Abstract: Chemical-looping combustion(CLC)is a promising technology with inherent separation of CO₂.Because coal is cheaper and more abundant than gaseous fuel,it is attractive to adapt CLC for use with coal.The gasification process of coal is the limiting step,so this study presented an enhancement of gasification rate of coal using Na-loaded iron ore as oxygen carrier in a 1 kW_th continuous reactor.The effect of fuel reactor temperature on the chemical-looping combustion of coal was investigated.The results showed that the catalytic effect of Na on coal gasification was obvious in the fuel reactor temperature range of 820-920℃.There was an obvious increase in the concentration of CO₂ from fuel reactor and a decrease in the concentration of CO with the increase of fuel reactor temperature.The CO₂ capture efficiency and carbon capture efficiency for Na-loaded iron ore were 78.60% and 80.54% respectively,whereas those for iron ore were 40.27% and 45.65%.The Na-loaded iron ore showed sintering and agglomeration on the oxygen carrier particles and the defluidization phenomena of the fuel reactor was observed at a fuel reactor temperature of 950℃.This was likely due to the low melting point of the sodium compounds and the over-reduction of the oxygen carrier.SEM and XRD analysis showed that the reduction degree of Fe₂O₃ in the oxygen carrier using Na-loaded iron ore was intensively enhanced.

Key words: coal combustion, catalysis, carbon dioxide, iron ore, chemical-looping combustion

摘要： 利用1 kW_th串行流化床反应器对钠修饰铁矿石载氧体进行试验研究,考察燃料反应器温度对煤化学链催化燃烧特性的影响。结果表明,钠在820～920℃温度下显著促进了煤气化反应的进行,随着燃料反应器温度的提高,使用Na-铁矿石时燃料反应器出口CO₂浓度明显增大,CO浓度明显降低,在920℃时CO₂捕集效率和碳捕集效率分别达到78.60%和80.54%,而使用纯铁矿石时CO₂捕集效率和碳捕集效率仅为40.27%和45.65%。在高温950℃时Na-铁矿石活性下降,出现烧结和团聚现象,燃料反应器出现滞流态化现象,这可能是钠的化合物熔点较低和载氧体过度还原所导致的。XRD和SEM分析结果显示钠修饰铁矿石促使更多的Fe₂O₃被还原为Fe₃O₄。

关键词: 煤燃烧, 催化, 二氧化碳, 铁矿石, 化学链燃烧