针对粉煤密相输运床气化技术,使用滴管炉对云南褐煤(YN)、山东次烟煤(SD)和内蒙烟煤(NM)进行快速升温热解实验,应用数字成像颗粒分析仪同时获得颗粒粒径和球形度,研究了不同煤阶、粒径、温度、预烘干除水对煤焦形貌参数的影响.结果表明:随着煤阶提高,热解膨胀度和球形度均提高,1 273 K热解后YN褐煤因收缩和破碎,膨胀度为0.66;SD煤和NM煤的膨胀度均大于1;焦的球形度因热解软化,较原煤均略有提高;NM烟煤随着热解温度的提高,膨胀度降低,球形度先增加后减小;小粒径NM煤颗粒的膨胀度和球形度均更高.干燥NM煤的膨胀度显著高于含水原煤,且随温度升高,膨胀度提高,变化规律与含水原煤相反;球形度随温度变化规律相似,但却低于原煤,预烘干除水对NM煤焦形貌的影响显著.
For the development of dense phase transport gasification technology,lignite (YN),sub-bituminous (SD) and bituminous (NM) coals were pyrolyzed in a drop-tube furnace.A digital image particle analyzer was used to obtain both swelling ratio and sphericity simultaneously.The effects of coal rank,particle size,temperature and drying pretreatment on char morphology were studied.With the increase of coal rank,the swelling ratio and sphericity were both increased.YN lignite underwent an obvious shrinkage with swelling ratio about 0.66 after the 1 273 K pyrolysis.SD sub-bituminous and NM bituminous were more than 1.The particle sphericity was increased after pyrolysis because of the softening.With the increase of pyrolysis temperature,the swelling ratio of NM coal decreased,and the sphericity increased first and decreased then.Finer NM coal particles resulted in higher swelling and roundness.The swelling ratio of dried NM coal chars were higher,and increased with a higher pyrolysis temperature,which is contrary to the raw coals with moisture.The variation of sphericity with temperature was similar to the raw coal but the sphericity of dried coal char was lower than the raw coal.Drying pretreatment before pyrolysis experiments could significantly influence the morphology of chars.