水分促使抛光铝粉热自燃临界温度和诱导时间

Critical Temperature and Induction Time of Spontaneous Combustion of Polished Al Powder Induced by Water

采用等温与非等温C80微量热试验及Semenov和Frank-Kamenetskii热自燃理论对水分促使抛光铝粉热自燃的临界温度和各阶段诱导时间进行了研究.结果表明,Al_(2)O_(3)-H_(2)O与Al-H_(2)O反应均遵循Arrhenius动力学机制,反应活化能分别为61.7和138.6 kJ·mol^(-1);堆积铝粉热自燃诱导时间由两阶段组成,第一阶段为氧化铝薄膜水解时间,第二阶段为铝-水反应放热系统由环境温度达到不返还温度T_(NR)的时间,该时间取决于铝粉堆积状态和堆积质量.当环境温度为25℃时,第一阶段诱导时间为155.6 h;当25 kg铝粉以圆柱形集尘桶状态堆积时,相同环境温度下第二阶段诱导时间为0.7 h,铝粉自燃临界温度为24.9℃,铝粉具有热自燃危险性,且诱导时间随堆积质量增加而延长.

Isothermal and non-isothermal C80 micro-calorimetry experiments and Semenov and Frank-Kamenetskii spontaneous combustion theory have been applied to study the critical temperature for spontaneous combustion of the polished aluminum powder induced by water and the induction time of each reaction stage.The results show that both Al_(2)O_(3)-H_(2)O and Al-H_(2)O reactions follow the Arrhenius kinetic mechanism,with the activation energy being equal to 61.7 and 138.6 kJ·mol^(-1),respectively.The induction time of aluminum powder consists of two stages.The first stage is the time for alumina film hydrolysis,and the second stage is the time for the aluminum-water exothermic reaction system to reach the non-return temperature T_(NR) from the ambient temperature,depending on the accumulation state and the deposit mass of the aluminum powder.When the ambient temperature is 25℃,the induction time of the first stage is 155.6 h.When aluminum powder of 25 kg is deposited in a cylindrical dust collecting drum,the induction time of the second stage is 0.7 h with the same ambient temperature,and the critical temperature for spontaneous combustion is 24.9℃.The aluminum powder has the risk of spontaneous combustion,and the induction time increases as the deposit mass increases.