低品质煤提质后快速热解大分子挥发分产物的析出特性

Release characteristics of macromolecular volatile products during rapid pyrolysis of upgraded low-rank coals

对3种低品质煤进行200、250和300℃下的水热提质实验。将水热提质前后的煤样进行氮吸附测试和红外光谱测定,获得其孔隙分布和含氧官能团的变化规律。结果表明,水热提质后,各煤种平均孔径、比孔容明显降低,煤中羟基、羧基减少,环化程度升高,单环芳烃结构向多环芳烃转化,煤中有机质逐渐成熟,煤阶升高。利用快速热解仪在升温速率5000℃/s、终温1000℃条件下进行实验,获得低品质煤热解大分子挥发分的析出规律。结果表明,随着反应终温的升高,各煤种热解产生的脂肪烃含量减小、芳香烃的含量升高、酸类和酚类减少、酯类变化规律不明显。

3 low rank coals were dewatered and upgraded by hydrothermal process at 200 , 250 and 300 ℃. Nitrogen adsorption measurements and FT-IR spectra of the parent and upgraded coals were performed to get the change of pore distribution and functional groups. After hydrothermal treatment, the average pore diameter and specific pore volume drop rapidly. The content of hydroxyl and carboxyl decreases and the cyclized degree increases. The monocyclic aromatics change into polycyclic aromatics and the organic matter in coal is gradually mature, which reflect the coal rank becomes higher. Then, rapid pyrolysis were carried out in a CDS5000 Pyroprobe accompanied by a GC/MS at 5 000 ℃/s, 1 000 ℃ to investigate the release characteristics of macromolecular volatile products of these coals. With the final reaction temperature increasing, the content of aliphatic hydrocarbon, acids and phenols decreases, that of aromatic hydrocarbon increases. The esters in coals have no obvious variation law.