烧结矿应用于化学链燃烧的反应特性

本文通过热重实验研究了烧结矿作为载氧体的H₂还原反应特性,将其与通过溶解法制备的Fe₂O₃/Al₂O₃载氧体进行了氧化还原反应性比较,在500~1250℃范围内研究了温度对于烧结矿还原反应过程的影响,在950℃下进行了30次循环反应实验,采用四种模型进行了反应动力学分析.结果表明,烧结矿的H₂还原转化率大于80%,可以完全再氧化,并具有良好的循环反应性能.在500~950℃范围内,随温度升高还原反应速率及最终转化率都显著增加;而当温度高于1100℃时,在反应后期还原反应速率和最终转化率有下降的趋势.在500~950℃范围内,对烧结矿的还原过程第一反应阶段(Fe₂O₃-Fe₃O₄/FeO,还原转化率< 25%)可采用二阶反应模型(M2)拟合,得到表观活化能为E=36.018 kJ·mol-1,指前因子为A₀=1.053×10-2 s -1;第二反应阶段(Fe₃O₄/FeO-Fe,还原转化率> 25%)采用收缩核模型(M4)拟合,得到的表观活化能为E=51.176 kJ·mol-1,指前因子为A₀=1.066×10-2 s -1. 

Reaction characteristics of sintering ore used as an oxygen carrier in chemical looping combustion

The reduction kinetics of sintering ore used as an oxygen carrier in the chemical looping combustion was experimentally investigated by thermogravimetry. The redox reactivity of sintering ore was compared with that of self-made Fe₂O₃/Al₂O₃ oxygen carriers prepared by the dissolution method. Experiments were conducted on the reduction of sintering ore by diluted hydrogen during the temperature range of 500 to 1250℃, and 30 cycles of redox reaction experiments were performed at 950℃. Experimental data was analyzed by four kinetic models. It is found that sintering ore can be used as an oxygen carrier with a reduction conversion larger than 80%, complete oxidization, and a good performance of recyclability. The reduction reaction rate and final fractional conversion of sintering ore both increase with rising temperature from 500℃ to 950℃, while both have a trend of decline when the temperature is above 1100℃. The second order reaction model (M2) can properly fit the experimental data of the reduction of sintering ore in the first reaction stage (Fe₂O₃-Fe₃O₄/FeO, reduction conversion X < 25%) during the temperature range of 500 to 950℃, achieving the apparent activation energy E=36.018 kJ·mol-1 and the pre-exponential factor A₀=1.053×10-2 s-1, whereas the shrinking core model (M4) fits well in the second reaction stage (Fe₃O₄/FeO-Fe, reduction conversion X > 25%), achieving the apparent activation energy E=51.176 kJ·mol-1 and the pre-exponential factor A₀=1.066×10-2 s-1.