煤焦破碎成灰模型研究

A MODEL STUDY ON CHAR FRAGMENTATION AND ASH FORMATION

本文从颗粒破碎的角度,建立了燃烧过程中单颗煤焦的逾渗破碎及其成灰模型,并深入研究了初始大孔隙率对颗粒破碎程度以及残灰粒径分布的重要影响。模拟结果再现了无大孔存在(φ=0)情况下,单颗煤焦生成单颗残灰的实验事实;研究结果还表明,在所考察的取值范围内,初始大孔隙率φ越大,煤焦颗粒破碎越剧烈,燃烧前期的破碎程度也随之升高,同时,φ越大,燃烧过程中单颗煤焦生成残灰的数目越多,平均粒径越小,而且残灰主要集中在粒径较小的范围内。

A percolation model is developed to simulate the fragmentation of a single char particle during char combustion and the ash formation process from the point of view of particle fragmentation. Further efforts have been made to study the important influence of the macroporosity （φ） of coal chars on the extent of fragmentation and the residual ash particle size distribution. The results indicate the reality that a single char particle will evolve into a single residual ash when no maropores exist （φ=0）. But with the increase of the macroporosity （φ）, coal char particles fragment more intensively and the fragmentation number at the early stage of char combustion becomes higher. As a result, a single char particle produces more small residual ash particles resulting in a smaller mean particle size.