赤铁矿用于生物质化学链气化氧载体的反应性能

    Natural hematite oxygen carriers for chemical-looping gasification of biomass

    • 摘要: 在鼓泡流化床反应器上以Ar气为流化介质,研究了反应温度、时间对天然铁矿石氧载体的化学反应特性的影响,并对其物理性质进行了表征。试验表明,氧载体与生物质热解产物的反应性随着温度的升高而逐渐增强,气化产物中H2、CO的含量随着温度的升高而逐渐增加,CH4、CO2的含量随着温度的升高而逐渐降低;随着反应时间的增加,氧载体活性逐渐下降,合成气中热解气含量逐渐升高。铁矿石热重试验表明,在惰性氛围下(Ar),氧载体不会释放晶格氧。利用X射线衍射、扫描电子显微镜分析了反应前后氧载体颗粒的化学成分及微观形貌,分析表明,Fe2O3的还原产物主要是FeO,天然铁矿石氧载体随着温度的增加,其颗粒表面的结焦现象越明显。试验结果表明将天然铁矿石用于生物质化学链气化过程是可行的。

       

      Abstract: The feasibility of using natural hematite as an oxygen carrier in chemical-looping gasification (CLG) of biomass has been investigated. The experiments were carried out in a thermogravimetric analyzer (TGA) and in a fluidized bed reactor using argon as fluidizing gas. The reactivity of the hematite particles as a function of the reactor temperature, reaction time was discussed. TGA experiments showed that hematite can not release the lattice oxygen in inert atmosphere, however, can provide its lattice oxygen in reducing atmosphere. It was observed that the reactivity of hematite with biomass and pyrolysis intermediate products was enhanced as temperature increased. The CO and H2 concentrations increased slightly, while CO2 and CH4 concentration declined slightly with increasing temperature during biomass gasification. The reactivity of oxygen carriers was gradually decreased as the reactions proceed in the reactor due to depletion of the active oxygen in the hematite particles in a batch test. Analysis of scanning electron microscopy (SEM) shows that the hematite particles exhibited obvious agglomeration when the reaction temperature was above 850?°C. The X-ray diffraction (XRD) experiments showed that the hematite particles occurred a transformation of Fe2O3→FeO providing the oxygen element for biomass gasification reactions. The natural hematite is a promising candidate of oxygen carriers for chemical-looping gasification of biomass.

       

    /

    返回文章
    返回