BLEVE: a New Approach to the Superheat Limit Temperature

Several methods proposed for calculating the value of the superheat limit temperature were analysed. The results obtained indicate that the procedures based on the thermodynamic stability approach introduce a significant uncertainty into the final values, depending on which equation of state is used. We propose a new approach based on the energy balance in the initial liquid mass just before the explosion. The temperature obtained using this method, Tsl-E, corresponds to the situation in which the energy transferred adiabatically between the cooling liquid and the vaporising liquid fractions is at its maximum. This leads to a minimum content of energy in the remaining liquid. Although these two approaches are equivalent-the procedures based on the thermodynamic stability approach use also the minimum energy state as a criterion-the new proposed method only uses the properties of the substance to obtain Tsl-E. Thus, Tsl-E represents the behaviour of each substance as a function of its molecular structure, while this influence is lost if a simple equation of state is used. Finally, some considerations are made on the limitations of the superheat limit temperature as a criterion for establishing whether an explosion is or is not a BLEVE.