基于CaSO4载氧体的煤化学链燃烧还原反应实验研究

基于CaSO4载氧体的煤化学链燃烧技术，采用小型流化床模拟燃料反应器，对煤气化–CaSO4还原反应展开实验研究。水蒸气作为气化及流化介质，煤气化气体产物(CO、CH4、H2)与CaSO4发生还原反应。结果表明，煤气化是煤气化–CaSO4还原反应过程的控制步骤；CH4、H2累积量随温度升高呈减少趋势，高于950 ℃时反应产物中无CH4、H2，温度低于950 ℃时CO累积量随温度增高亦呈减少趋势， 但高于950 ℃时CO累积量随温度升高反而略有增加；煤气化反应的碳气化效率以及煤气化–CaSO4还原反应的C–CO2转化率均随温度而增大，最大值分别达95.9%、91.5%。CaSO4在CH4、H2气氛的反应活性随温度升高而显著提高，而在CO气氛下其反应活性较弱；煤气化–CaSO4还原反应后的载氧体颗粒出现轻微磨损，扫描电镜分析表明反应后载氧体颗粒的比表面积增大，950 ℃时存在轻微烧结现象，但对载氧体反应活性影响不大。

Experiments on Reducing Reaction for Chemical Looping Combustion of Coal With CaSO4 Oxygen Carrier

Chemical looping combustion (CLC) of coal with CaSO4 as an oxygen carrier was experimental investigated in a fluidized bed as a fuel reactor. Coal and steam were introduced to the fuel reactor that contained CaSO4 particles. The processes of both coal gasification and the reduction of CaSO4 with the gasification syngas were carried out. The experimental results showed that coal gasification is the control step of chemical looping combustion process of coal. The content of unreacted CH4, H2 had a trend of decreasing with the increasing of temperature. When the temperature was higher than 950 ℃ there were no CH4, H2 existed. At the temperature of 950 ℃ the gas production of CO got a minimum, but with a further increase of temperature the accumulation of CO increased slightly. Carbon conversion and conversion of C-CO2 increased with the temperature. The maximum of carbon conversion got 95.9%, and conversion of C-CO2 91.5%. The reactivity of reduction of CaSO4 particles with CH4 and H2 increased with the temperature. However, due to sintering on the oxygen carrier particles when the temperature exceeded 950 ℃, its reduction reactivity decreased somewhat. There existed a low attrition in calcium-based oxygen carrier particles.