高压高温甲烷-空气混合物爆炸极限试验

Experiment on explosion limits of methane-air mixtures at high pressure and high temperature

通过室内试验,研究甲烷-空气混合物在0.1~20 MPa和25~100℃条件下的爆炸极限和理论临界氧含量。采用高能量的通电钨丝点火系统,按照逐步逼近法获取爆炸极限点。基于试验数据,建立甲烷-空气混合物的高压高温爆炸极限预测模型。结果表明:随着初始压力和温度升高,甲烷的爆炸下限降低,爆炸上限显著增加,爆炸极限范围扩大,爆炸所需的最低临界氧含量降低,爆炸风险增加;甲烷-空气混合物在20 MPa和100℃条件下的爆炸极限为2.87%~64.40%,爆炸所需理论临界氧含量可降低至5.74%。爆炸上限处为贫氧状态,反应后有CO生成,爆炸下限处为富氧状态,反应产物多为CO2。

The explosion limits and theoretical critical oxygen volume fraction of methane-air mixtures at high pressure(up to 20 MPa) and high temperatures(up to 100 ℃) were measured in the laboratory via explosion experiments. Electrically powered tungsten wires with high ignition energy were used as ignition sources, and an approximation method was adopted in the determination of the explosion limits. Based on the experimental data, a high pressure and high temperature explosion limit prediction model for methane-air mixtures was established. The experimental results indicate that as the initial pressure and temperature increase, the lower explosion limit(LEL) of methane in air is slightly reduced, while the upper explosion limit(UEL) is significantly increased, and the theoretical critical oxygen volume fraction is gradually reduced. The explosion limits of methane arevaried linearly and logarithmically with temperature and pressure, respectively. The explosion limit of methane-air mixtures at 20 MPa and 100 ℃ is 2.87% to 64.40%, and the theoretical critical oxygen volume fraction is as low as 5.74%. In addition, at near the UEL points, some CO can be generated after the explosion reaction due to lack of oxygen, while at near LEL, the reaction products mostly consist of CO2 since oxygen is sufficient in the gas mixture.