恒温热重法单颗粒煤焦燃烧动力学  

Single coal particle combustion characteristics and kinetics study using thermogravimetric method under constant temperature

作　　者：旷戈[1,2] 张济宇[3] 

机构地区：[1]中国科学院山西煤炭化学研究所 [2]福州大学化学工程技术研究所,福建福州350002 [3]福州大学化学工程技术研究所

出　　处：《化工学报》2006年第1期140-145,共6页CIESC Journal

基　　金：国家自然科学基金项目(20376014);福建省科技厅重点项目资金(HG9901).~~

摘　　要：A thermogravimetric method under constant temperature replacing the beginning inert gas with burning air was established in this study for determining the combustion kinetics of single char particle. The combustion process of three types of coals, Fujian Longyan coal, Fujian Yong’an coal and Shandong coal, with diameter of 3.0—4.5 mm, in thermobalance under 900℃ was discussed using the familiar shrinking-core model.While the combustion of single char approached the end, the outside and the ash layer diffusion resistances tend to be zero as the reaction resistance dominated in the total resistance of combustion.Therefore, at this stage the inherent oxidation reaction constant (k_R) of the above char samples were estimated by analyzing the total resistance of combustion.The good agreement of combustion reaction rate between data determined in this study and calculated values obtained from reference in the drop tube furnace system, implied that the inherent oxidation reaction constant (k_R) determined by the thermogravimetric method under constant temperature was satisfactory and valuable. The gas diffusion through the ash layer of char particle during combustion process was discussed also. At the ash layer thickness half the char radius, the ash layer resistance in the combustion process reached a maximum value, at which the total resistance of combustion,1/K,was less than 25 s·m -1 and would be close to the reaction resistance,1/k_C,approaching the end of combustion. So the effects of gas diffusion resistance through ash layer on char combustion process could be ignored during the whole combustion process.A thermogravimetric method under constant temperature replacing the beginning inert gas with burning air was established in this study for determining the combustion kinetics of single char particle. The combustion process of three types of coals, Fujian Longyan coal, Fujian Yong＇an coal and Shandong coal, with diameter of 3.0-4.5 mm, in thermobalance under 900℃ was discussed using the familiar shrinking-core model. While the combustion of single char approached the end, the outside and the ash layer diffusion resistances tend to be zero as the reaction resistance dominated in the total resistance of combustion. Therefore, at this stage the inherent oxidation reaction constant （kR） of the above char samples were estimated by analyzing the total resistance of combustion. The good agreement of combustion reaction rate between data determined in this study and calculated values obtained from reference in the drop tube furnace system, implied that the inherent oxidation reaction constant （kR） determined by the thermogravimetric method under constant temperature was satisfactory and valuable. The gas diffusion through the ash layer of char particle during combustion process was discussed also. At the ash layer thickness half the char radius, the ash layer resistance in the combustion process reached a maximum value, at which the total resistance of combustion, 1/K, was less than 25 s ·m^-1 and would be close to the reaction resistance, 1/kc, approaching the end of combustion. So the effects of gas diffusion resistance through ash layer on char combustion process could be ignored during the whole combustion process.

关 键 词：热重分析 动力学 灰层 煤焦 颗粒 

分 类 号：TK224.1[动力工程及工程热物理—动力机械及工程]