Development and validation of models for accident scenario following the spill of hazardous substances from pipelines

The releases of hazardous substance from pressurised pipelines are of particular interest due to the different scenarios that may occur following the loss of containment. These may have different causes, as accidental release, corrosion, etc. In such cases the release of flammable substances can lead to different scenarios as Fires, Explosions and Environmental pollutions. The severity of such scenarios can increase due the "Domino Effect" that will affect also other equipment or near unit operations, potentially causing a cascading event. For these reasons an accurate methodology is necessary in order to estimate the consequences and the evaluation of the possible hazards coming from those scenarios. In this work a CFD software developed at the University College London (UCL) called PipeTech was used to predict the depressurization parameters (Temperature, Pressure, etc.) and the outflow following the rupture of a pipeline, as well as to assess the hazard coming from the Jet Fire and the Pool Fire. In particular, an initial validation, against some experimental data and another commercial software Phast (DNV GL), of the Jet Fire and Pool Fire models implemented in PipeTech was performed. Moreover, an evaluation of the effect of some main parameter (pressure, tilt angle and orifice diameter) were taken into account to evaluate how they affect the incident radiation coming from the Jet Fire. With the aim to upgrade the Pool Fire model implemented in PipeTech, a new model based on correlations found in literature is described, in which the flame is considered as to have two different emitting zones: a lower and luminous part and an upper partially obscured part due to the smoke envelope that emits with distinctive Surface Emissive Power, thus affecting in different way the incident radiation coming from a Pool Fire, Especially in the region very close to the flame. This upgrade was validated against Phast v8.2 and some experimental data present in literature.