基于PHAST软件的站场冷放空燃爆事故模拟分析

为提高天然气长输管道阀室冷放空作业的安全性,针对冷放空作业中的意外闪燃、爆燃事故现象,基于UDM模型并运用PHAST计算机软件,先模拟了泄放气体发生闪燃事故的影响域,分析冷放空气体闪燃范围随风速、大气稳定度、放空压力及放空速率4种影响因素而变化的趋势;后又讨论了放空速率对爆燃超压伤害范围的影响。结果表明:闪燃范围随风速、大气稳定度、放空压力及放空速率增加而递增,后两者对其影响较大,应重点关注并控制;在模拟工况下,最远轻伤距离达60 m,因此在实际工程中,控制放空速率对减轻意外燃爆事故的后果极为重要,应注重对放空作业参数的调整。

Simulated analysis of the cold venting deflagration accidents in the gas stations via the PHAST software

The present paper is aimed at presenting a simulated analysis of the cold venting deflagration accidents in the gas stations via the PHAST Software so as to improve the safety of the ventilation operation in the long distance natural-gas pipeline transmission. In the said simulated analysis,the flash fire dispersion range of the cold venting is supposed to be simulated with a so-called UDM model and the PHAST software. For the purpose of simulation,we have identified and determined the developmental trend of the flash fire envelope of the cold-vented gas with such factors as the wind speed,the atmospheric stability,the venting pressure and the venting rate being taken into consideration. And,then,we have managed to draw a curve of the flash fire envelope to show the variation trends of all the influential factors. The simulation results we have gained indicate that: the flash fire envelope tends to increase with the increase of the wind speed,on the condition of the stable atmosphere,the venting pressure and the emptying rate,with the latter two producing a greater influence on the wind speed. That is to say,it has to be taken as the focus to be controlled. What is more,if and when the rate exceeds 20 × 104 m3 /h,it is also necessary to take into account the heat ventilation. Therefore,it is also essential to discuss and analyze the impact of the venting rate on the damage degree of the deflagration overpressure. Just for the said purpose,it is also needed to edit and compose a table of the damage degrees or destructive impacts of the explosion overpressure on the human body and the explosion overpressure curve of venting rate,as well as the explosion influential range. In the simulated operating conditions, it is known that the farthest light-ray injury distance is about 60 m long. Seeing the fact,it is of extreme importance to control the initial venting pressure,the amount of the ventilation gas and the emptying rate so as to mitigate the consequences of the accidental flash-explosion accidents in the actual project. And,in turn,the workers in charge of the blast experiment should be recommended to focus their attention on the regulation of the venting parameters,so as to provide for the needed technical supports for the safe operation of the cold-ventilation. Besides, it should be an effective way,too,to strictly control the fire source to get rid of any flash and blast accidents.