Sizing safety vents for non-tempered systems (organic peroxides): a new tool at lab scale

National audienceThis paper deals with the development of a new experimental “similarity” vent sizing tool for non tempered chemical system combining the advantages of both DIERS method (laboratory scale) and UN similarity method (less overconservative). This tool is an extension of the VSP2 (Vent Sizing Package II) adiabatic calorimeter. The objective of this new vent sizing tool is twofold. The first is to provide the required A/V ratio necessary to assure a safe relief. The second is to provide measurement of mass vented during blow-down. This paper gives a description of this tool and exposes the first promising results obtained. Its main limits are also given

Une recherche partenariale appuyant l'évolution de la réglementation : Un cas délicat de dimensionnement d'évent pour le stockage de peroxydes organiques

National audienceLes dangers présentés par les peroxydes organiques sont très variés, et dans tous les cas, le risque d'emballement thermique, avec explosion pneumatique du contenant est à considérer. Dans le cas étudié, le danger de déflagration ou d'explosion pneumatique éliminé au niveau du stockage mère par l'emploi d'un emballage plastique de 35 litres peu résistant, réapparaît au cœur même de l'unité de polymérisation utilisant le peroxyde, car le concepteur a prévu un stockage tampon en cuve inox d'environ 1 m3 . La préparation de ditertiobutylperoxyde (DTBP) peut donner lieu à une explosion en phase gazeuse même sous azote, induisant éventuellement une déflagration de la phase liquide. Plus classiquement, on doit tenir compte du scénario d'emballement thermique du stockage menant à l'éclatement de la cuve, suite à un incendie extérieur ou à un auto-échauffement. Nous avons réalisé des essais à l'échelle de 0,8 - 10 et 20 litres, en modifiant des méthodes normalisées ou recommandées internationalement ; une évolution de ces méthodes sera proposée dans le futur. Nous avons pu ainsi étudier le couplage entre 'explosion en phase gazeuse et l'emballement thermique de la phase liquide pour le DTBP, et proposer au vu des résultats des recommandations pour réduire dès la conception de l'installation l'apparition de ce phénomène, tout en limitant la violence de l'emballement thermique s'il apparaît. La présente étude a aussi permis de contribuer à mieux comprendre comment établir le projet d'arrêté pour les cas très différents du stockage et de l'usage des peroxydes, dans le contexte de la révision de la nomenclature et les arrêtés relatifs au stockage et à l'utilisation des peroxydes organiques, au titre des Installations Classées pour la Protection de l'Environnement (ICPE)

Vent sizing: Analysis of the blowdown of a hybrid non tempered system

International audienceThe runaway and blowdown of a non tempered hybrid chemical system (30% cumene hydroperoxide) exposed to an external heat input was investigated using a 0.1 l scale tool. The maximum temperature and the maximum temperature rise rate were showed to be sensitive to the vent size. An Antoine type correlation between the maximum temperatures and pressures was observed. These resulted from the presence of vapour, mainly generated by the reaction products. Increasing the initial filling ratio resulted in an earlier vent opening but did not have a significant influence on the blow-down. Three types of mass venting behaviour were observed, when changing the vent area to volume ratio (A/V): * for large A/V, two-phase venting occurred from the vent opening until the end of the second pressure peak; * for medium A/V, two-phase venting occurred before and after the turnaround. The data seem to indicate that gas only venting occurred at turn-around; * for low A/V, two-phase venting was observed only after the second pressure peak. Two-phase venting after the second pressure peak probably results from the boiling of the hot reaction products at low pressure

Analyse de l'emballement thermique d'un système chimique hybride non tempéré

National audienceCe travail s'intéresse au “blow-down” (emballement thermique en présence d'un évent de sécurité) d'un système chimique non tempéré (30% CHP) soumis à un incendie. Il utilise une maquette à l'échelle 0,1 l. L'analyse des données post décomposition a montré que la vapeur présente est principalement un produit de la réaction. Toutes les expériences de blow-down ont présenté deux pics de pression, quel que soit le rapport A/V, ce qui est typique des systèmes non tempérés. Nous avons cependant constaté que la température maximale (Tmax) et la vitesse maximale de montée en température ( ) sont sensibles à la taille de l'évent. Nous avons de plus observé une corrélation de type Antoine entre Pmax et Tmax, avec Pmax plus faible que la pression d'équilibre. Cela montre que la cinétique de la décomposition de CHP est sensible à la vaporisation de ses propres produits. Pour le blow-down de CHP 30%, nous avons globalement identifié à la fois des caractéristiques communes avec ce qui se passe pour un système purement gazogène, et des différences importantes dues à l'influence de la vapeur formée

Denudation of the Côte d'Ivoire-Ghana transform margin from apatite fission tracks.

Apatite fission track analysis of samples from the shoulder (marginal ridge) of the Côte d'Ivoire-Ghana transform continental margin reveal a cooling of the margin between 85 and 65 Ma for the central and eastern parts of the ridge. All samples were heated in situ during sedimentary burial with a temperature >120 °C, except for two samples located in the eastern part which were heated between 105 and 120 °C. For the first time, age/depth diagram along a transform margin shows a shape involving erosion starting at the bottom of the continental slope, then stepping backwards towards the edge of the slope. This retrogressive erosion can result from the deepening of the lithospheric plate sliding along the transform margin, from thick continental crust to thin continental crust, and finally to oceanic crust. This process could be at the origin of the shoulder uplift by flexural response to the important crustal discharge (>2 km)

Loss of containment: Experimental validation of initially subcooled two phase critical flow models

International audienceA new setup allows us to experiment initially subcooled two-phase critical flows with five different fluids: water, R11, methanol ethyl acetate and butane. We verify that good estimates of the mass flow rate can be derived from the extended HEM for all of the fluids in high subcooling conditions (within ± 20% accuracy). In low subcooling conditions, a satisfactory agreement (± 30% accuracy) with the DEM or HEM predictions is found. This means that the main phenomena involved seem to be correctly taken into account

Investigation of a Specific Magnetic Characterization dedicated to Manufactured Massive Cores

Projet PSPC LowCO2Motion porté par VALEO. Financement BPI France.Magnetic parts are usually composed of a stack of electrical steel laminations to reduce the eddy current losses. However, for cost reasons or for specific applications the magnetic core can be made from massive steel and thus manufactured with adapted processes such as forging. This kind of process may imply anisotropy and severe inhomogeneity of the material properties. Therefore, for accurate design or study of the electromagnetic part, it is necessary to account for the real properties of the material. In that context, most of the standard characterization procedures are not adapted to represent the magnetic flux behavior through a bulk material and applicable for material anisotropy at the same time. The proposed specific characterization procedure aims at considering these both aspects

Characterization of massive magnetic parts with a dedicated device

Magnetic parts are usually composed of a stack of electrical steel laminations to reduce the eddy current losses. However, for cost reasons or for specific applications the magnetic core can be made from massive steel and thus manufactured with adapted processes such as forging. Such process may lead to inhomogeneous and degraded magnetic properties. Therefore, this study proposes a specific device for characterizing magnetic properties of samples which are to be representative of a massive part. The measure is based on the Faraday’s equation to determine the magnetic flux density and the Hall effect to estimate the magnetic field inside the sample. Practically this is realized with classical components such as Hall probes, a secondary winding and an electromagnet device. However their combination is unique to perform magnetic characterization on massive samples, which are less affected by the sampling technique and may have anisotropic properties. The device is dimensioned thanks to FE-Simulation and validated according repeatability, sensitivity and trueness analysis. Eventually the characterization is performed on samples with different material parameters showing the effect of the grain size on the specific losses. The expected effect of the grain flow on magnetic properties is however not proven yet.PSPC Lowco2motio

Procédés de fabrication en matériaux composites de pièces tridimensionnelles et/ou massives

L'invention concerne un procédé pour fabriquer en matériau composite une pièce brute ayant une forme massive et/ou tridimensionnelle, comprenant les étapes de : - bobiner à chaud au moins un toron de fibres renforçantes (24) imprégné de résine thermoplastique en quantité excédentaire, sur des reliefs de bobinage (17-23 ) d'un outillage de bobinage (16), pour constituer une préforme de la pièce fabriquée ; - matricer à chaud la préforme pour lui donner une forme souhaitée tout en évacuant la résine excédentaire ; - refroidir l'ensemble en maintenant sous pression l'outillage de matriçage (31) pour constituer la pièce brute. L'invention s'applique à la fabrication de pièces mécaniques structurelles telles que des pièces structurelles aéronautiques

Density dependence in the spatial behaviour of anchovy and sardine across Mediterranean systems

A spatial indicator—the spreading area index—is used to describe anchovy and sardine spatial distribution in relation to biomass variation and to look for ecosystem differences within the Mediterranean basin. Specifically, the variation in the spreading area index in relation to biomass was examined for different areas of the Mediterranean Sea (i.e. Aegean Sea, western Adriatic Sea, Strait of Sicily, Gulf of Lion, and Spanish Mediterranean waters). In order to capture the spatial variability of the population at different levels of fish density, acoustic survey data for the years of highest, lowest, and intermediate abundance were used. In a subsequent step standardized values of spreading area and biomass were estimated to allow comparisons. Results showed pronounced area differences. A significant relationship was revealed in the case of anchovy for areas with extended continental shelf (i.e. Aegean Sea, Adriatic Sea, and Gulf of Lion), indicating an increase in biomass with an increase in the spreading area. No relationship was found for areas dominated by narrow continental shelf and strong currents (i.e. Spanish Mediterranean waters and the Strait of Sicily). With regard to sardine, an increase in biomass was followed by an increase in the spreading area when estimates from the Aegean Sea, the Adriatic Sea, and the Strait of Sicily were considered together. The relationship was even more Abstracts–Theme Session B 9 pronounced when analysis was limited to the Aegean Sea and the Strait of Sicily. No relationship was found for the Spanish Mediterranean waters and the Gulf of Lion. This clearly implies that spatial indicators should be integrated into ecosystem management, taking into account that they can be area‐ or ecosystem‐dependent