月桂酸与硬脂酸粉尘爆炸过程热解动力学与火焰传播特性关系

综合应用同步热分析仪、改进的哈特曼爆炸测试装置及高速摄影系统，对月桂酸与硬脂酸粉尘的热解氧化特性及其在半封闭竖直管道内的火焰传播特性开展了实验研究，并分析讨论了月桂酸与硬脂酸粉尘爆炸燃烧过程中热解动力学与火焰传播特性的关系。结果表明，当粉尘云质量浓度为125 g/m3时，月桂酸粉尘云的火焰锋面结构比硬脂酸平滑，但硬脂酸粉尘的火焰传播速度明显大于月桂酸；随着质量浓度的增加，月桂酸和硬脂酸粉尘的火焰前锋逐渐变得离散，火焰传播速度逐渐增加，但速度差值逐渐减小；月桂酸粉尘的平均火焰传播速度在750 g/m3的粉尘云质量浓度下高于硬脂酸，火焰结构连续性显着降低。低质量浓度条件下月桂酸与硬脂酸粉尘云火焰传播特性差异主要由快速热解阶段的氧化放热特性决定，指前因子越大，参与热解和氧化反应的活性中心越多，氧化放热量越大，放热速率越快，火焰传播速度越快，火焰锋面结构由光滑连续向不规则离散的转变越快。随着粉尘云质量浓度的增加，火焰传播特性差异逐渐由活化能及火焰前锋预热区内氧气的质量输运过程控制，活化能越大，耗氧量越大，耗氧速率越快，越易导致火焰传播速度下降，火焰锋面趋于复杂，火焰结构连续性降低。

Relationship between pyrolysis kinetics and flame propagation characteristics of lauric acid and stearic acid dust explosion

The pyrolysis and oxidation characteristics and flame propagation characteristics in the semi-enclosed vertical pipe of lauric acid dust and stearic acid dust were studied by using the synchrotron thermal analyzer, improved Hartmann explosive test device and high-speed photography system, the pyrolysis kinetics was analyzed by Coats-Redfern method to obtain the kinetic parameters, and the influence of pyrolysis and oxidation characteristics on the law of flame propagation during the explosion and combustion of lauric acid and stearic acid dust was analyzed and discussed. The results show that, when the dust cloud concentration is 125 g/m3, the flame front structure of lauric acid dust cloud is smoother than stearic acid dust, but the flame propagation speed of stearic acid dust is significantly greater than that of lauric acid dust; with the increase of dust cloud concentration, the flame front structure of lauric acid dust and stearic acid dust gradually becomes discrete, and the flame propagation speed gradually increases, but the speed difference gradually decreases. The average flame propagation speed of lauric acid dust is higher than that of stearic acid dust at a dust cloud concentration of 750 g/m3, and the flame structure continuity is significantly reduced. The difference in flame propagation between lauric acid dust and stearic acid dust at low concentrations is mainly determined by the oxidation exothermic characteristics of the fast pyrolysis stage. The larger the pre-exponential factor, the more active sites involved in the pyrolysis and oxidation reactions, the larger the oxidation exothermic heat, the faster the exothermic rate, the faster the flame propagation speed, and the faster the flame frontal structure transition from smooth continuous to discrete complex. And with the increase of dust cloud concentration, the flame propagation difference is gradually controlled by the activation energy and the mass transport process of oxygen in the preheating zone of the flame front. The greater the activation energy, the greater the oxygen consumption, the faster the oxygen consumption rate, the easier it will lead to the decrease of flame propagation speed, the more complex the flame front, and the decrease of flame structure continuity.