泥炭粒径对阴燃蔓延速率影响的实验研究

实验研究了自然对流下,不同颗粒粒径(1mm,1mm~2mm,2mm~3mm,3mm~4mm,4mm)的泥炭向下阴燃现象。通过测量泥炭阴燃内部温度,分析了泥炭颗粒粒径大小对泥炭阴燃峰值温度、峰值温度处阴燃蔓延速率、水分蒸发前锋(T=90℃)蔓延速率、泥炭热解前锋(T=312℃)蔓延速率和炭氧化前锋(T=421℃)蔓延速率的影响。实验结果表明:各颗粒粒径泥炭的阴燃峰值温度在510℃到710℃之间变化,平均峰值温度大小呈现随着粒径的增大而减小的趋势。除了粒径1mm的泥炭阴燃实验外,其他粒径的泥炭阴燃稳定蔓延阶段峰值处的蔓延速率随着粒径的增大而增大。实验发现粒径2mm泥炭阴燃蔓延速率随着粒径的增大而增大,而粒径3mm泥炭阴燃蔓延速率随着泥炭粒径的增大而减小,粒径2mm~3mm是一个界限值。

Influence of particle size on the spreading rate of peat smoldering: An experimental study

The natural downward smoldering of peat with different particle sizes （〈1 mm, 1--2 mm, 2--3 mm, 3--4 mm, 〉4 mm） was investigated experimentally. By measuring the internal temperature profiles of the smoldering peat, the influence of particle size on the peak temperature inside peat samples, the spreading rate of front where peak temperature reached, the spreading rate of moisture evaporation front at 90℃, the spreading rate of peat pyrolysis front at 312℃ and the spreading rate of char oxidation front at 421℃ was analyzed. The results showed that the peak temperature of smoldering for each particle size was between 510℃ and 710℃. The average peak temperature decreased with increasing particle size. The spreading rate of front where peak temperature reached during the stable propagation period of smoldering increased with increasing particle size, except for particle size 〈1 mm. The relationship between the smoldering spread rate and the particle size in stable propagation was also analyzed. It was found that for particle size （2 ram, the spreading rates increased with increasing particle size, while they decreased when the particle size is 〉3 ram, which indicated 2--3 mm was the critical value of particle size.