粉煤颗粒粒度对燃烧特性影响热分析

ANALYSIS OF THE EFFECT OF COAL POWDER GRANULARITY ON COMBUSTION CHARACTERISTICS BY THERMOGRAVIMETRY

采用德国Netzsch公司生产的STA 409C型热天平研究了合山与晋城2个煤种各4个不同粒度的煤样的燃烧行为,其升温速率均为20℃/min、所用气体为O2、气体流量均为70ml/min。煤样的颗粒粒度由英国Malvern公司的 MAM5004型激光粒度分析仪测定。煤样的比表面积由美国Micromeritics公司的ASPA2000型比表面积及孔径分布分析仪测定。根据实验数据计算了各试验煤样在高、低温度段的燃烧动力学参数:表观活化能与频率因子,用重量加权平均法计算了各煤样的平均表观活化能,并研究了煤样的比表面积与平均表观活化能的关系。结果表明:随着粒径的减小,BET比表面积越大,煤粉燃烧热重曲线的分界更明显,最大燃烧速率出现得越早;活化能越小,着火温度降低,着火提前。煤粉的燃烧特性随粒径减小而得到改善。

The pulverized coals of four different particle sizes, which are taken from Heshan and Jincheng respectively under investigation. Particle sizes of pulverized coals are analyzed by Malvern MAM5004 Laser Mastersizer made in United Kingdom and special surface area BET are analyzed by Micromeritics ASPA2000 specific surface area and porediameter analysis apparatus made in United States. The effect of coal powder granularity on combustion characteristics are invested by STA 409C thermobalance made in Germany,the heating rate is 20℃/min, O2 flow rate is 70ml/min. Quantitative analysis the combustion process by divided it into two regions as the low temperature region and high temperature region,make out the chemical kinetics parameters of each region,in terms of the apparent activation energy E and thepre-exponential factor A, and mean apparent activation energy. The relations of BET with mean apparent activation energy also been discussed in this paper. Experimental investigation has proved that the specific surface area is greatly increased.Maximum combustion rate occur early, apparent activationenergy are decreased while the coal particle size decreased,reduced ignition temperature and ignition early. Coalcombus-tion process can be perfected, while the coal particle size decreased.