片状煤焦颗粒CO2气化过程中形态及结构演变特性研究

采用高温热台显微镜观测了片状煤焦颗粒CO₂气化过程中的形态演变，并通过拉曼光谱分析了气化半焦的碳微晶结构，同时研究了气化温度（1000-1200℃）和煤焦初始当量直径（1.00-1.60 mm）对其CO₂气化过程中的形态及结构演变的影响规律。结果表明，与反应前期相比，反应后期的颗粒收缩（面积、体积、当量直径）更加剧烈。在所研究的气化温度范围内，随着气化温度的升高，煤焦颗粒的面积收缩率和体积收缩率逐渐减小。煤焦初始粒径显著影响颗粒收缩，1100℃气化温度下，颗粒的收缩趋势在初始粒径1.30 mm处出现转折。煤焦气化过程中碳消耗主导着表观密度的变化，在所研究的温度和粒径范围内，当碳转化率达到80%时，表观密度比线性减小到0.4以下。在相同气化温度下，随着碳转化率的增加，煤焦的石墨化程度先减小后增加，无定形碳含量先增加再减小。

Morphology and structure evolution of flaky char particles during CO2 gasification

High temperature stage microscope was applied to observe morphology evolution of flaky char particles during gasification. Raman spectroscopy was used to analyze crystalline structures of gasification semicoke. Effect of gasification temperature (1000–1200°C) and initial equivalent diameter (1.00–1.60 mm) on morphology and structure evolution were examined. The results show that particle shrinkage in later stage of gasification is more intense than that in early stage. Within tested gasification temperature, the particle ASR (area shrinkage ratio) and VSR (volumetric shrinkage ratio) decrease with increasing temperature. The initial particle size of char has a significant effect on particle shrinkage. At 1100°C the shrinkage trend of particle marks a turning point at initial diameter of 1.30 mm. The variation of char apparent density is dominated by carbon consumption. When the carbon conversion reaches 80%, the apparent density ratio linearly decreases below 0.4. At the same gasification temperature, with increasing carbon conversion the graphitization of char reduces first and then increases, while the amorphous carbon is opposite.