基于钾基修饰铁矿石载氧体的煤化学链燃烧循环实验

对天然的铁矿石加以钾基修饰,在流化床上进行了煤化学链燃烧循环实验。研究了改性后的铁矿石对气体产物浓度及含碳气体体积分数影响的持续力。钾基铁矿石缩短了反应时间并明显提高了CO₂浓度;在20次循环中,钾基铁矿石能明显提高CO₂体积分数并降低CO体积分数,11次循环后,CO₂体积分数稍有减少,CO体积分数略有增加。借助于扫描电镜与电子能谱(SEM-EDX)和X射线衍射(XRD),对不同循环后的载氧体进行表征。与纯铁矿石相比,前10次循环钾基铁矿石载氧体表面严重烧结,20次循环之后烧结减轻,恢复多孔结构。结果表明,钾基铁矿石载氧体中KFe₁₁O₁₇或其衍生物对煤气化有催化作用;在20次循环中存在钾流失现象;20次循环后钾基铁矿石载氧体能完全氧化为Fe₂O₃。

Cycle experiments on chemical looping combustion of coal using potassium-improved iron ore as oxygen carrier

The cycle experiments on chemical looping combustion of coal were carried out in a fluidized bed using a K-promoted iron ore as oxygen carrier. The continued effect of the K-promoted iron ore on the gas compositions, fractions of carbonaceous gases was investigated.The results showed that the reaction time was shortened by the K-promoted iron ore,and that the CO₂ concentration was significantly increased.The CO₂ fraction for the K-promoted iron ore was much higher than that for the iron ore whereas,the CO fraction was much lower during 20 cycles.After 11 cycles, the CO₂ fraction slightly decreased with a slight increase in CO fraction for the K-promoted iron ore. The reduced oxygen carriers after different cycles were characterized by SEM-EDS (Scanning Electron Microscope-Energy Dispersive Spectrometer) and XRD (X-ray diffraction).Compared with pure iron ore, the K-promoted iron ore showed serious sinter on the oxygen carrier particles during the first 11 cycles. The oxygen carrier, however, re-obtained the porous structure after 20 cycles due to the loss of potassium.The XRD showed that the KFe₁₁O₁₇ or its derivatives displayed the catalytic effect on coal gasification in the process of chemical looping combustion and the oxygen carrier could be regenerated to Fe₂O₃ after 20 cycles.