反应气氛对褐煤气化反应性及半焦结构的影响

利用气流床反应器,在800~900℃条件下进行胜利褐煤的气化实验,考察水蒸气、O2及其混合气氛对褐煤气化特性和气体组成分布的影响,结合红外光谱分析和热重分析,解析反应气氛对半焦结构和半焦反应性的影响。结果表明,O2的加入优化了褐煤的水蒸气气化反应,促进了气体组成中H2体积分数的增加,最大增幅达到13%。气化后所得半焦的—OH,—CH3,—CH2—基团大幅减少,半焦的结构更加有序,芳香程度增加。采用热重分析对不同气氛下所得半焦的反应活性评价表明,随水蒸气体积分数的增加,制得半焦的气化反应活性降低;O2的加入进一步降低了反应活性指数,最低达到0.005min-1。O2环境下,低体积分数氧对制备的半焦反应活性影响较小。

Impacts of the gas atmosphere on the gasification reactivity and char structure of the brown coal

Shengli brown coal was gasified at 800-900 ℃ in a simulated entrained-flow reactor to investigate the effects of steam，oxygen and their mixture atmospheres on the gasification characteristics.The impact mechanism of gasifying agents on the char structures and reactivity were systematically clarified using Fourier Transform Infrared Spectroscopy(FTIR) and thermogravimetric analyzer(TGA).The results indicate that the addition of oxygen to the gasifying agent(i.e.steam) is considered to able to optimize the gasification reaction and increase the H2 yield，the largest increase valve of H2 being 13% in this study.The —OH，—CH3 and —CH2— functional groups drastically decrease during gasification.As a result，the regular structure of char and the aromatic degree increase.The reactivity of char from gasification in different atmospheres was evaluated by TGA，which shows the reactivity of char decrease with the increasing of the concentration of steam，and further addition of O2 restrain the reactivity index of char，whose minimum value obtained is 0.005 min-1.Under the oxygen atmosphere，the lower oxygen concentration demonstrates less influence on the reactivity of char.