Validated predictive capabilities of flashing liquid models
Hazardous situations can occur during a wide variety of industrial processes operating at high pressure as a result of human error or simple equipment failure. Among the accidental events, flammable pressurized liquid submitted to instantaneous release to ambient conditions is most frequently reported. This is known as flashing release and can be very violent,sometimes even explosive and may injure people and damage property near the source. Of specific interest in the effective management of risk associated with flashing liquids are the mathematical models and predictive computer codes, which may be applied to such releases. While there are many models available to embody an adequate understanding of the processes involved and predict consequent hazards, only a few have been validated for the unique conditions found in the chemical industry. A systematic and scientific validation of the simulation models developed within FLIE project, partially funded by the European Commission, was undertaken by the University of Hertfordshire, member of the project's consortium. The aim of this study was to determine whether current modelling approaches of flashing liquid releases using the Computational Fluid Dynamics (CFD) model's tools were consistent with established guidelines and protocols. Furthermore, sub-models developed for other industrial applications, where similar fluid processes prevail, were considered for their ability to reproduce the mechanism of flashing jet's subsequent two-phase dispersion. Particular emphasis was placed on the sub-processes of flash atomisation, droplet transport and rain-out downstream. With regard to the determination of the conditions of flashing release, evaluation of the existing theoretical approaches provided guidance for identifying the appropriate model for the critical flow modelling. The selection relied on data sets generated during laboratory and full scale experiments conducted in the frame of FLIE project. Better source models will contribute to improved predictive tools for the assessment of the hazard in the case of accidental release of flammable liquids. Enhanced prediction capabilities of flashing jets' models will also lead to direct application of the research in the operation and design of safer industrial plants handling flammable substances.
