煤焦破碎及颗粒物形成的逾渗模拟  

Percolation Modeling of Char Fragmentation and Particulate Matter Formation

作　　者：温昶[1] 徐明厚[1] 于敦喜[1] 岳良[1] 周科[1] 占中华[1] 姚洪[1] 

机构地区：[1]煤燃烧国家重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《中国电机工程学报》2011年第11期45-50,共6页Proceedings of the CSEE

基　　金：国家自然科学基金项目(50720145604;50721005);中央高校基本科研业务费资助(HF07162010121)~~

摘　　要：采用座逾渗模型,引入计算机控制扫描电镜(computer-controlled scanning electron microscope,CCSEM)矿物原粒径数据作模型初始矿物数据,考察了不同孔隙分布对煤焦转化与破碎的影响,煤焦转化过程对破碎程度的影响,以及煤焦破碎和内在矿聚合对飞灰颗粒物尤其是1～10μm颗粒物最终分布的影响。模拟结果表明:煤焦初始孔隙率越大,表面反应面积和破碎次数均越大。当φ≥0.4时,煤焦破碎明显集中于转化率为0.4～0.7的阶段,且峰值有一定的向转化前期移动的趋势。初始孔隙率φ越大,颗粒破碎就越剧烈,内在矿聚合概率小,10μm以内颗粒物的数目明显增大。随着φ值的增大,生成颗粒物的浓度尤其是1～10μm颗粒物的浓度逐渐升高,最终颗粒物浓度分布到在3～5μm和6～8μm存在2个峰值,这与实际燃烧生成的中间模态和粗模态颗粒物的峰值基本吻合。A site percolation model of char fragmentation and particulate matte （PM） formation during dense and porous char combustion was reported in this paper. The sizes of included minerals in pulverized coal were determined on the computer-controlled scanning electron microscope （CCSEM）. The model presents the influence of initial pore distribution during char oxidation and fragmentation, the impact of char conversion process on the extent of fragmentation, and the particulate matters （PM） sizes distribution, especially 1-10pro particles. The results show that with increasing initial char porosity （Ф）, the surface reaction area increases. As Ф is equal or greater than 0.4, char fragmentation concentrates on the stage which the rates of char conversion are 0.4-0.7, and it looks like that the maximum value of fragmentation will transfer to priorstage if having larger porosity. The enhanced Ф shows a positive effect on the increase of the number and concentration of PM less than 10 μm. This may be attributed to char fragment more drastic and the probability of mineral coalescence reduces. Finally two peak values are observed in the particle size and concentration distribution, 3-5 μm and 6- 8 μm respectively. It is similar to the peak value of the central mode and super-micron mode of PMl0 observed experimentally during pulverized coal combustion.

关 键 词：座逾渗模型 计算机控制扫描电镜 颗粒物 煤焦 破碎 矿物聚合 

分 类 号：TK222[动力工程及工程热物理—动力机械及工程]