黑龙江大兴安岭地区兴安落叶松人工林阴燃过程中的温度变化及主要气体释放特征

唐抒圆; 高博; 于渤; 王晓迪; 尹赛男; 单延龙; 韩喜越; 曹丽丽

doi:10.12171/j.1000-1522.20210118

黑龙江大兴安岭地区兴安落叶松人工林阴燃过程中的温度变化及主要气体释放特征

Temperature changes and main gas release characteristics of Larix gmelinii plantations during smoldering in Daxing’anling Mountain region of Heilongjiang Province, northeastern China

摘要

摘要:
目的模拟阴燃过程，研究土壤表层温度变化规律和气体释放特征，为阴燃燃烧动力学、阴燃蔓延机制和阴燃火灾监测等研究提供理论支持。
方法以大兴安岭地区兴安落叶松人工林土壤为研究对象，通过阴燃炉实验，分析测定不同燃烧时间下的土壤温度和气体（CO₂、CO）释放量，及不同含水率（20%、30%、40%）对气体释放量的影响。
结果阴燃过程中土壤表层温度呈现先快速增加，然后保持平稳，最后快速下降直至熄灭的变化趋势；根据土壤表层温度变化特征，将阴燃过程分为点燃期、上升期、稳定期和熄灭期4个阶段，各阴燃阶段校正燃烧效率（MCE）均小于0.75；阴燃过程中CO₂平均释放量为316.23 mg/m³，CO平均释放量为101.25 mg/m³；阴燃过程中CO呈现持续性释放状态，CO₂呈现间歇性释放状态；燃烧时间对CO₂和CO释放量存在显著性影响，但CO₂和CO释放量不存在相关关系；不同含水率下，CO₂释放量呈现显著性差异（P ˂ 0.05），但CO释放量无显著性差异（P ˃ 0.05）。
结论根据阴燃中的温度和气体变化，阴燃在14 h 后出现向明燃转化的趋势，但由于土壤中可燃物含量下降，最终未转化为明燃；由于含水率升高导致土壤氧气含量下降和热量损失增加，因此CO₂释放量降低；在含水率20% ~ 40%的条件下，阴燃均可以维持蔓延传播，因此CO释放量无显著性差异。

Abstract:
Objective This paper simulates the smouldering combustion process, and discusses the characteristics of soil surface temperature and main emissions in order to provide scientific reference for smouldering combustion kinetics, spread mechanism and fire monitoring.
Method Taking the forest soil in the Larix gmelinii plantations of the Daxing’an Mountains as the research object, the temperature variation, main emissions and the effect of moisture content (20%, 30%, 40%) on emissions were analyzed by the results of smouldering furnace experiment.
Result The soil surface temperature firstly increased rapidly, then remained stable, and finally decreased rapidly until extinguished during the smouldering combustion process; according to the characteristics of soil surface temperature, the smouldering combustion was divided into four stages, i.e. ignition stage, rise stage, steady stage and extinguishing stage, and the modified combustion efficiency (MCE) of each smoldering stage was less than 0.75; the average concentration of CO₂ was 316.23 mg/m³, and the average concentration of CO was 101.25 mg/m³; in the smouldering combustion process, CO₂ emission was intermittent, but CO emission was continuous; combustion time had a significant effect on CO₂ and CO, but there was no correlation between CO₂ and CO; there was significant difference between the concentration of CO₂ under different moisture contents (P < 0.05), but there was no significant difference between the concentrations of CO (P > 0.05).
Conclusion The smouldering combustion shows a trend of conversion to flaming combustion after 14 h, according to the temperature and emission variation during the smouldering furnace experiment, but the combustion burnt out in the end for the decrease of combustible content; the concentration of CO₂ decreases with the increase of water content, resulting from the decrease of oxygen content and the increase of heat loss; smoldering combustion could maintain spread with moisture content of 20%−40%, so the concentration of CO has no significant difference.

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