具有体积分数梯度的连通装置甲烷-空气爆炸特性数值模拟

Numerical simulation of methane-air explosion in a connected device with volume fraction gradient

为了研究具有体积分数梯度的连通装置内甲烷-空气爆炸特性,以60 L圆柱体容器和20 L圆柱体容器通过3 m长,截面为0.035 m×0.035 m的方形管道而连接形成的容器管道连通装置作为研究对象,利用Fluidyn软件对均一体积分数的连通装置以及具有体积分数梯度的连通装置中甲烷-空气爆炸的特性进行了数值模拟。结果表明:连通装置中甲烷的均一体积分数为6.517%~8.067%时,并由大容器中心点火工况时,最大爆炸压力、最大爆炸压力上升速率、最高温度和最大速度,以及这些爆炸参数达到最大值时的时刻值随体积分数的变化约呈线性关系;连通装置大容器甲烷体积分数6.0%体积分数梯度为2.0%~8.0%且大容器中心点火时,最大爆炸压力、最大爆炸压力上升速率、最高温度和最大速度随体积分数梯度总体上呈现先增大后减小趋势;大容器中心点火时,最大爆炸压力位于小容器,最大压力上升速率位于管道1或管道2,最大速度位于管道3,速度值可达400~600m/s。本研究可为连通装置内可燃气体爆炸事故防控提供理论指导。

A connected vessel is a common typical chemical plant,and its explosion hazard is much higher than that of an independent vessel.In an actual explosion accident,the combustible gas volume fraction in the connected device presents a non-uniform state,and there is a volume fraction gradient.A connected device was chosen as the research object.The device was formed by connecting two cylindrical vessels with the volumes of 60 litres and 20 litres,respectively,through a square pipe as long as 3 meters,with a cross section of 35 mm×35 mm.To explore the methane-air explosion characteristics in the connected device with combustible gas volume fraction gradient,the Fluidyn software was applied to numerically simulate the methane-air explosions in the connected devices with uniform and non-uniform combustible gas volume fractions,respectively.The results show as follows.When the volume fraction of the methane in the connected device is uniform and ranges from 6.517%to 8.067%and the ignition is located in the center of the large vessel,the maximum explosion pressure,the maximum explosion pressure rise rate,the maximum temperature and the maximum velocity as well as their arrival times change linearily with the volume fraction of the methane.When the volume fraction of the methane in the large vessel of the connected device is 6.0%,the volume fraction gradient of the methane is 2.0%to 8.0%,and the ignition is located in the center of the large vessel,the maximum values of the parameters,including explosion pressure,explosion pressure rise rate,flame temperature and velocity,increase firstly and then decrease with increasing volume fraction gradient.When the ignition is located in the center of the large vessel,the maximum explosion pressure is in the small vessel,the maximum pressure rising rate is in the pipe connected to the large vessel,and the maximum flame velocity is in the pipe connected to the small vessel,and the flame velocity can reach 400-600 m/s.The research results can provide a theoretical guidance for preventing and controling combustible gas explosion accident in connected devices.