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Common Sense Emergency Response
Published in Robert A. Burke, Common Sense Emergency Response, 2020
This acronym stands for the following phenomenon: Boiling Liquid, Expanding Vapor, Explosion. BLEVE is a violent explosion and tank failure that breaks the tank into pieces that are rocked several thousands of feet away from the blast center (Figure 4.71). BLEVE is the second leading cause of death to emergency responders dealing with hazardous materials. This phenomenon in my opinion only applies to liquefied compressed gases shipped, stored, and transported in pressure containers where the liquid exists in the container above its boiling point. If you look at the explanation of BLEVE as it was originally put forth it really explains the concept. Boiling liquid, the liquid in the container is there above its boiling point and kept in the container by pressure. The boiling liquid is a liquefied compressed gas, not a typical liquid. Expanding Vapor, when the pressure is released from the container all of the liquefied gas instantly returns to the gas state. No liquid is left in the container. This process occurs explosively. Fire may occur or a fireball if the gas released is a flammable gas and it reaches an ignition source. Hazards that are presented by this scenario are much different and more severe than a fire and release of product involving a liquid container. We are talking about common hazardous materials like propane, butane, and LPG in terms of flammability. Nonflammable liquefied containers can also BLEVE, such as anhydrous ammonia, chlorine, and others. These are not “exotic” materials and are found in most communities.
Fundamentals of Source Assessment
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
A special kind of explosion, the nightmare of every fireman and emergency responder, is the BLEVE (pronounced BLEH–vee). The acronym BLEVE stands for Boiling Liquid Expanding Vapor Explosion, which is descriptive of the chain of events leading to the explosion. An external flame or radiant heat from an external fire impinges on the surface of the tank, heating the liquid contents and raising its vapor pressure. As the walls heat up, the structural integrity of the tank is weakened. Eventually, the liquid reaches its boiling point and the vapor pressure is atmospheric or greater depending on whether some vapor escape rapidly enough. When the last of the liquid is boiled off, the vapor is superheated and, with the right amount of oxygen, an explosive mixture is created. The tank then becomes a huge bomb. The BLEVE itself is the explosive vaporization of the remaining vessel contents, often followed by the combustion of the vaporized cloud that preceded it. If you have never seen a BLEVE , several good videos are available from training video vendors and fire departments. First, the tank explodes, then, depending on whether the liquid is combustible, the vapor cloud explodes. Double whammy of catastrophic proportions. As said earlier, BLEVEs are every emergency responder’s worst nightmare.
Identify and Assess Process Hazards
Published in James A. Klein, Bruce K. Vaughen, Process Safety, 2017
James A. Klein, Bruce K. Vaughen
Major types of explosion events include [34,35]: Vapor cloud explosion (VCE) – large flammable releases that occur above the flash point of materials in the cloud, which when ignited, result in damaging deflagrations depending on the size and location of the cloud, reactivity of the fuel, and degree of confinement and congestion.Boiling liquid expanding vapor explosion (BLEVE) – rapid release and vaporization of volatile, flammable materials usually due to external heating of a closed container (such as a drum or vessel) leading to catastrophic container rupture and vapor ignition.Vessel burst – catastrophic failure of a vessel caused by a rapid increase in pressure, possibly resulting from uncontrolled heating, chemical reaction, failure of pressure instrumentation and devices, or internal deflagration within the equipment.
Parametric studies on hydrocarbon fireball using large eddy simulations
Published in Combustion Theory and Modelling, 2019
Ashish V. Shelke, Bhuvaneshwar Gera, Naresh K. Maheshwari, Ram K. Singh
Small-scale fireball experiments include soap bubble experiments in which a spherical gas-air mixture contained by a thin envelope at ambient pressure was released. The released gas was then ignited by a source to form a fireball. The second category includes boiling liquid evaporating vapour explosion (BLEVE). The flask containing liquefied fuel was ruptured when vapour pressure reached above its design limit value. This causes the release of vapour released to form a fireball. The behaviour of fireball has been studied by measurement of fireball diameter, lift-off time, combustion duration and final height using high-speed cameras. The radiation and temperature were measured by using radiometers and thermocouples or by fireball colours.
Thermodynamic properties and explosion energy analysis of carbon dioxide blasting systems
Published in Mining Technology, 2019
Bo Ke, Keping Zhou, Chaoshui Xu, Gaofeng Ren, Tingting Jiang
This article presents the results of an experimental study of carbon dioxide blasting. Based on the results, the following conclusions can be drawn: The rate of temperature change increases as the initial density of CO2 decreases and the temperature rises faster when the initial temperature is higher. The graph of temperature variations appears as a concave exponential curve initially, then rapidly increases linearly, followed by a gentle increase.The effect of the initial density of CO2 on isochoric heat capacity appears to be significant. The smaller the initial density, the larger the peak specific heat capacity at the critical temperature. The variation of the specific isochoric heat capacity can be used to divide the temperature curve into four stages. The specific isochoric heat capacity and its rate of change determine the increasing rate of temperature.Based on the pressure curve of CO2 blasting, the process can be divided into three stages: the pressure rise stage, the pressure release stage and the pressure recovery stage. The period of time for the pressure rise stage is about 0.026–0.086 s, and that for the pressure release stage is about 0.00018–0.00026 s. In terms of the mechanism of pressure response and phase transitions of CO2 within the tube, the tube is initially filled with high-density fluid and low-density gas. When the heater is activated, the heat is transmitted to the CO2 and temperature and pressure increase, causing the CO2 to enter the supercritical state. When the internal pressure exceeds the strength of the rupture disc, the disc breaks, causing the high-pressure supercritical CO2 to be released from the tube with a rapid depressurisation. The entire process is termed the Boiling Liquid Expanding Vapour Explosion (BLEVE).Using the Span and Wagner CO2 EOS and the thermodynamics of explosion, the proposed method can be used to calculate the explosion energy of CO2 blasting systems. As discussed above and demonstrated using figures measured in our experiments, the calculation results are more accurate for carbon dioxide blasting systems.