低氧气氛下煤粉燃烧特性及动力学

采用热重分析仪研究了不同煤粉在烟气气氛下的燃烧特性,考虑了升温速率和氧气浓度对燃烧特性的影响。研究结果表明:低氧条件、高升温速率下,煤粉的TG、DTG曲线均向高温区靠近,燃烧速率变慢,燃尽时间增长;改变氧气浓度和升温速率对煤的着火温度影响不大,在一定氧浓度(5%~15%)范围内,高水分低阶煤采用烟气干燥输送的制粉系统,能满足其安全性要求;氧气浓度和升温速率主要对煤的燃烧阶段产生影响,随着升温速率的升高和氧浓度的降低,燃尽温度明显升高,且氧浓度对燃烧特征参数的影响大于升温速率的影响。此外,采用Coats-Redfern积分法对煤粉在程序升温过程中的燃烧反应做了相应的动力学分析。结果表明:氧气浓度和升温速率的变化均对活化能产生影响,且随着氧气浓度的降低,煤阶对活化能的影响逐渐减弱。

Coal Combustion Characteristics and Kinetics Analysis in Hypoxic Atmosphere

A series of pulverized coal combustion experiments in flue gas were performed in a thermogravimetric analyzer(TGA)to study the effects of oxygen concentration and heating rate on combustion characteristic.Experimental results indicate that TG and DTG curves tend towards higher temperature zone while burning rate decreased with lower oxygen concentration and higher heating rate.The change of oxygen concentration and heating rate has little effect on the ignition of coal,and it is relatively safe for drying and conveying low rank coal with flue gas while the oxygen concentration is between 5%and 15%.In the process of coal oxidation,the changes of oxygen concentration and heating rate can affect the characteristic temperature and combustible parameter of coal.The burn-out temperature increases obviously while the oxygen concentration decreased and the heating rate increased,but the effect of oxygen concentration on them is greater than the effect of heating rate.In addition,the kinetics analysis of coal combustion in the heating process was carried out by Coats-Redfern method.The results show that the experimental condition has some effect on the activation energe.The effect of the coal categories on activation energy decreases with decreased oxygen concentration.