Offshore oil and gas platforms are well known for their compact geometry, high degree of congestion, limited ventilation and difficult escape routes. A small mishap under such conditions can quickly escalate into a catastrophe. Among all the accidental process-related events occurring offshore, fire is the most frequently reported. It is, therefore, necessary to study the behavior of fires and quantity the hazards posed by them in order to complete a detailed quantitative risk assessment. While there are many consequence models available to predict fire hazards-varying from point source models to highly complex computational fluid dynamic models—only a few have been validated for the unique conditions found offshore.
In this paper, we have considered fire consequence modeling as a suite of sub-models such as individual fire models, radiation model, overpressure model, smoke and toxicity models and human impact models. This comprehensive suite of models was then revised by making the following modifications: (i) fire models: existing fire models have been reviewed and the ones most suitable for offshore conditions were selected; (ii) overpressure impact model: a model has been developed to quantify the overpressure effects from fires to investigate the possible damage from the hot combustion gases released in highly confined compartments; (iii) radiation model: instead of a point/area model, a multipoint grid-based model has been adopted for better modeling and analysis of radiation heat flux consequences. A comparison of the performance of the revised models with the ones used in a commercial software package for offshore risk assessment was also carried out and is discussed in the paper. 相似文献
The results of the UN test O.1 for oxidizing solids are shown to be incorrect when specimens contain certain inertant additives, illustrated for the case of oxidizers in the ammonium nitrate fertilizer family. Test results for three different AN-based products containing inertants show that two of the three (including calcium ammonium nitrate, CAN, a long-known safer alternative to AN) would be misranked with the O.1 test. An analogy between the heat release rate of substances containing fire retardant (FR) chemicals is established and several ways by which FR behavior can be achieved are demonstrated. It is shown that the O.1 test implicitly adopts only one model of inertant action, and that chemicals which rely on a differing mode of inertant action are liable to be incorrectly treated. It is further shown that the physical basis of the O.1 test—an intimate mixture of finely-comminuted fuel and oxidizer—misrepresents the most common type of accidents involving oxidizers, and that such test results do not correspond to scenarios of a less extreme nature. The new O.3 test improves the analysis method, but does not resolve the problem of excessive commingling of fuel into oxidizer. It is recommended that the intermediate-scale arrangement used by the Bureau of Explosives be adopted for further development and standardization, in preference to the O.1 or O.3 test arrangements. 相似文献
Fire is the most commonly occurring major accident hazard in the chemical and process industries, with industry accident statistics highlighting the liquid pool fire as the most frequent fire event. Modelling of such phenomena feeds heavily into industry risk assessment and consequence analyses. Traditional simple empirical equations cannot account for the full range of factors influencing pool fire behaviour or increasingly complex plant design. The use of Computational Fluid Dynamics (CFD) modelling enables a greater understanding of pool fire behaviour to be gained numerically and provides the capability to deal with complex scenarios.This paper presents an evaluation of the Fire Dynamics Simulator (FDS) for predictive modelling of liquid pool fire burning rates. Specifically, the work examines the ability of the model to predict temporal variations in the burning rate of open atmosphere pool fires. Fires ranging from 0.4 to 4 m in diameter, involving ethanol and a range of liquid hydrocarbons as fuels, are considered and comparisons of predicted fuel mass loss rates are compared to experimental measurements.The results show that the liquid pyrolysis sub-model in FDS gives consistent model performance for fully predictive modelling of liquid pool fire burning rates, particularly during quasi-steady burning. However, the model falls short of predicting the subtleties associated with each phase of the transient burning process, failing to reliably predict fuel mass loss rates during fire growth and extinction. The results suggest a range of model modifications which could lead to improved prediction of the transient fire growth and extinction phases of burning for liquid pool fires, specifically, investigation of: ignition modelling techniques for high boiling temperature liquid fuels; a combustion regime combining both infinite and finite-rate chemistry; a solution method which accounts for two- or three-dimensional heat conduction effects in the liquid-phase; alternative surrogate fuel compositions for multi-component hydrocarbon fuels; and modification of the solution procedure used at the liquid-gas interface during fire extinction. 相似文献
The minimum ignition temperature of dust suspension (MIT) and the hot surface ignition temperature of the dust layer (LIT) are essential safety parameters for the process industry. However, the knowledge of the ignition behavior when solid mixtures of flammable fuels and phosphorous-free inhibitors are considered is still scarce and further experimental and theoretical analyses are requested. In this work, the ignition temperature of phosphorous-free inhibitors (coal fly ash and calcium carbonate) mixed with lycopodium dust have been studied in terms of LIT analysis (hot plate thickness: 5 mm, 12.5 mm and 15 mm), and by the Godbert-Greenwald test for the MIT. Both coal fly ash and calcium carbonate have been tested at different concentrations and particle sizes.Results show that the effects of the inhibitor can be counter-productive when layer ignition temperature is considered even if the minimum ignition temperature of the dust suspension shows a positive effect from the safety point of view. This behavior has been analyzed in the terms of thermal conductivity and diffusivity of the mixture, by using Maxwell's equation for two-phase solid mixtures. Standard empirical correlations for the ignition temperature of solid mixtures have been also tested, showing their weakness in reproducing mixture behavior. 相似文献
Ammonium nitrate is used in vast amounts globally, first and foremost as a component of fertilizers and explosive formulations. This usage necessitates its transportation which, as for most hazardous materials, involves certain risks. For oxidizing materials such as ammonium nitrate, the ultimate consequence of road transportation incidents is usually considered to be fire followed by explosion. Even though the probability in general is low, substantial reduction in its risk is a great gain for public safety. Thus, identifying novel and improving current safety measures for risk reduction, is an important aspect in the field of hazardous materials. Herein, a series of experiments are reported, which demonstrate the fire protection performance of two state-of-the-art intumescent passive fire protection materials on small-scale metal test tubes containing ammonium nitrate. Albeit being initial experiments on laboratory-scale, these results provide a promising starting point for further investigations on the potential of these materials for the fire protection of ammonium nitrate when carried in metal tanks. At its best, a prominent protection of ammonium nitrate from heat exposure was observed, as the temperature was kept well below its boiling point for more than 2.5 h. Successively, it resulted in a complete recovery of the sample material. This was in large contrast to the observed results for the unprotected test tubes, which led to complete decomposition of the sample after 11 min. 相似文献