Coal Chemical Looping Gasification for Syngas Generation Using an Iron-Based Oxygen Carrier

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• 作者：Qingjie Guo ; Yu Cheng ; Yongzhuo Liu ; Weihua Jia ; Ho-Jung Ryu
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：January 8, 2014
• 年：2014
• 卷：53
• 期：1
• 页码：78-86
• 全文大小：476K
• ISSN：1520-5045

文摘

The chemical-looping gasification (CLG) of coal is a clean and effective technology for syngas generation. Sharing principles with chemical-looping combustion (CLC), CLG also uses oxygen carriers to transfer lattice oxygen to the fuel. Investigations into CLG with different O/C ratios are carried out in a fluidized bed reactor with steam used as the gasification鈥揻luidization medium. The effect of the active component content of the oxygen carrier on the gas selectivity is performed, and reaction mechanisms between the Fe₂O₃ oxygen carrier and coal with steam as the gasification agent are discussed. Moreover, we also assessed the reactivity of the CaO-decorated iron-based oxygen carrier particles in multicycle reactions. The carbon conversion efficiency is increased from 55.74 to 81% with increasing O/C ratio, whereas the content of H₂ first decreases and then increases. The addition of CaO can increase the carbon conversion efficiency and the gasification rate substantially and reduce the generation rate of H₂S from 1.89 脳 10^鈥? to 0.156 脳 10^鈥? min^鈥?. Furthermore, X-ray diffraction (XRD) images indicate that the CaO-decorated iron-based oxygen carrier particles were completely regenerated after six redox cycles. Finally, the peak fitting of gasification reaction rate curves is used to explore the reaction mechanism between coal char and the CaO-decorated iron-based oxygen carrier, indicating that the reactions in the CLG include three stages: the complex reactions involved an oxygen carrier, coal char, and steam; the gasification of coal char; and the reduction of Fe₃O₄ to FeO. The two-segment modified random pore model (MRPM) fits the experiment data well.