Boiling Liquid Expanding Vapor Explosion

BLEVE (Boiling liquid expanding vapor explosion) is a rapid, explosive release of energy, which occurs when a container that is closed with heated; pressurized, and super-heated water suddenly bursts. BLEVE happens when a tank is exposed to sustained heat the liquid within the tank is forced to boil or vaporize resulting in increased pressure in the tank, which activates the release valve to open to prevent overstretching of the tank releasing the excess weight, which closes after pressure has been reduced in the tank. With continued heating, the pressure builds again as the liquid absorbs the heat allowing the tank metal to remain at the same temperature. With the continued operation of the release valve, the liquid level drops exposing a greater area of the tank to the apex of the heat with the flames infringing on the vapor space making the temperature of the metal that was covered by the liquid rise. Because of the vapor pressure in the tank, the metal structure begins to weaken stretch, and tear. As the tank comes after both quantities of vapor and liquid quantities are released in large amounts in a powerful explosion. The heat generated is high enough to ignite combustibles and all the inflammable materials around the areas of its explosion. The ignition of flammables causes devastation to the environment and even loss of life because of its high heat wave. The mass of burning vapor that is expanding including the portion of the ground forms a fireball as it rises from the field. This fireball produces radiant heat, which is sufficient to ignite the majority of the combustibles that are within the surrounding area which burn more than one thousand feet from the fireball. Flammable gases such as methane, propane, butane, and octane have a combustion explosion effect because whenever these gases come in contact with the atmosphere, there is potential for a combustion explosion. The explosion has impacted both the inside environment and the outside environment. The interior climate is affected by the amount of gas that has leaked before it ignites. If the leak does not result in an explosion, there are possibilities of toxic hazard, cryogenic hazard, and an asphyxiant hazard. This hazard results in environmental poisoning which bears adverse effects on man and the environment when they come in contact with these biohazard materials. The loss of containment is often because of the catastrophic failure of the container that is holding the super-heated water. The actual amount of force released by BLEVE relies on the pressure and temperature of the water that is inside the tank (Ren et al., 2017). Kingman was in a catastrophic state of a boiling liquid expanding vapor explosion on July 5, 1993, which killed more than eleven firefighters who tried to control the flames. An explosion occurred because of a fire that broke out as propane was being taken from a railroad car to the storage tanks. A leak was detected in the fittings, and an attempt to correct the situation was made by fitting a more massive wrench. The gas ignited turning the tanker into a vast fireball that engulfed the operators as they rose more than seventy feet above the ground. The explosion sent flames and debris together with the three-ton end of the half-inch metal tanker, which landed a quarter mile down the track. The flaming propane ignited buildings that were around it as victims were being rushed to the hospitals. The total material damage was valued to exceed one million dollars as it chatted everything that was near the tanker. Asa result of the Kingman disaster, procedures that are standardized have been rolled out to handle BLEVE throughout the country to be used by the firefighting department to fight these massive flames in case they reoccurred in the future. The explosion was explicitly caused during the transfer of propane from a Doxol railroad car to the storage tank near Andy Avenue when a worker attempted to tighten the leak of propane by hitting the wrench with another with a hammer, which caused a spark that ignited the leaking gas. The burning propane gas that was escaping from the valve on the railroad heated the liquid propane, which was inside the tank increasing the pressure in the tank, which in turn grew the leak and the fire, further heating the tank. BLEVE does not need to be a chemical explosion. However, if a substance is flammable, it is subject to a BLEVE as it is subject to heating that is intense either from external sources of heat which can be caused by the vessel, which raptures, or from a source that is internal from the friction of the skin. The friction causes flammable materials to ignite which results in an explosion, which is secondary as the primary cause is BLEVE. The blast has a devastating effect once it is exposed to a flammable substance such as propane. BLEVE can also occur in a non-flammable material such as water, liquid nitrogen, cryogenics, and refrigerants as they are not usually considered a chemical explosion. In the case of liquefied gases, BLEVE is hazardous because of the rapid cooling because of rapid cooling which is either because of the absorption of the evaporation enthalpy or because of the asphyxiation when the large volumes of gas are generated and not rapidly dispersed, and the toxic nature of the gases that are produced. 

Reference  

Ren, J. J., Ye, Z. X., Fan, S. Q., & Bi, M. S. (2017). Analysis of the explosive boiling process of liquefied gases due to rapid depressurization. Journal of Loss Prevention in the Process Industries , 49 , 845-851. 

SLCFireTech. “BLEVE Video from the 1970's.” YouTube , YouTube, 17 Apr. 2014, www.youtube.com/watch?v=0W88v5tMWJ0.