添加煤灰及混合氧化物对石油焦CO2高温气化反应的影响

以化学组成相近的燃烧煤灰、气化煤灰和混合氧化物为添加剂，分别通过干混法和湿混法加入石油焦中，并借助热重分析仪在1200-1400 ℃下进行CO₂气化实验，研究高温下煤灰掺混方式、含量及物相组成对石油焦CO₂气化的影响，并使用混合氧化物替代实际煤灰研究其对石油焦的高温气化催化作用。结果表明，石油焦气化反应速率随煤灰添加量的增加而提升；气化温度为1200、1300 ℃时，使用干混法和气化煤灰对石油焦的气化促进作用较弱；但气化温度为1400 ℃时，改变煤灰和石油焦的掺混方式及其中活性金属存在方式，对石油焦气化反应几乎没有影响。这是高温下煤灰熔融，导致液态熔体与石油焦表面接触良好、活性金属自由度高以及传质阻力增加共同作用的结果。此时混合氧化物的催化指数与混合物中铁钙含量具有线性关系，即添加高铁钙含量的煤灰可以促进石油焦CO₂气化反应。

Effect of adding coal ashes and oxide mixtures on CO2 gasification reactivity of petcoke at high temperature

Three additives (combustion coal ash, coal gasification ash and oxide mixture) with similar chemical composition were added into petcoke by dry mixing and wet mixing. Their gasification reactivities under CO₂ atmosphere were investigated by a Thermo gravimetric Analyzer (TGA) at 1200–1400°C. The influence of mixing method, coal ash content and phase components on petcoke catalytic gasification was studied. The oxide mixture was used to simulate the catalytic effect of actual coal ash at high temperature. The results indicate that gasification reaction rate of petroleum coke is accelerated with increasing amount of coal ash. Dry mixing and coal gasification ash has less obvious effects on catalytic activity at 1200 and 1300°C. But the mixing method and mode of active metal has little influence on gasification reaction of petcoke at 1400°C. It is because the molten ash keeps good contact with petcoke, which makes reactive metals more freely and enhances mass transfer resistance. The catalytic index of the oxide mixtures has linear relationship with content of Fe₂O₃ and CaO during petcoke gasification at high temperature. This means coal ashes with high content of Fe and Ca could accelerate CO₂ gasification reactivity of petcoke.