煤粉颗粒热解时的膨胀与其物理化学性质的关系

Relationship Between Swelling Behavior and Physical/Chemical Properties of Coal Particles During Pyrolysis

通过建立数学模型来研究煤粉颗粒热解时的膨胀规律,用分形孔隙模型生成煤粉的孔隙结构,描述热解过程发生的化学反应、气体在孔隙中的扩散和煤粉颗粒的膨胀与收缩.对模型计算结果进行拟合,得到描述煤粉颗粒膨胀的微分方程,通过与其他研究者模型计算结果的对比验证该微分方程,分析了煤种的官能团含量、煤粉颗粒的孔隙率和比表面积对其膨胀的影响,并定义了一个综合了煤的物理化学性质的参数X.结果表明:官能团含量上升,煤粉颗粒的最大膨胀率和煤焦的膨胀率增大;孔隙率或比表面积增大,煤粉颗粒的最大膨胀率和煤焦的膨胀率减小;参数X越大,煤粉颗粒在热解过程中会发生更大的膨胀.

To investigate the coal particle swelling behavior during pyrolysis, a numerical model was developed by using the fractal pore model to generate the coal particle pore structure, and then to describe the chemical reactions, gas diffusion and the swelling and contraction behavior of coal particles during pyrolysis. Based on fitted curves with model results, a differential equation was obtained to describe the coal particle swelling, which was validated by comparing with predicted results of other researchers, and was then used to study the effects of following factors on the swelling, such as the functional group content, particle porosity and specific surface, etc. , and finally a comprehensive parameter X was defined to characterize the swelling ability of coal particles in consideration of above factors. Results show that both the maximum coal particle swelling ratio and the char swelling ratio increase with rising functional group content, and with reducing porosity and specific surface area. The larger the X is, the greater the swelling of coal particles will be during pyrolysis.