Rachida Hamzi

Industrial fire simulation and uncertainty associated with the Emission Dispersion Model

The use of numerical modeling in the field of industrial fire accidentology has become common nowadays and this tendency is expected to increase with the development of performance simulation tools. Despite the constant development of fire modeling tools, the current state of the art is not yet able to accurately predict fire phenomena. This gap between the reality and simulations is probably due to the presence of some level of uncertainty, which may occur from the meteorological inputs, diffusion assumptions, plume dynamics, or emission production. To cope with the presence of uncertainties in the input data, we propose an uncertainty analysis enabling to avoid as much as possible bad decisions that may have a large impact in domains such as safety. In this study, we are interested in the uncertainty propagation related to NO2 atmospheric dispersion resulting from a crude oil tank fire. Uncertainties were defined a priori for each of the following input parameters: wind speed, NO2 emission rate, and viscosity and diffusivity coefficients. For that purpose, a Monte Carlo approach has been used. In order to evaluate the importance of the considered parameters on the NO2 dispersion, new sensitivity indicator has been developed. The obtained results showed that the viscosity coefficient and the wind speed are the most significant input parameters with respect to NO2 concentration near to the source of fire, while the wind speed and the initial concentration are the important parameters for distant areas.

A Quantitative Risk Assessment Approach for the Dynamic Environmental Impact of Fire

This paper proposes a quantitative risk assessment approach to assess the frequency of an accident and its measurable consequences (for human, property and environment). The illustration of the proposed methodology is made on a refinery gasoline storage system with a high potential of fire risk, where the major initiating event is the overfilling of the gasoline tank. The objective of the study is to estimate the frequency of the tank overfilling as well as those relating to the likely consequences regarding the response of the different safety barriers in order to be compared to a threshold value (tolerable frequency). The consequences are quantified by taking into account the toxicity of gases (atmospheric dispersion) and liquid (effect on the soil), the thermal radiation (heat) and the overpressure (explosion blast force). To improve the storage system safety and thus reduce the associated risk level, several measures have been proposed.

Contribution of the lessons learned from oil refining accidents to the industrial risks assessment

Purpose The purpose of this paper is to employ lessons learned from the industrial accidents in Skikda refinery during the period from 2005 to 2016 as input data for the numerical simulation of risk consequences to identify the exposed areas to the various effects of industrial accidents. Design/methodology/approach In order to assess how the lessons learned can contribute to modeling the accidents effects in the refining activities, this paper presents a combined statistical/dynamic approach that combines two main tools, namely, lessons learned from petroleum refining in Algeria and Areal Locations of Hazardous Atmospheres software. Findings The results showed that fire is the most frequent accident at Skikda refinery that is mainly caused by equipment failures with a frequent involvement of crude oil and LNG. The NO2 toxic effects are unacceptable. This means that in the case of a similar accident, the entire population will be exposed to an intolerable concentration of NO2. Therefore, people must be relocated to a safer place. The results indicate that the concentration threshold can be met beyond the distance of 1 km. Research limitations/implications Due to the economic importance of Skikda refinery and the absence of data related to the accidents in the refineries of Algiers, Arzew and Hassi Messaoud, this study is limited to the statistical analysis of accidents related to Skikda refinery. Practical implications This approach makes the risk assessment more practical and effective for the appropriate utilization of safety barriers and for the whole decision-making process. Originality/value This work presents a review paper of accidents that occurred in the oil-refining sector in Algeria, whose objective is learning lessons from past accidents history, by identifying their immediate causes and effects on personnel, equipment and environment in order to propose prevention measures. The novelty of this work is highlighted by the fact that this statistical analysis of oil and gas refining accident is realized for the first time in Algeria. This is due to the difficulty of obtaining data on accidents in the Algerian refining sector; for this reason, the authors have limited the study to the Skikda refinery.