Abstract This study presents the results obtained from a lab-scale two-stage reactor system to investigate the reaction characteristics and chemical kinetics of separated-gasification chemical looping combustion (SG-CLC) with a coal char as the fuel. The results have shown that there is huge mismatch of reaction rate between the slow gasification of char occurred in the gasification reactor (GR) and the rapid redox reactions of oxygen carrier (OC) and gasification products occurred in the reduction reactor (RR). Hence, the GR is recommended to be operated over 950 °C for a carbon conversion higher than 90% at the reaction time of 15 min, while 900 °C should be enough for the RR with an ideal gas combustion efficiency (>99%). Besides, the OC in SG-CLC shows favorable cycle stability, which can be attributed to the indirect mixing between the OC and char so that the attachment of potassium salt from the ash to the OC surface can be effectively avoided. In addition, the reaction kinetics models are determined to obtain the kinetics parameters of the char-fueled SG-CLC. The apparent activation energy is found to be 154.44, 149.79 and 161.42 kJ/mol for the first-order Kinetics Model, 2-D Contraction Model, and 3-D Contraction Model, respectively.

中文翻译：

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以铁矿石为氧载体的炭分离气化化学链燃烧实验及动力学研究

摘要 本研究展示了从实验室规模的两级反应器系统获得的结果，以研究以煤焦为燃料的分离气化化学循环燃烧 (SG-CLC) 的反应特性和化学动力学。结果表明，在气化反应器（GR）中发生的炭缓慢气化与在还原反应器（RR）中发生的氧载体（OC）和气化产物的快速氧化还原反应之间存在巨大的反应速率失配。因此，建议 GR 在 950 °C 以上运行，以在 15 分钟的反应时间内获得高于 90% 的碳转化率，而 900 °C 对具有理想气体燃烧效率（> 99%）的 RR 来说应该足够了. 此外，SG-CLC 中的 OC 显示出良好的循环稳定性，这可以归因于 OC 和炭之间的间接混合，从而可以有效避免钾盐从灰烬中附着到 OC 表面。此外，确定反应动力学模型以获得以炭为燃料的 SG-CLC 的动力学参数。一阶动力学模型、2-D 收缩模型和 3-D 收缩模型的表观活化能分别为 154.44、149.79 和 161.42 kJ/mol。