不同热解压力对煤焦结构的影响

The Effect of Pyrolysis Pressure on Char Physico chemical Structure

通过加压热重分析仪研究了胜利褐煤和府谷烟煤在0.1～5 MPa的热解特性,并采用元素分析仪、扫描电镜、X射线衍射仪和比表面积测定仪等系统考察了两种煤热解所得煤焦的化学结构和宏观物理结构随热解压力的变化规律。研究表明:加压对挥发分的析出有抑制作用,主要体现在促使焦油发生二次反应而生成碳黑沉积在煤焦颗粒表面,导致C/H摩尔比变大;热解压力对煤焦碳微晶结构的影响并不显著;随着热解压力的增加,煤焦的孔隙率和溶胀性增大。

In this work, the Shengli lignite and Fugu bituminous coal were pressurized pyrolyzed under high temperature pressurized thermogravimetric analyzer （PTGA） at the pressure range from 0.1 MPa to 5 MPa. After that, the resultant chars were systematically analyzed with elemental analyzer, X-ray diffraction （XRD）, scanning electron microscope （SEM） and N2 adsorption isotherm. It was found that： for both coals pyrolyzed under different pressures, elevated pressure inhibited the release of volatiles. Due to intense secondary reactions happened at higher pressure pyrolysis process, the tar was repolymerised and cracked more significantly, resulting in the carbon deposition on the particle surface, consequently, a higher C/H mole ratio. However, it seemed that the crystal structure of resultant char was not significantly affected by pyrolysis pressure. What＇s more, the porosity and swelling ratio of resultant char increased with elevated pressure, though it was not obviously observed from the SEM analysis of Shengli lignite.