氧化钙对胜利褐煤焦水蒸气气化反应性能及微结构的影响

研究了CaO对胜利褐煤焦水蒸气气化反应性能及微结构的影响。脱除矿物质的胜利褐煤混合不同含量的CaO后在1 100 ℃下进行热解得到相应的煤焦,采用BET、XRD和Raman技术对其进行表征,同时在微型固定床反应器上对所制得煤焦进行水蒸气气化实验。比较添加CaO不同含量煤焦的反应性表明,添加2%(质量分数)的CaO对煤焦水蒸气气化的催化作用很小,而CaO添加量增大到5%时,煤焦的气化反应性能明显提高。煤焦比表面积随CaO添加量的提高而增大。XRD结果表明,在热解过程中,CaO能有效地抑制煤焦向石墨化方向发展趋势。煤焦002和100峰的峰强度随CaO添加量的增加而降低,且煤焦芳香度从66.8%降至39.9%。Raman光谱结果表明,随着CaO添加量的增加,I_D/I_G由1.363增加至1.541,I_G/I_all由0.423减少到0.394。意味着由于Ca的催化作用,煤中大芳香环结构的裂解速率明显增加,且随CaO添加量的增多,煤焦的无序化程度和晶格缺陷均增大。

Influence of calcium oxide on Shengli lignite char microstructure and steam gasification performance

The Influence of calcium oxide on Shengli lignite char microstructure and steam gasification performance was studied. Demineralized coal samples were loaded with different content of calcium oxide and then pyrolyzed at 1 100 ℃. The char is gasified with steam in a micro fixed-bed reactor. The X-ray diffraction apparatus and Raman spectra apparatus were used to characterize the structure of coal char. The results show that the char with 5% calcium exhibits the highest gasification reactivity, while the catalysis for the steam gasification of char with 2% calcium is almost negligible. The results of XRD suggest that calcium can effectively hinder the carbon graphitization in the process of pyrolysis. The intensity of (002) and (100) peaks of char decreases with the rise of calcium loading. With the increase of calcium loading, the aromaticity f_a is reduced from 66.8% to 39.9%. Raman spectra results show that I_D/I_G increases from 1.363 to 1.541 and I_G/I_all reduces from 0.423 to 0.394 with the increase of calcium loading, respectively. It means that the decomposition of large polyaromatic ring structure in coal is greatly enhanced by the catalytic action of calcium, and the disordering degree and the structural defects of char increase with the increase of calcium loading.