神华煤流化床气化带出细粉的粒径分离及分离后细粉的CO_2气化特性研究

Particle size classification and CO_2 gasification of the char fines from fluidized bed gasification of Shenhua coal

按粒径将神华煤流化床气化带出细粉(简称细粉)依次筛分为七个组分。采用工业分析仪、元素分析仪、热重分析仪、X射线粉末衍射仪、物理吸附仪等对各组分细粉的基本物化特性、CO2恒温和程序升温气化行为进行了考察。在此基础上,对气化活性差异及其原因进行初步探索。结果表明,细粉经历部分气化后,由于挥发分的析出,细粉的固定碳含量较原煤高,但较相应半焦低。细粉的粒径分布范围较宽,呈近似"M"形分布。随细粉粒径减小,灰分含量增大,而含碳量减少。CO2恒温气化与程序升温气化获得的气化反应活性顺序一致:均随细粉粒径的减小先逐渐降低而后又逐渐升高。不同细粉气化反应活性的差异与其自身的石墨化程度及灰分含量有关,而在研究实验条件下与孔径结构关系不大。

The char fines from fluidized bed gasification（ fines for short） are classified into 7 components based on particle size. The basic physicochemical properties,the constant and programmed increasing temperature CO_2 gasification behaviors were investigated by coal quality analyzer, elemental analyzer, X-ray powder diffractometer,gas sorption analyzer and thermogravimetric analyzer. The difference of gasification reactivity and its reasons were discussed. The results showthat after partial gasification,fixed carbon of the fines is higher than that of its parent coal but lower than the corresponding coal char because of the escape of volatiles. The particle size distribution of fines is very wide and multimodal distribution with the shape of ＂M＂. In addition,the ash content of fines approximately increases with decreasing particle size. However,the carbon content decreases with decreasing particle size. Both the constant and programmed increasing temperature CO_2 gasification showthe same result. The gasification reactivity firstly decreases and then gradually increases with decreasing particle size. Furthermore,the carbon crystalline structure and ash content are contributed to the difference in gasification reactivity of fines,and the different reactivity is not related to the pore structure in this experimental condition.