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1. Introduction
Liquefied-pressure gases (LPG) are substances such as propane, butane and chlorine, which are transported and stored in the liquid phase in tanks under sufficiently high pressure. If, for any reason, such a tank is damaged, an abrupt pressure drop may release enormous quantities of evaporating gas and energy, which has a destructive effect on the tank and its surroundings [1]. The degree of hazard depends on many factors such as the mass of substance released, the rate of gas release, physico-chemical properties of the substance in the moment of its release, flammability and toxicity of the medium flowing out. Sometimes the outflow of liquefied-pressure gas is calm and does not present a menace to the environment. It happens, however, that its results can be disastrous. The most dangerous is a boiling liquid expanding vapor explosion (BLEVE). A destructive character of such explosions is usually related to an abrupt transition of the media from liquid to gas phase [2].

1 引言

液化压缩气体（液化石油气）是物质如丙烷，丁烷和氯，其运输和存储足够高的压力下舱内的液相。如果，以任何理由，这种坦克损坏，突然的压力降可以释放大量的蒸发气和能量，这对坦克和其周围环境的破坏作用[ 1 ]。危害程度取决于诸如物质质量的因素很多，释放气体的速率，在发布的那一刻的物质的物理化学性质，在介质流出的可燃性和毒性。有时液化压力气体的流出是平静的，不构成威胁的环境。它发生，然而，其结果可能是灾难性的。最危险的是一个沸腾液体扩展蒸气爆炸（BLEVE）。这样的爆炸破坏的特点通常是由液气相[ 2 ]的媒体突然转变相关。

2. BLEVE phenomena
The BLEVE occurs when a liquid of temperature higher than its boiling point under normal pressure suddenly flows out. This leak is caused by an extensive damage of the tank, usually in several places [3]. The tank can be unsealed due to the action of an external fire source, overfilling of the tank, weakening of wall material caused by corrosion or mechanical damage as a result of a car crash, for example.

2 BLEVE现象

BLEVE发生时，液体的沸点较高的温度比在正常压力突然流出。这个漏洞被箱广泛损伤，通常在几个地方[ 3 ]。坦克可以归因于外部火源的作用是密封的，如果罐，削弱墙体材料由于腐蚀或机械损伤引起撞车，例如。

The most common type of BLEVE occurs when a pressure vessel that is partially filled with liquid is exposed to a fire[4]. Because the vessel is subjected to high heat flux from a fire, temperature of the liquid starts to increase. The pressure in the tank increases due to the increased va porization rate. The thermally induced stresses in the tank shell, heat weakened tank and high internal pressure combine to cause a sudden, violent rupture of the tank. Most of the remaining liquid vaporizes extremely rapidly due to the pressure release and the rest atomizes to small drops due to the force of the explosion. Because thermally induced BLEVE’s result from exposure to fires, it follows that the tank contents, if flammable, once released by the tank failure, will be ignited. Therefore, this type of BLEVE generally results in a large fire or fireball.

If a pressurized tank containing a liquefied gas and its vapor is suddenly depressurised, the equilibrium between the liquid and vapor will be shifted that some of the liquid will change to vapor. If this depressurization occurs due to tank failure, the phase change from liquid to vapor may appear so rapidly that the force from expansion of the vapor will cause the liquid and vapor to be propelled violently in all directions. This behavior is often the part of the ther mally induced BLEVE. The mechanism of the BLEVE phenomenon has not been fully ide本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。