Small scale experiments on boiling liquid expanding vapor explosions: Vessel over-pressure

The boiling liquid expanding vapor explosion (BLEVE) is a type of physical explosion that has caused massive damage in the petrochemical industry. In this paper, a study has been made of the conditions that could lead to a BLEVE. A device was built to simulate the occurrence of suddenly initiated release through a top orifice. As there is some danger in using liquefied petroleum gas (LPG) in the experiments, water was used as the test fluid. The change of pressure and temperature was measured during the experiment. It was determined that two pressure peaks result after the pressure is released: the first pressure peak seems to occur because of the vapor pressure caused by the swelled two-phase layer after the initial venting, the second pressure peak is possibly due to a dynamic impact or ‘liquid hammer’ and is maintained by bubbles collapse or something like cavitation at the surface of the inner wall of the head space that occurs with the ejection of two-phase flow.Liquid heights, orifice size, and the degree of liquid superheating all have differing influence on the magnitude of the measured over-pressure; the greater the degree of liquid superheat, the stronger the over-pressure; smaller opening areas delay and reduce the magnitude of the first over-pressure; at fill levels between 60% and 80%, the impact pressure appears more violent than with other fills.