Comparative analysis of BLEVE mechanical energy and overpressure modelling

The mechanical effects of a BLEVE are overpressure and ejection of fragments. Although fragments reach much longer distances, peak overpressure can be very strong over a certain area. Diverse authors have proposed methodologies for the estimation of the explosion energy and peak overpressure from these type of explosions, based on different thermodynamic and physical assumptions. Here these methodologies are commented and compared. Their predictions, which show an important scattering, are checked by comparison with two sets of experimental data taken from the literature. The results obtained indicate that none of the models take into account Reid’s theory. The models based on ideal gas behaviour and constant volume energy addition, isentropic expansion and isothermal expansion give quite conservative (i.e., high) values of both energy released and overpressure, while those assuming real gas behaviour and adiabatic irreversible expansion give lower values, much closer to the real/experimental ones. The diverse uncertainty factors affecting the prediction of peak overpressure are also commented.Postprint (published version

The behaviour of vertical jet fires under sonic and subsonic regimes

Peer ReviewedPreprin

Els químics d'ahir: Arnau de Vilanova i un dels seus tractats d'alquímia

Postprint (published version

Modelling Temperature Evolution in Equipment Engulfed in a Pool-fire

A method is presented to calculate the incident radiant heat ßux and the temperatures reached on any point of a tank surface when this tank is engulfed in a pool-Þre during the Þre transitory state (developing phase). ¹he method used to calculate the radiant heat ßux on the cylinder is based on a three-dimensional formulation and uses the deÞnition of a surface to establish the ßame contour (according to a rectangular pool) taking into account the temperature changes with height and time. ¹he results are compared to experimental data obtained with large scale pool-Þres of hexane and kerosene, and show a good agreement. Finally, some conclusions are derived.Peer ReviewedPostprint (published version

Environmental risk assessment of accidental releases in chemical plants through fuzzy logic

Environmental risk assessment is an essential element in any decision making process in order to minimize the effects of human activities on the environment. Unfortunately, in many occasions, environmental data tend to be vague and imprecise and as a consequence uncertainty is associated to any study related to it. Uncertainty in risk assessment may have essentially two origins: randomness and incompleteness. In this paper, fuzzy logic is used to manage this uncertainty in environmental data concerning accidental releases in chemical plants. The methodology developed allows assessing the environmental risk of such releases using a set of parameters treated with fuzzy logic. This method can be used as a powerful tool by both public authorities and plant managers to take decisions in situations where chemical releases can occur.Postprint (author’s final draft

A new procedure to estimate BLEVE overpressure

Several methodologies, based on different thermodynamic assumptions and requiring substance properties and thermodynamic data, have been proposed in the literature for the prediction of the mechanical energy released by a Boiling Liquid Expanding Vapour Explosion (BLEVE) and the associated overpressure. A new method, simple and easy to use, is presented which only requires the vessel filling degree and the temperature at failure as input variables to estimate this energy. The polynomial approach has been used to obtain the equation corresponding to the diverse substances most commonly involved in these explosions. The comparison of the predicted values with experimental data shows a good agreement.Peer ReviewedPostprint (author's final draft

Fire as a primary event of accident domino sequences: The case of BLEVE

The domino sequences found in major accidents have been analyzed for a large set of cases (330); the first event triggering the domino effect was an explosion or a fire, both with approximately the same contribution; the same proportion has been found when all domino effect steps were considered. Although fire effects usually reach a distance much shorter than those of an explosion, as fire is the most frequent major accident it is often found as the first step of domino sequences. This is especially true in the case of BLEVEs. Both in fixed plants and in the transportation of hazardous materials, in the event of a fire, if flames affect a vessel and the fireproofing layer has been damaged, a BLEW can occur at any moment 127 BLEW accidents involving domino effect have been analyzed. It has been found that fire is significantly more frequent than explosion, both in triggering the domino effect sequence and in intermediate steps. The time to failure can range from 1 min or even less up to several hours, an aspect that should be very important for the management of the emergency. A set of conclusions are inferred from this survey. (C) 2015 Elsevier Ltd. All rights reserved.Postprint (author's final draft

Thermal and geometrical features of jet fires

Abstract: In many severe accidents involving explosions or large fires, jet fires have been the first step of a domino effect sequence: a recent historical analysis has shown that among the accidents registered in the data bases, in approximately 50% of the cases in which it was a jet fire it caused another event with severe effects. However, the knowledge of jet fires essential features –behaviour, effects– is still rather poor. In this communication, the results obtained with relatively large jet fires (with flame length up to 10 m) are discussed. The fuel was propane, and both sonic and subsonic jet exit velocities were obtained from different outlet diameters. The distribution of the temperatures of the flame main axis was measured with a set of thermocouples. The jet fires were filmed with a videocamera registering visible light (VHS) and a thermographic camera (IR). The main flame geometrical features were analyzed as a function of the jet main variables, as well as the thermal effects (thermal radiation intensity as a function of distance).Postprint (published version