微分差热法确定沉降炉试验中低挥发分混煤的着火点

Derivative differential thermal method for determining igniting point of low-volatile blending coals in subsiding furnace

为了克服尝试法的工作量大、着火状态难以判断的缺点,以及避免等温度法的燃料发热量被掩盖所导致的误差,提出了一种微分差热法来确定沉降炉试验中低挥发分混煤的着火点.通过测量给粉前后的气流温度,得到表征煤粉气流吸热放热过程的差热曲线;对此差热曲线进行微分,将着火过程分为缓慢氧化阶段、过渡阶段和高速燃烧阶段;根据瞬间着火的定义将过渡阶段的谷底定义为着火点.在由2种无烟煤和1种贫瘦煤组成的混煤的7种工况下进行沉降炉试验,分析了煤粉挥发分和细度对着火点的影响.结果表明,微分差热法可以很好地区分不同工况,其结果表现出较强的规律性,此方法可用于判断沉降炉试验中低挥发分煤的着火点.

In order to avoid the disadvantages of traditional trying method and iso-temperature method such as heavy load, ignition state judgment and heating effect concealment, a derivative differential thermal method was put forward to determine the igniting point of low-volatile blending coals in subsiding furnace. A differential thermal curve that described the heat absorption and production course was achieved by measuring the temperatures of net airflow and pulverized-coal airflow. Then the ignite course was distin- guished as slow oxidation phase, transition phase and fast burning phase by the derivative of the differential thermal curve. Finally the igniting point was defined as the bottom of the transition phase. Seven operating conditions of blending coals composed of two species of anthracite and one species of meager lean coal were investigated in the subsiding furnace, and the effects of coal volatile and particle size were studied. The results indicate that the method can distinguish different operating conditions and the experimental da- ta have favorable law, which shows the feasibility of the derivative differential thermal method.