将低钠煤(H-煤)和高钠煤(Na-煤)分别在沉降炉中进行制焦实验,研究了钠对焦样的孔隙结构、碳微晶结构以及反应性的影响。研究表明,煤中钠含量增加后,在N2气氛下,非灰基质失重率V*会下降;而在CO2气氛下,V*却会升高。煤焦的碳化学有序度IG/IAll与V*具有关联性,在有Na的催化时,其与反应性的关联性被破坏。焦的反应性主要由焦的孔隙结构和焦中Na的含量来确定,在动力控制区,Na的催化作用是引起焦反应性发生改变的主要因素。
Pyrolysis/gasification experiments of H- and Na-form coal samples were conducted separately in a lab-scale drop tube furnace (DTF) under N2 and CO2 atmospheres. The effect of sodium on the char porous & crystalline structure and combustion reactivity in the presence of a high concentration of CO2 was investigated. The results showed that, compared with char from H-form coal, the volatile yield of char from Na-form coal was higher under CO2 atmosphere, while lower under N2 atmosphere. Relation was found between the volatile yields and Raman area ratios Ia/IAn for chars from different coals. The presence of sodium in the chars had an impact on the evolution of the char crystalline structure, and destroyed correlations between IG/IAn ratio and reactivity of chars. Chars reactivity was affected by porous structure coupled with catalysis of sodium, and under a reaction-controlled regime during thermogravimetric analysis, catalysis of sodium played a dominant role in reactivity alteration.
参考文献
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