爆炸下限临界浓度丙烷-空气混合过程及可燃性研究

摘要

Propane is one of the major constituents in petroleum gas,and its concentration distribution and flammability in the air is the basis of safety measures for petroleum gas.The influence of concentration distribution on the flammability of the propane-air mixture was analyzed using numerical simulation and experiment.The FLUENT,a computational fluid dynamics (CFD)software,was adopted to simulate the three-dimensional gas mixing process and the combustion process at a low flammability limit in non-adiabatic vessels with length-to-diameter ratios (L/D )of 1,3,5 and 7,respectively.The results show that the concentration distribution of the propane-air mixture is inhomogeneous by gravity,and the concentration distribution is the prime cause of the spark location affecting the combustion behavior of the propane-air at a low flammability limit.With the increase of the length-to-diameter ratio,the peak overpressure decreases.%丙烷是液化石油气的主要成分之一,爆炸下限的丙烷-空气浓度分布及其可燃性是液化石油气安全技术措施的基础.采用Fluent软件,建立三维数学模型,在长径比分别为1、3、5和7的容器内,模拟了爆炸下限的丙烷-空气混合过程和燃烧过程,分析了爆炸下限的丙烷-空气不均匀分布时对混合气体燃烧的影响.实验数据验证了该数值模型的合理性.在重力作用下丙烷-空气浓度分布不均匀,长径比增大,丙烷浓度梯度增大.浓度分布不均匀导致不同的点火位置对爆炸下限丙烷-空气燃烧有影响.容器长径比影响火焰传播,随着长径比增大,非均匀丙烷-空气混合气体超压峰值呈下降趋势,其超压峰值出现的时间变短.