Domino effects : thermal impact of jet fires on industrial pipes
Résumé
Due to accidental thermal attacks, industrial plants can be damaged or more seriously become themselves the centre of major accidents (domino effects). At the origin of these attacks, it is advisable to mention the "classical" fires such as pool fires, jet fires, but also more exceptional phenomena which generate fire balls with an intense radiation as BLEVE or Boil-Over. Therefore, as part of hazard surveys and more particularly survey of domino effects, some questions are asked about, for example: - the relevance to consider the explosion of such or such tank as a result of the contribution of heat since a close fire considered besides, - or again the quantitative earnings expected by the implementation of materials of heat insulation or the implementation of means of cooling. Now it concerns typical structures as pipes or tanks, there are not or few tools which are enough fine to answer the previous asked questions and at the same time there is not enough quick implementation to be compatible with the deadline constraints of usual studies. Thus a research programme focuses on the thermal impact of different fires on industrial pipes and tanks. Its objective is to develop, to validate and to produce one or several tools of calculation satisfying needs mentioned above in order to approach in a most realistic possible way the thermal impact of fires on equipment such as the industrial pipes and tanks. This paper presents an experimental campaign aiming to the analysis of the heat transfers being exerted on a pipe submitted at a fire jet. Thus, an experimental apparatus was set up making it possible to determine on the one hand, precisely the characteristics of jet fire and on the other hand, the thermal response of the pipe crossed by water. To characterise jet fire, measurements of gas temperatures, gas velocities and heat fluxes are realised for three gases that are the methane, propane and ethylene and for various gas release rates. Additionally, test monitoring has also been done, making use of both infrared camera and conventional video camera. These measurements make it possible to define dimensions of jet fires, its surface emissive power as well as the hot gas velocities for then deducing from them the heat transfers received by the pipe. In the second time, the pipe crossed by water is subjected to these various jet fires and the thermal response of pipe is quantified by monitoring the pipe with thermocouples. The experimental apparatus makes it possible to vary various parameters such as: - the presence or not of an heat insulator like rockwool, - the thermal attack (various gases and heat release rates), - the flow velocity in the pipe going from 0,1 to 1 m/s. This test campaign aims to validate the physical models concerning the thermal response of a structure to a thermal attack and to quantify the influence of the hot soots conduction in the heat transfers by testing jet fires of gas producing soots more or less.
Origine : Fichiers produits par l'(les) auteur(s)
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