Abstract:

In order to reduce the harm caused by polyethylene (PE) dust explosion accidents, a 20-L explosion ball and a self-built dust deflagration flame propagation test system were used to conduct explosion suppression experiments. The suppressive effects of ammonium polyphosphate (APP) are examined by evaluating pressure and flame propagation behavior. A synchronous thermal analyzer assesses APP’s impact on the thermal decomposition of PE dust. The reaction kinetics of PE and a mixture of APP and PE (I=1.0) during the rapid pyrolysis phase were derived employing the Coats-Redfern method. Through an in-depth analysis of explosion overpressure, flame propagation, thermal decomposition, and explosion by-products, it becomes evident that APP confers a synergistic explosion suppression effect on PE dust’s gas and condensed phases. The findings illustrate that APP markedly diminishes PE dust’s maximum explosion pressure P_max, maximum explosion pressure rate of rise (dP/dt)_max, and flame propagation speed. When the inhibition ratio was 1.0, the pressure peak vanished, indicating complete suppression of PE dust. Additionally, pyrolysis characteristics indicated that APP introduction attenuates PE dust’s pyrolysis rate and postpones pyrolysis and oxidation events. Pyrolysis kinetics model analysis showed that PE dust adheres to the A3 model during rapid pyrolysis, while it transitions to the R2 model with APP addition, with corresponding average activation energies of 137.34 kJ/mol and 228.52 kJ/mol. Significantly, APP integration results in a pronounced rise in PE’s apparent activation energy, highlighting the deceleration of PE particles’ oxidative pyrolysis. Employing FTIR analyses, a pronounced reduction in the characteristic —CH₂ and —OH peaks with APP was discerned. It’s elucidated that APP provides synergistic explosion inhibition effects in both the gas and condensed phases, primarily by curtailing free radicals via phosphorus-volatile release during pyrolysis and fostering a porous, dense surface carbon layer to inhibit deflagration. These insights lay the groundwork for the development of superior powder explosion suppressants specific to PE dust.

Key words: dust, explosion, flame propagation, polyethylene, ammonium polyphosphate, pyrolysis characteristics, kinetic

摘要：

为了减小聚乙烯（PE）粉尘爆炸事故所带来的危害，使用20-L爆炸球以及自主搭建的粉尘爆燃火焰传播测试系统进行爆炸抑制实验，从爆炸压力行为和火焰传播行为探究了聚磷酸铵（APP）对PE粉尘的抑制特性。通过同步热分析仪分析了APP对PE粉尘热解特性的影响，采用Coats-Redfern方法计算了PE和APP-PE混合粉尘（I=1.0）在快速热解阶段的反应动力学参数，并结合爆炸产物探究了其抑制机理。结果表明：APP可有效降低PE粉尘的最大爆炸压力、最大爆炸压力上升速率以及火焰传播速度，当抑制比为1.0时，PE粉尘爆炸压力峰消失，标志着在该抑制比下被完全抑制。此外，通过分析热解动力学模型发现PE粉尘在快速热解阶段遵循A3模型，添加APP后遵循R2模型，其平均活化能分别为137.34 kJ/mol和228.52 kJ/mol，活化能的增加，说明APP的加入减缓了PE粉尘的氧化和热分解，表现出显著的抑制效果。研究结果可为防治PE粉尘爆炸提供理论依据和技术支撑。

关键词: 粉体, 爆炸, 火焰传播, 聚乙烯, 聚磷酸铵, 热解特性, 动力学