Abstract:

The coal gasification reactivity in the syngas (H₂O, CO₂, H₂ and CO) was carried out in a fixed-bed tube reactor at atmospheric pressure. The effect of reaction temperature, raw gas composition and coal amount on gaseous products composition and carbon conversion rate was studied. The experimental results indicated that the CO flow rate increased significantly, while H₂ flow rate increased a little under the experimental conditions. The reaction between CO₂ and coal char was inhibited significantly. The effective gas (CO+H₂) concentration of syngas was able to increase through the reaction and its largest increase was 3.3% in the experimental conditions. The inhibition effect of CO and H₂ and the competitive effect between H₂O and CO₂ were obvious. The maximum coal reaction rate in the mixture gas was only 49% and 69% of the maximum coal reaction rate in pure gasification agent (H₂O, CO₂) in 1100℃ and 1300℃, respectively. The effect of diffusion and adsorption in the pore on the gasification reaction was obvious in the syngas. The random pore model was suitable for the experimental conditions. However, the volumetric reaction model and core shrinking model were poor in fitting of data.

Key words: coal gasification, fixed-bed, carbon conversion, kinetics, syngas

摘要：

在固定床管式炉反应器中进行了煤焦在H₂O、CO₂、H₂和CO混合气氛中气化特性的实验研究，考察了反应温度、原料气组成和加煤量对产物气组成以及碳转化率的影响。实验结果表明，在各实验条件下，合成气与煤焦反应后CO流量均增加最多，H₂少量增加。煤焦与CO₂的反应受到明显抑制。混合气体通过与煤焦反应可以提高有效气（CO+H₂）的含量，实验条件下反应出口气体中有效气浓度比反应结束时最多提高3.3个百分点。反应速率受气化剂之间的竞争和气化产物的抑制作用较为明显，在1100℃和1300℃时，煤焦在相同气化剂流量的合成气中的最高反应速率分别只有在纯气化剂（水蒸气或CO₂）中最高反应速率的49%和69%。受到多种气体组分之间的相互影响，气体在孔道里的扩散和吸附对反应影响更加显著，随机孔模型可以较好地拟合此类反应，而不考虑孔结构的均相模型和缩芯模型拟合度较差。

关键词: 煤气化, 固定床, 碳转化率, 动力学, 合成气