后载氧体进行短时间、多次数氧化还原循环实验研究;考察了反应器温度对改性前后的载氧体反应特性影响。实验结果表明:天然贫铁矿在15次氧化还原循环反应中展现了一定的循环稳定性,但载氧体的还原程度和反应速率较低;改性后的载氧体还原程度更深、反应速率更快,且保持了良好的反应活性。载氧体在100次的氧化还原循环中出现粉化团聚现象,导致轻微的质量损失。XRD和SEM的分析结果表明生物质灰中的K元素在反应中与铁矿石中的物质生成了新的化合物,增大了载氧体的比表面积,提高了载氧体的还原反应活性。载氧体表面没有出现明显的烧结团聚现象。

Chemical looping combustion is a new combustion mode with zero CO2emission,which can improve the efficiency of the CO2capture.A lean iron ore was employed as the oxygen carrier in this study.The CO was selected as the reducing gas.The plant-ash aqueous water was used to modify the lean iron ore.A series of chemical-looping combustion(CLC)tests were conducted in a thermogravimetric analysis reactor.The CO aeration time was reduced to60seconds.Consecutive reduction-oxidation cycles were first carried out in the TGA at various temperatures.The results indicated that the reduction reactivity of lean iron ore remained stable in15cycles.The cyclic stability of the modified oxygen carrier remained well in100cycles.The reduction condition and the chemical reaction rate of the modified oxygen carrier were better than those of the lean iron ore.The analysis of the XRD and SEM experiments showed the alkali mental K abundant in the plant ash combined with the contents of the lean iron ore through complicated reactions,which resulted in the expansion of the specific surface area of the modified oxygen carrier.The reduction reactivity of the modified oxygen carrier was enhanced without serious sintering on the surface.