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

Monitoring SO2 emission at the Soufriere Hills Volcano: implications for changes in erruptive conditions

FLWINinfo:eu-repo/semantics/publishe

A dynamic HAZOP case study using the Texas City refinery explosion

© 2016 Elsevier Ltd. The catastrophic explosion that occurred at Texas City on 23 March 2005 during the start-up of the raffinate splitter resulted in an estimated 15 deaths and 180 injuries. Since the incident, several studies have investigated the root causes of the disaster. Some contributing factors to the incident include wider organisational, process safety management, and human elements. There have also been some attempts to model the sequence of events before the incident, and the consequences of the resulting fires and explosions. This study provides a dynamic model of the sequence of events leading up to the incident and replicates the reported process variables during the isomerisation unit start-up on the day of the incident. The resulting simulation model is used as the framework for a dynamic hazard and operability (HAZOP) study

Consequence analysis of an explosion by simple models: Texas refinery gasoline explosion case

Accidents in petrochemical plants and oil refineries are quite destructive, due to the high reactivity of chemicals involved in them. An accident that occurred in the Texas City refinery, on March 23rd 2005, consisting on a vapour cloud explosion (VCE) that followed a gasoline release and caused 15 deaths, has been studied in terms of people vulnerability to overpressure and thermal radiation. With this aim, simple models (TNT, TNO Multi-Energy, BST) have been used in order to evaluate the effects of the explosion.Moreover, a thermal radiation model was used to estimate the damage caused by the heat released as consequence of the explosion. Finally, the Probit methodology was used to evaluate the vulnerability of persons. Although differences between the data derived from each of them existed, they all reproduced actual damages with a reasonable accuracy. The results reached let us say that the TNO and BST models predict with a reasonable accuracy the effects of the explosion that occurred. Furthermore, the use of simplified empirical models can be used for risk assessment

Rapid evaporation at the superheat limit

In an experimental investigation of the transient processes that occur when a single droplet of butane at the superheat limit vaporizes explosively, short-exposure photographs and fast-response pressure measurements have been used to construct a description of the complete explosion process. It is observed that only a single bubble forms within the drop during each explosion, and that the growth proceeds on a microsecond time scale. An interfacial instability driven by rapid evaporation has been observed on the surface of the bubbles. It is suggested that the Landau mechanism of instability, originally described in connection with the instability of laminar flames, also applies to rapid evaporation at the superheat limit. The photographic evidence and the pressure data are used to estimate the evaporative mass flux across the liquid-vapour interface after the onset of instability. The ;ate of evaporation is shown to be two orders of magnitude greater than would be predicted by conventional bubble-growth theories that do not account for the effects of instability. An estimate of the mean density within the bubbles during the evaporative stage indicates that it is more than one half of the critical density of butane. Additional interesting dynamical effects that are observed include a series of toroidal waves that form on the interface between the butane vapour and the external host liquid in the bubble column apparatus after the bubble has grown large enough to contact the outer edge of the drop, and violent oscillations of the bubble that occur on a millisecond time scale, after evaporation of the liquid butane is complete, that cause the disintegration of the bubble into a cloud of tiny bubbles by Rayleigh-Taylor instability

Liability Risk Assessment at Skarvik Port

The study focuses on a case of company X which owns an oil terminal and a depot in one of the Northern European countries. Company X's facilities are surrounded by the facilities of other oil companies. In case of an accident caused by company X there would be potential liability claims for property damage and business interruption. Insurance risk assessment is a well-developed approach for insurance of a company’s own property; it is not normally used for liability risks. This study suggests methodology for determination of liability insurance values. Based on the obtained results and calculations of replacement values, the worst case scenario for company X was chosen. A new methodology was developed to determine liability insurance values in cases like that, including the total limit - maximum insurance value that can be claimed

Ash plume properties retrieved from infrared images: a forward and inverse modeling approach

We present a coupled fluid-dynamic and electromagnetic model for volcanic ash plumes. In a forward approach, the model is able to simulate the plume dynamics from prescribed input flow conditions and generate the corresponding synthetic thermal infrared (TIR) image, allowing a comparison with field-based observations. An inversion procedure is then developed to retrieve ash plume properties from TIR images. The adopted fluid-dynamic model is based on a one-dimensional, stationary description of a self-similar (top-hat) turbulent plume, for which an asymptotic analytical solution is obtained. The electromagnetic emission/absorption model is based on the Schwarzschild's equation and on Mie's theory for disperse particles, assuming that particles are coarser than the radiation wavelength and neglecting scattering. [...] Application of the inversion procedure to an ash plume at Santiaguito volcano (Guatemala) has allowed us to retrieve the main plume input parameters, namely the initial radius $b_0$, velocity $U_0$, temperature $T_0$, gas mass ratio $n_0$, entrainment coefficient $k$ and their related uncertainty. Moreover, coupling with the electromagnetic model, we have been able to obtain a reliable estimate of the equivalent Sauter diameter $d_s$ of the total particle size distribution. The presented method is general and, in principle, can be applied to the spatial distribution of particle concentration and temperature obtained by any fluid-dynamic model, either integral or multidimensional, stationary or time-dependent, single or multiphase. The method discussed here is fast and robust, thus indicating potential for applications to real-time estimation of ash mass flux and particle size distribution, which is crucial for model-based forecasts of the volcanic ash dispersal process.Comment: 41 pages, 13 figures, submitted pape

Methods applied to investigage the major UVCE that occured in the TOTAL refiner's Fluid Catalytic Cracking Unit at La Mède, France

International audienceOn monday November 9, 1992 at 5:20 a.m. a major U. V.C.E, occured in the Gas Plant of the TOTAL refinery's Fluid Catalytic Cracking unit at La Mede, France. The origin was a 25 cm2 break in the 8" by-pass of the absorber stripper column cooler; an amount of about 15 tons of LPG and light naphtha was released within 10 minutes, covering an area of 14000m2 including Gas Plant, cryogenic, propene and Merox units before being ignited on the FCC main furnace