不同湿度和近爆炸下限条件下甲烷-空气混合物爆炸特征

Explosion characteristics of methane-air mixture near lower explosion limit at different relative humidities

为了研究不同湿度条件下低浓度甲烷-空气混合物爆炸特征,设计了饱和湿空气发生及储存装置,对管路、气囊和爆炸腔体进行温度控制和流量调节,实现了不同相对湿度的甲烷-空气混合气体的配置。采用20 L球形爆炸测试装置,分析不同相对湿度、甲烷浓度对混合物的最大爆炸压力、最大压力上升速率、爆炸下限及层流燃烧速度的影响。结果表明,随着相对湿度增大,最大爆炸压力和最大爆炸压力上升速率逐渐下降,且呈一定的线性关系。混合气体相对湿度从27.7%增大到80.1%时,甲烷爆炸下限从5.15%上升到5.25%,上升率1.9%,层流燃烧速度随相对湿度的增大也呈线性降低趋势。在本文条件下,相对湿度对甲烷-空气混合物的爆炸影响较小,这主要与常温常压下水蒸气的饱和分压力较低有关,但在高温高压时仍需考虑水蒸气含量的增大对混合气体爆炸特征的影响。

To explore the explosion characteristics of methane-air mixtures with low concentration of methane at various humidities,a device for producing and containing water-saturated air was developed.The temperature and flow of pipes,air bag and explosion vessel were controlled to obtain methane-air mixture with variable humidity.The 20 L spherical explosion vessel was employed to analyze the effect of relative humidity and methane concentration on methane explosion characteristics(i.e.,maximum explosion pressure,maximum rate of pressure rise,lower explosion limit and laminar burning velocity).It is concluded that the maximum explosion pressure and maximum rate of pressure rise show a linear decrease with an increasing value of humidity.As the humidity of gas mixture changes from 27.7%to 80.1%,the lower explosion limit of methane in air increases from 5.15%to 5.25%with a rising rate of 1.9%.The laminar burning velocity performs a similar linear downtrend with the increase of relative humidity.Under the given circumstances,the relative humidity has no significant influence on the explosion characteristic of methane-air mixture,which can be ascribed to the low value of partial pressure of water vapor at ambient condition.However,this influence cannot be neglected as the water vapor increases to a certain extent level at high temperatures and high pressures.