煤矸石绝热氧化的失重阶段及特征温度点分析

Analysis on the zero-g period and characteristic temperature of coal gangue during adiabatic oxidation process

为研究煤矸石绝热氧化过程的具体失重阶段和失重特征温度点,采用综合热分析仪研究了不同工况下氧气浓度和升温速率对煤矸石绝热氧化进程的影响。实验结果表明:煤矸石在不同工况下的绝热氧化失重过程可划分为4个阶段,即外在水分失水失重阶段、内在水分失水失重阶段、挥发分燃烧失重阶段和固定碳燃烧失重阶段。在同一氧气浓度(20%)下,随着升温速率的提高,煤矸石绝热氧化的TG曲线向高温区偏移,4个阶段的特征温度点(起点、中点、拐点和终点)随升温速率的增大而线性增大,挥发分和固定碳燃烧失重阶段的最大燃烧速率呈增大趋势,但各个阶段的质量变化基本相同。在同一升温速率(10.0℃/min)情况下,随着氧气浓度的提高,煤矸石绝热氧化的TG曲线向低温区偏移,外在水分和内在水分失水失重阶段的特征温度点(起点、中点、拐点和终点)和失重质量基本不受氧气浓度增大的影响,挥发分和固定碳燃烧失重阶段的特征温度点(起点、中点、拐点和终点)随氧气浓度的增大而降低。

Adiabatic oxidation processes of coal gangue under the different conditions of oxygen concentration and heating rate were analyzed by STA technology to investigate its specific zero-g period and characteristic temperature of every zero-g period.Based on the thermal analysis experimental results,the zero-g periods of coal gangue during adiabatic oxidation process under the different conditions is separated into four stages which are respectively the zero-g period of surface moisture,inherent moisture,volatile combustion and fixed carbon combustion.In the case of the same oxygen concentration which is 20%,the TG curves of adiabatic oxidation of coal gangue move to the high temperature zones along with the increasing of the heating rate,and the characteristic temperatures of every stage which are respectively the starting point,midpoint,inflection point and terminal point increases linearly when the heating rate increases,and the maximum burning rates of the zero-g periods of volatile combustion and fixed carbon combustion also increases when the heating rate increases,but the weight changes of every stage are basically the same.In the case of the same heating rate which is 10.0 ℃/min,the TG curves of adiabatic oxidation of coal gangue move to the low temperature zones along with the increasing of the oxygen concentration,and the characteristic temperatures which are respectively the starting point,midpoint,inflection point and terminal point and the weight changes of the zero-g periods of surface moisture and inherent moisture are basically the same along with the increasing of the oxygen concentration,but the characteristic temperatures which are respectively the starting point,midpoint,inflection point and terminal point of the zero-g periods of volatile combustion and fixed carbon combustion decreases linearly along with the increasing of oxygen concentration.