采用冷冻成粒法、喷雾干燥法、浸渍法、机械混合法批量制备了Fe2O3/Al2O3氧载体,从氧载体产率、制备周期、物理化学表征、煤化学链燃烧中氧载体性能等角度比较各种批量制备方法,确定合适的批量制备技术。实验结果表明,冷冻成粒法的氧载体产率较高,机械性能最优;与褐煤的化学链燃烧实验中,喷雾干燥法和冷冻成粒法制备的氧载体导致碳转化速率较快,然后依次为浸渍法和机械混合法;且前两种方法制备的氧载体的循环稳定性高;不同方法制备的氧载体在第1—4次还原过程中,CO2捕集率均在88%以上,CO2气产率伴随着C转化率的增大而增大,最后接近100%,燃烧效率均在90%以上,表明使用以上4种方法制备的氧载体对CO2捕集效果都较好,对可燃成分的利用程度也都较高。当褐煤作为燃料时,可优先采用由冷冻成粒法和喷雾干燥法批量制得的氧载体。
Freeze granulation, spray drying, impregnation and mechanical mixing methods were adopted to prepare Fe203/A1203 oxygen carriers. To identify the appropriate technologies for batch preparation of the oxygen carriers, the four preparation methods were compared in terms of yield rate, preparation period, physical and chemical characteristics and performance in chemical looping combustion (CLC) of lignite. The experimental results show that freeze granulation has the highest yield rate of carrier with the best mechanical strength. CLC tests of lignite demonstrate that the oxygen carriers prepared by freeze granulation and spray drying bring the highest carbon conversion rate, followed by impregnation and mechanical mixing; and the oxygen carriers prepared by the first two methods have higher chemical reactivity and more stable performance. In the four reduction processes with oxygen carriers prepared by all the four preparation methods, CO2 capture efficiencies exceed 88%; the yield rate of CO2 increases with the rate of carbon conversion, finally approaching 100%; and the combustion efficiencies are above 90%. These indicate that the oxygen carriers prepared by the four methods all have good performances for CO2 capture and high utilization degree of the combustible components. Freeze granulation and spray drying methods can be considered preferentially for batch preparation of oxygencarriers for the CLC of lignite.