Analysis of the impact of wildland-urban-interface fires on LPG domestic tanks

Managing Wildland-Urban-Interface (WUI) fires is a challenging task due to the inherent complexity of the WUI environment. To ensure the success of strategies for the protection of population and structures, safety measures have to be implemented at different scales (landscape, community and homeowner). The present study is focused on the homeowner scale and deals with the threat related to the presence of LPG domestic tanks in a WUI fire scenario. Recent accidents have demonstrated that the risk associated with this type of installation is real, but often disregarded by residents. A methodology was developed, providing a set of indicators that may easily be compared with risk acceptance criteria, assessing whether the integrity of an LPG tank exposed to WUI fire scenarios is compromised or not. The methodology is applicable to a vast range of situations and at a different level of detail according to available data. A number of case studies were carried out, showing that WUI fire scenarios impacting on domestic LPG tanks complying with regulations currently adopted in several Mediterranean countries cannot be deemed safe. The methodology proposed represents an advanced tool to assist on safety distances sizing to be prescribed by standards, driving regulators towards better-informed decision-making. Peer Reviewe

Report on LPG infrastructure impact at the WUI microscale

Preprin

Cryogenic Hydrogen Storage Tanks Exposed to Fires: a CFD study

Hydrogen is one of the most suitable candidates in replacing heavy hydrocarbons. Liquefaction of fuels is one of the most effective processes to increase their low density. This is critical especially in large-scale or mobile applications such as in the maritime or aeronautical fields. A potential loss of integrity of the cryogenic storage equipment might lead to severe consequences due to the properties of these substances (e.g. high flammability). For this reason, this critical event must be avoided. The aim of this study is to analyse the behaviour of the cryogenic vessel and its lading when it is exposed to a fire and understand how to prevent a catastrophic rupture of the tank during this accident scenario. A two-dimensional computational fluid dynamic (CFD) analysis is carried out on a cryogenic liquid hydrogen (LH2) vessel to investigate its thermal response when engulfed in a fire. The model accounts for the evaporation and condensation of the substance and can predict the tank pressurization rate and temperature distribution. It is assumed that the vessel is completely engulfed in the fire (worst-case scenario). The CFD model is validated with the outcomes of a small-scale fire test of an LH2 tank. Critical indications on the dynamic response of the cryogenic tank involved in a worst-case accident scenario are provided. Tank pressurisation and temperature distributions of the case study can be exploited to provide conservative estimations of the time to failure (TTF) of the vessel. These outcomes represent useful information to support the emergency response to this type of accident scenario and can aid the selection of appropriate and effective safety barriers to prevent the complete destruction of the tank

Asset integrity in the case of Wildfires at Wildland-Industrial Interfaces

Wildfires are uncontrolled fires involving the combustion of wild vegetation. When a wildfire front approaches the Wildland-Industrial Interface there can be a serious threat for process and storage equipment items located at the plant boundary. Ensuring the integrity of such equipment prevents the fire from spreading inside the plant site and causing major accidents such as fire, explosion, and toxic gas dispersion. The provision of adequate clearance areas is paramount since the early stages of the plant design. Once the facility is built, the implementation of safety measures can protect industrial items and ensure tank integrity. A tailored methodology for the calculation of safety distances between wild vegetation and tanks accounting for the safety system was developed and applied to a case study. The outcomes provide useful information on the effectiveness of safety measures for the protection of industrial items exposed to wildfire

WUI state of the art and regulatory needs in Europe

The document summarizes the state of the art of the regulationsrelevant to WUI in Europe, providing an organized set of references to the specific regulatory documents. It is focused on three main relevant topics: i) fuel-reduced fringes; ii) Building codes and standards; iii)Wildland-Industrial Interface. Current regulations are analysed and compared, leading to the identification of important needs and limitations of the current European regulatory frameworkPreprin

Modelling pressure tanks under fire exposure: past experience, current challenges and future perspectives

CFD and lumped parameter models are available in the literature for the analysis of pressure tanks under fire exposure. The first type of models allows for a detailed representation of the phenomena occurring in the tank, providing accurate results in terms of pressurization rate and temperature distribution. However, they are computationally expensive and are currently unable to simulate PRV opening. Lumped parameter models run in very short time, but may lead to not conservative results. The present contribution provides an overview of the strengths and limitations of both approaches, highlighting the new challenges posed by the development of models for the analysis of cryogenic tanks exposed to fire

Main specifications of CFD codes for WUIVIEW activities

CFD simulations will be the core activity of the WUVIEW performance based fire safety analysis. The purpose of this document is to provide WUIVIEW partners with a general overview of the CFD codes to be used in the Action. The general simulation framework is described, particularly highlighting data inputs and scenario description requirements, to be developed in subsequent WUIVIEW WPs. This TN provides the technical foundations and main specifications of the databases to be designed within the WUIVIEW working program (ongoing action by UPC).Postprint (updated version

Asset integrity in the case of wildfires at wildland-industrial interfaces

Wildfires are uncontrolled fires involving the combustion of wild vegetation. When a wildfire front approaches the Wildland-Industrial Interface there can be a serious threat for process and storage equipment items located at the plant boundary. Ensuring the integrity of such equipment prevents the fire from spreading inside the plant site and causing major accidents such as fire, explosion, and toxic gas dispersion. The provision of adequate clearance areas is paramount since the early stages of the plant design. Once the facility is built, the implementation of safety measures can protect industrial items and ensure tank integrity. A tailored methodology for the calculation of safety distances between wild vegetation and tanks accounting for the safety system was developed and applied to a case study. The outcomes provide useful information on the effectiveness of safety measures for the protection of industrial items exposed to wildfire.Peer ReviewedPostprint (published version

Numerical simulation of LNG tanks exposed to fire

The increasing use of Liquefied Natural Gas (LNG) as a fuel for ships and vehicles poses relevant safety concerns, extended to the entire LNG supply chain and distribution network. Understanding the phenomena associated with the behavior of LNG tanks exposed to severe heat sources is thus a fundamental issue to identify potential safety-critical scenarios. The experimental data and modeling approaches currently available, mainly referring to small-scale pilot vessels, feature relevant limitations when extended to large-scale applications. In the present study, a two-dimensional non-equilibrium computational fluid dynamics model (2D CFD) of LNG tanks exposed to fire engulfing scenarios was developed. The 2D CFD model was validated against experimental bonfire data and was extended to simulate the behavior of large-scale vessels used in specific industrial applications, as the road transportation of LNG and the fuel supply of ships. A set of Key Performance Indicators (KPIs) was defined to support the safety assessment of LNG tanks, and to identify the potential transition to safety critical regions during fire exposure. The CFD results obtained allowed investigating the influence of operative parameters and geometry on the pressure build-up in the tanks, as well as on the transient evolution of complicating phenomena, such as the thermal stratification. The KPIs defined provide a useful support for the design of safety systems and for decision making in emergency response