化学链燃烧过程中铁基烧结返矿载氧体反应活性及结构研究

使用流化床,以95%的甲烷作为还原性气氛,以烧结过程中烧结返矿作为载氧体,研究其在化学链燃烧过程中的反应活性以及烧结返矿在氧化还原循环中的结构特征。对烧结矿原料、还原后以及氧化再生的烧结矿进行形貌结构及物性表征。结果表明,在初始氧化循环过程中,烧结返矿的载氧能力和反应活性有显著的提高;前25个循环过程中,烧结返矿的比表面积显著增大,比表面积的增大是提高烧结返矿反应活性的主要原因之一。随着循环的进行,烧结返矿表面出现裂纹并逐渐加大。Raman检测结果显示,在还原过程中有新的铁晶型,纤铁矿(γ-Fe OOH)生成,而纤铁矿(γ-Fe OOH)的生成将降低烧结返矿的载氧能力。氧化循环过程中,采用甲烷作为还原性气体,并未发现有碳沉积现象的产生。

Reaction activity and structural characterizations of sintered return fine oxyen carriers in chemical-looping combustion

The reactivity and structural characterizations of the sintered iron ore in redox cycles were investigated. The sintered return fines were selected as oxygen carriers and the chemical looping combustion was tested in a fluidized bed with a reducing atmosphere of 95% methane. The characterizations of structural and physical properties of the sintered raw materials and the reduced and oxidative regenerated samples were conducted. The results reveal that during the initial oxidation cycle, the oxygen carrying capacity and reaction activity of the sinter are improved remarkably. The specific surface area of the sinter increases significantly in the first 25 cycles, which may be one of the main reasons for the reactivity increase of the sinter. During the recycling process, some cracks are formed on the surface of sintered return fines and gradually get development. The Raman results indicate that the new crystalline phase, lepidocrocite (γ-FeOOH), is formed, which will decrease the oxygen carrying capacity of the oxygen carrier. When the methane is used as the reducing gas, there is no carbon deposition on the surface.