Evolution des méthodes de protection des procédés industriels contre les effets des explosions : le projet DELFINE)

National audienceClassical methods for vent sizing are based on experimental correlations coming from academic test situations, sometime quite different from real industrial conditions. Thus, they do not take into account the variation of turbulence in industrial enclosures, which may alter drastically the explosion violence. The DELFINE installation presently in construction will allow studying dust explosions in real working conditions of a dust collector. Preliminary experiments in an instrumented small size filter are presented, which allow characterizing the turbulence level in every work phase of the system. It appears that the turbulence level is generally lower than in the standard conditions for vent testing, even during reverse jet cleaning. It should offer perspective for optimization of the venting areas for dust collectors. Explosion tests in real conditions on the DELFINE installation will be performed to try to confirm these first observations.Les industries de la chimie, du bois et de l'agroalimentaire concentrent plus de 80% des explosions de poussières recensées en France au cours des 100 dernières années [1]. Pour cette raison il existe aujourd'hui un secteur industriel qui propose des solutions de maîtrise des risques d'explosion de poussière et met sur le marché, qui des technologies de protection, qui des appareils équipés de ces technologies dès la conception. Si des normes relatives à ces stratégies industrielles ont été proposées comme pendant à la Directive ATEX [2], il a été observé qu'elles étaient loin de couvrir la réalité des procédés industriels. Cela est perçu comme un obstacle majeur à l'ingénierie de la sécurité des procédés puisqu'on ne possède pas de " méthodes d'ingénieur " suffisantes. L'objectif du projet DELFINE qui réunit les moyens de FIKE Corp. (producteur de systèmes de protection), de DELTA NEU (producteur de process industriels de filtration) et de l'INERIS (Expert de la phénoménologie de l'explosion) est de promouvoir des méthodes de dimensionnement des systèmes de protection en commençant par la technologie des évents. On présente dans cette communication les résultats obtenus au plan de la modélisation phénoménologique du développement des explosions dans les systèmes industriels (réseaux d'enceintes et de canalisations) et les premiers résultats expérimentaux obtenus à l'échelle réelle au moyen d'une boucle d'essai de dépoussiérage spécialement conçue pour le projet

A kinetic free mathematical model for the prediction of the KStreduction with the particle size increase

Even in recent years, several major industrial accidents have involved dust explosions, clearly showing the necessity of mitigating the hazard related to the presence of flammable dusts. In this respect, the KStis an experimental parameter used to design the deflagration vents aimed to protect industrial devices and silos by internal dust explosions. Even if it is measured using a standard 20 L sphere test, its determination is quite expensive and time consuming. This problem is even more severe when a target dust is processed into a plant, giving rise to different average diameters; in this case, an experimental investigation of all the different particle sizes would be advisable but very expensive. In this context, the main aim of the present paper has been to develop a kinetic-free model able to predict the KStdecrease with the mean particle diameter increase for organic dusts explosions. Particularly, an order of magnitude analysis of the characteristic times of the involved phenomena has showed that, in the KStmeasurements, the rate determining step is usually associated to heat transfer phenomena. This evidence leads to the possibility of exploring a predictive approach for the KStdetermination which does not require any chemical kinetic information, the most difficult to be obtained. Therefore, once the value of KSthas been measured through a standard 20 L test for a given mean particle diameter (the smallest possible), the approach proposed in this work allows for predicting the KStvalues for the same dust at higher average particle sizes. Such an approach has been validated by comparison with several literature data as well as with a new set of experimental results

Prediction of the deflagration index for organic dusts as a function of the mean particle diameter

All the recently occurred accidents involving powdered materials demonstrate that dust explosion is up to now an open problem. To mitigate the effects of this phenomenon on people, environment and equipment, it is important to understand the characteristics of the potentially explosive material which can affect the violence of a dust explosion. The deflagration index is the most relevant recognized parameter able to measure the severity of such a phenomenon. Among all the critical issues affecting the use of this parameter for industrial safety, the particle size distribution of the tested powder plays a relevant role. In this paper, a simple but reliable mathematical model has been proposed to describe the effect of the mean particle diameter on the dust explosibility. Model predictions have been compared with both literature and new experimental data in order to validate the general proposed approach

The effect of food on the intraluminal behavior of abiraterone acetate in man

To relate the reported positive effect of food on the oral bioavailability of abiraterone to the intraluminal behavior of abiraterone acetate, an in vivo experiment was performed, in which duodenal fluids and plasma samples were collected from healthy volunteers after the administration of abiraterone acetate in fasted and postprandial conditions. The plasma concentration-time profiles confirmed the positive food effect. Nevertheless, intraduodenal concentrations of abiraterone acetate and abiraterone did not fully reflect this observation. This apparent discrepancy was explored by performing several in vitro experiments including solubility, dissolution, and transfer studies. Gastrointestinal transfer studies illustrated a positive impact of gastric processing of the abiraterone acetate formulation on the duodenal concentrations in the fasted state, which could not be observed in the postprandial condition. As the influence of gastric dissolution on the intraluminal concentrations in the small intestine declines aborally, it is most likely the superior solubility of abiraterone acetate and abiraterone in intestinal fluids of the fed state that dictates the food effect. Furthermore, N-oxide abiraterone sulfate and abiraterone sulfate appeared in the duodenum at significantly later time points than abiraterone, suggesting biliary excretion of these abiraterone metabolites; this was confirmed by in situ biliary excretion experiments in rats.publisher: Elsevier articletitle: The Effect of Food on the Intraluminal Behavior of Abiraterone Acetate in Man journaltitle: Journal of Pharmaceutical Sciences articlelink: http://dx.doi.org/10.1016/j.xphs.2016.03.008 content_type: article copyright: © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.status: publishe

Rapid conversion of the ester prodrug abiraterone acetate results in intestinal supersaturation and enhanced absorption of abiraterone: In vitro, rat in situ and human in vivo studies

The aim of this study was to evaluate the intestinal disposition of abiraterone acetate, an ester prodrug of the anticancer agent abiraterone. Stability of the prodrug and solubility and dissolution characteristics of both abiraterone and abiraterone acetate were monitored in vitro. Moreover, the in vivo intraluminal concentrations of abiraterone and abiraterone acetate upon intake of one tablet of 250mg abiraterone acetate were assessed in healthy volunteers. The intestinal absorption resulting from the intraluminal behavior of the ester prodrug was determined using the rat in situ intestinal perfusion technique with mesenteric blood sampling. Simulated and aspirated human intestinal fluids of the fasted state were used as solvent systems. Upon incubation of abiraterone acetate in human intestinal fluids in vitro, rapid hydrolysis of the prodrug was observed, generating abiraterone concentrations largely exceeding the apparent solubility of abiraterone, suggesting the existence of intestinal supersaturation. These findings were confirmed in vivo, by intraluminal sampling of duodenal fluids upon oral intake of an abiraterone acetate tablet by healthy volunteers. Rat in situ intestinal perfusion experiments performed with suspensions of abiraterone and abiraterone acetate in human intestinal fluids of the fasted state revealed significantly higher flux values upon perfusion with the prodrug than with abiraterone. Moreover, rat in situ intestinal perfusion with abiraterone acetate suspensions in simulated fluids of the fasted state in presence or absence of esterases demonstrated that increased hydrolytic activity of the perfusion medium was beneficial to the intestinal absorption of abiraterone. In conclusion, the rapid hydrolysis of abiraterone acetate in the intraluminal environment appears to result in fast and extensive generation of abiraterone supersaturation, creating a strong driving force for abiraterone absorption.publisher: Elsevier articletitle: Rapid conversion of the ester prodrug abiraterone acetate results in intestinal supersaturation and enhanced absorption of abiraterone: In vitro, rat in situ and human in vivo studies journaltitle: European Journal of Pharmaceutics and Biopharmaceutics articlelink: http://dx.doi.org/10.1016/j.ejpb.2015.01.001 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved.status: publishe

Investigation of the intraluminal behavior of abiraterone acetate

status: publishe