O_2/CO_2燃烧方式下Na元素对煤焦物化结构的影响

Effect of Sodium on Char Structure and Reactivity During Oxy-Fuel Combustion

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.