BLEVEs - Sample Problems

In this chapter, applications of the calculation methods used to predict the hazards of BLEVEs, as described in Chapter 6, are demonstrated in the solution of sample problems. Fire-induced BLEVEs are often accompanied by fireballs hence, problems include calculation of radiation effects. A BLEVE may also produce blast waves and propel vessel fragments for long distances. The problems include calculations for estimating these effects as well. Calculation methods for addressing each of these hazards will be demonstrated separately in the following order radiation, blast effects, and fragmentation effects. 

The radiation hazard from a BLEVE fireball can be estimated once the following fireball properties are known  

For each of these properties, data and calculation techniques are available. A summary is presented below. 

Hasegawa and Sato (1977) showed that when the calculated amount of flashing evaporation of the liquid equals 36% or more, all of the contained fuel contributes to the BLEVE and eventually to the fireball. For lower flash-off values, part of the fiiel forms the BLEVE and part of it forms a pool. It is assumed that if the flashing evaporation is lower than 36%, three times the quantity of the flashing liquid contributes to the BLEVE. 

For prediction purposes, the amount of gas in a BLEVE can be taken as three times the amount of flashing liquid up to a maximum of 100% of available fuel. 

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