煤热解半焦结构及其对制备型煤成型特性的影响

以不同热解条件下制取的陕西烟煤(YL)半焦为原料,使用预糊化淀粉为黏结剂冷压成型制取成型燃料,分析不同热解条件下获得的煤焦成型后的物理特性,研究热解条件对半焦挥发分和表面含氧官能团的影响规律,揭示热解半焦特性对其成型的影响机理。结果表明:热解停留时间和热解终温对半焦成型特性具有显著影响。热解停留时间增加和热解终温升高会降低半焦挥发分含量和表面含氧官能团,影响黏结剂颗粒和半焦颗粒之间的黏结作用,从而会降低半焦成型后的冷压强度和跌落强度。结果表明:挥发分质量分数在16%以上的半焦成型后冷压强度大于450 N,适宜成型;热解终温小于600℃且热解停留时间小于5 min的半焦表面含氧官能团含量较高,成型后冷压强度大于450 N,可用于成型。半焦的成型特性受其挥发分含量和表面含氧官能团的综合影响。

Structure of Semi-coke Obtained from Coal Pyrolysis and Its Influence on Properties of Briquette

In order to study the effects of pyrolysis conditions on semi-coke structure properties and physical properties of semi-coke briquette,semi-coke prepared from typical coal in different pyrolysis conditions was used to produce briquettes in cold pressing method.The physical properties of semi-coke obtained in different pyrolysis conditions after forming were anaylyzed.The effect of pyrolysis conditions on the volatile matter and surface oxygen-containing functional groups of semi-coke was studied.The influence mechanism of the properties of pyrolysis semi-coke on its forming was revealed.The results show that the pyrolysis residence time and pyrolysis final temperature have a significant influence on the forming characteristics of the semi-coke.Increased pyrolysis residence time and pyrolysis final temperature will reduce the mass fraction of volatile of the semi-coke and the oxygen-containing functional groups on the surface,which will affect the bonding between the binder particles and the semi-coke particles,thereby reducing the compressive strength and drop strength of the semi-coke after forming.The experimental results show that semi-coke with mass fraction of volatile above 16%has a compressive strength greater than 450 N after forming,which is suitable for forming;the semi-coke which pyrolysis final temperature is less than 600℃and pyrolysis residence time is less than 5 min has a high content of oxygen-containing functional groups on the surface,and the compressive strength after molding is greater than 450 N,which indicates that the semi-coke can be used for molding.The mass fraction of volatile of the semi-coke and the surface oxygen-containing functional groups comprehensively affect its molding characteristics.