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Thermodynamic Evaluation of the Intermediate Liquid Compounds (ILC) from Biomass Fast Pyrolysis
No full textInternational audienceBiomass fast pyrolysis process is a technology that converts renewable solids into a dense liquid. This study aims to apprehend the thermodynamic behavior of the Intermediate Liquid Compounds (ILCs) observed during the biomass fast pyrolysis. The system studied was a closed system (20 mL) with air and a mixture solution of five components (Acetic acid (AA), hydroxyacetone (HX), phenol; furfural (FF), and methanol) at 90°C and under atmospheric pressure. The flash calculation was conducted at a given temperature and pressure. The vapor-liquid equilibrium compositions were determined by combining the equation of state and activity coefficient models, the Soave-Redlich-Kwong (SRK) equation of state coupled with Modified Huron-Vidal (MHV2) mixing rules incorporating the UNIversal Functionnal Activity Coefficient (UNIFAC) model. Theoretical calculations of vapor-liquid equilibrium compositions were experimentally validated by using a Head-Space GC-MS system. A quantitative agreement between simulated and measured concentrations in the liquid phase was achieved with this combined state-predictive model of the SRK-MHV2-UNIFAC model; thus, confirming that it accounts well for the nonidealities
Production de biobutanol à partir de lignocellulose : un nouveau procédé thermochimique
No full textIn the last years, the energy demand has increased and a large pourcentage of this energy is obtained from fossil fuels, but the use of these fuels has generated CO2 emissions and environmental pollution. For this reason, this research was focused on the use of alternative energies from lignocellulosic biomass to produce renewal fuels decreasing CO2 gas emissions. Canada is a country with high quantities of lignocellulosic biomass which can represent a cheap source for the high value added molecules and fuels production. The first part of the study focuses on the kinetic study of the production of methyl levulinate and levulinic acid from cellulose with a homogeneous catalyst (H2SO4). The second part study the conversion of cellulose to levulinates (platform molecule) using a homogeneous catalyst and a heterogeneous catalyst (Al2(SO4)3). The third part is devoted to study the hydrolysis of methyl levulinate to levulinic acid using copper-based catalysts. Analytical techniques such as SEM, XRD, TPX were used to study the supported catalysts and understand their effect on the reaction. The fourth part of the project relates to the study of the production of 2-butanol from lignocellulosic biomass through the production of methyl levulinate and levulinic acid which are platform molecules and potentially substitutes for biodiesel. Thereafter, the levulinic acid is decarboxylated to 2-butanone and the latter is reduced to 2-butanol using bifunctional catalysts (such as Ru/C and Pt/C) under mild conditions. All of this work contributes to understanding the reactions of the new butanol production process.La demande d'énergie au cours des dernières années a augmenté et un grand pourcentage de l'énergie est dérivée des combustibles fossiles, mais l'utilisation de ces carburants a généré des émissions de CO2 et de la pollution environnementale. Pour ce problème, on a mené des recherches sur l'utilisation des énergies alternatives à partir de biomasse lignocellulosique pour produire des carburants qui réduisent les émissions de CO2. Le Canada est un pays avec une abondance de résidus lignocellulosiques qui sont une source pour la production de différents produits chimiques. La première partie de l’étude se concentre sur l’étude cinétique de la production du lévulinate de méthyle et de l’acide lévulinique à partir de la cellulose avec un catalyseur homogène (H2SO4). La deuxième partie porte sur la conversion de la cellulose en lévulinates (molécule plateforme) en utilisant un catalyseur homogène (H2SO4) et un catalyseur solide (Al2(SO4)3). La troisième partie se consacre sur l’étude de l’hydrolyse du lévulinate de méthyle en acide lévulinique en utilisant des catalyseurs à base de cuivre. Des techniques d’analyse tels que le SEM, XRD, TPX ont été utilisés pour étudier les catalyseurs supportés et comprendre leur effet sur la réaction. La quatrième partie du projet porte sur l’étude des résultats obtenus des différentes réactions réalisées pour la production du 2-butanol à partir de la biomasse lignocellulosique en passant par la production du lévulinate de méthyle et de l’acide lévulinique qui sont des molécules plateforme et potentiellement substitutes au biodiesel. Par la suite, l’acide lévulinique est décarboxylé en 2-butanone et le dernier est réduit en 2-butanol en utilisant des catalyseurs bifonctionnels (tels que le Ru / C et le Pt / C) en conditions douces. L’ensemble de ces travaux contribuent à la compréhension des réactions du nouveau procédé de production du butanol
Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments
No full textInternational audienceMetal Additive Manufacturing and Laser Powder Bed Fusion (LPBF), in particular, have come forth in recent years as an outstanding innovative manufacturing approach. The LPBF process is notably characterized by very high solidification and cooling rates, as well as repeated abrupt heating and cooling cycles, which generate the build-up of anisotropic microstructure and residual stresses. Post-processing stress-relieving heat treatments at elevated temperatures are often required in order to release some of these stresses. The effects of 1 h–hold heat treatments at different specific temperatures (solutionizing, annealing, stress-relieve and low-temperature stress-relieve) on residual stress levels together with microstructure characterization were therefore investigated for the popular Alloy 625 produced by LPBF. The build-up of residual stress is accommodated by the formation of dislocations that produce local crystallographic misorientation within grains. Electron backscattered diffraction (EBSD) was used to investigate local misorientation by means of orientation imaging, thereby assessing misorientation or strain levels, in turn representing residual stress levels within the material. The heavily constrained as-built material was found to experience full recrystallization of equiaxed grains after solutionizing at 1150 °C, accompanied by significant drop of residual stress levels due to this grains reconfiguration. Heat treatments at lower temperatures however, even as high as the annealing temperature of 980 °C, were found to be insufficient to promote recrystallization though effective to some extent to release residual stress through apparently dislocations recovery. Average misorientation data obtained by EBSD were found valuable to evaluate qualitatively residual stress levels. The effects of the different heat treatments are discussed and suggest that the peculiar microstructure of alloys produced by LPBF can possibly be transformed to suit specific application
Investigation of a granular Bond number based rheological model for polydispersed particulate systems
No full textInternational audienceGranular materials are used in many industrial processes among various fields, such as pharmaceutical, food, metallurgy or nuclear fuel production. However, compared to other commonly used media, such as liquids, powders are known to behave unpredictably, leading to uncontrolled process operations. Since the flow behavior of the powders originates from interparticle forces, we suggest a model, linking the macroscopic flowability of powder beds, and the properties of the microscopic particles constituting the powder. A population dependent granular Bond number (Capece et al., 2016), that takes into account the particles properties such as the particles’ true density, surface energy, rugosity and the whole particle size distribution, is used. This non-dimensional number was found to correlate well with the flowability of polydispersed powder bed, which can be measured by shear testing with a Freeman FT4® powder rheometer. The results found in previous studies (Bernard-Granger et al., 2019; Capece et al., 2016) are extended and discussed using five different oxide powders exhibiting various flow behaviors. In particular, a short sensitivity analysis of the model is carried out. The results show that the fraction of fine particles within a polydispersed powder is a critical parameter for the flowability of the powder bed. Finally, the Rumpf’s theory is used to suggest a physical meaning for the model parameters
Monte Carlo et sensibilité géométrique, modèle de transport de sensibilité
No full textNational audienceWe address the question of evaluating shape derivatives of objective functions defined forthe study of energy processes involving semi-transparent media. Facing the limits of the standardapproach to estimate geometric sensitivities by the Monte-Carlo method a new method is presented.A new sensitivity algorithm is detailed in order to extend its implementation, from two examples, inconfigurations with complex geometries with multiple diffusion and a semi-transparent medium.Nous cherchons à estimer les dérivées de formes de fonctions objectif définies pour l’étude de procédés énergétiques. Notre travail s’inscrit dans un contexte où les transferts radiatifs sont une composante majeure des modèles de transferts thermiques. Pour gérer la complexité géométrique de ces configurations d’ingénierie les modèles sont résolus en utilisant la méthode de Monte Carlo. Nous rappelons brièvement les facultés de la méthode de Monte Carlo à résoudre les modèles physiques, une fois exprimés sous leur forme intégrale, ainsi que son aptitude à estimer une fonction objectif et ses dérivées à partir d’un unique algorithme. Effectivement la formulation intégrale de la fonction objectif permet une réécriture intégrale de sa dérivée, qui lui est identique, seuls les poids de Monte Carlo des deux grandeurs sont différents. L’avantage de cette méthode est que l’estimation simultanée de ces grandeurs n’a pas d’influence sur le temps de calcul initialement dû à la seule estimation de la fonction objectif.Dans ce contexte les dérivées de formes ont un statut particulier car les paramètres géométriques interviennent dans le domaine d’intégration de la fonction objectif. Il en découle que dans le cas particulier de perturbations géométriques, afin de garder l’avantage de l’estimation simultanée de la fonction et de ses dérivées, des manipulations mathématiques et de mise en œuvre algorithmiques sont nécessaires. Certaines de ces manipulations, notamment de mise en œuvre, rendent difficile l’application de la méthode en géométrie complexe.Devant ces difficultés nous proposons une alternative pour l’estimation des dérivés de formes qui sont cette fois introduites dès l’écriture du modèle. Nous prenons l’exemple de grandeurs radiatives faisant intervenir la luminance, ce qui reporte la question à déterminer la dérivée de forme de la luminance, c’est à dire sa sensibilité à un paramètre géométrique. A partir de l’équation de transfert radiatif (ETR) nous construisons un modèle sur la sensibilité dans lequel le paramètre géométrique n’intervient qu’aux conditions aux limites.Nous montrons que la sensibilité géométrique obéit strictement aux mêmes lois de transport que la luminance,ce qui implique que nous pouvons utiliser toute notre pratique de l’ETR pour aborder l’équation de transport de la sensibilité, la seule question reste à l’établissement des conditions aux limites. Dans ce travail il est établi que les conditions aux limites en sensibilité rendent compte des contributions du milieu semi-transparent et des conditions aux limites radiative lors d’une perturbation infinitésimale de la frontière. Il en résulte un couplage à la limite entre le modèle de transport de sensibilité et l’ETR. Nous mettons également en évidence l’existence de sources de sensibilité locales générées par les discontinuités des conditions aux limites radiatives.Les conséquences de cette proposition sont de plusieurs types : Lecture et interprétation intuitive de l’impact d’une perturbation de la géométrie sur l’évaluation d’une grandeur objectif radiative. Résolution algorithmique propre à l’estimation de la sensibilité due au couplage de la condition à la limite avec l’ETR et aux discontinuités. Ouverture du champs des configurations abordables, pour l’estimation des dérivées de formes, aux configurations à géométrie complexe avec des exemples, donnés dans ce travail, qui illustrent ce constat
Virtual Reality to Train for Crisis Management
No full textInternational audienceThe EGCERSIS project aims at using virtual reality to improve the efficiency of the crisis management preparation phase. The idea is to tackle the drawbacks of regular crisis management exercises thanks to fully configurable scenarios taking place in digital twins of real critical sites. Virtual exercises will improve, among other things, the frequency, efficiency, and modularity of crisis management preparation, while reducing its costs. In this article, we demonstrate the idea of the project through a simple use-case taking place in a metro station and involving three crisis responders. By linking virtual exercises to our crisis management platform, we also want to demonstrate the usefulness of decision-support systems during a crisis
A new emergency decision support system: the automatic interpretation and contextualisation of events to model a crisis situation in real-time
No full textInternational audienceThis paper studies, designs and implements a new type of emergency decision support system that aims to improve the decision-making of emergency managers in crisis situations by connecting them to new, multiple data sources. The system combines event-driven and model-driven architectures and is dedicated to crisis cells. After its implementation, the system is evaluated using a realistic crisis scenario, in terms of its user interfaces, its ability to interpret data in real time and its ability to manage the 4Vs of Big Data. The input events correspond to traffic measurements, water levels, water flows, water predictions and flow predictions made available by French official services. The main contributions of this study are: (i) the connection between a complex event processing engine and a graph database containing the model of the crisis situation and (ii) the continuous updating of a common operational picture for the benefit of emergency managers. This study could be used as a framework for future research works on decision support systems facing complex, evolving situations
A new family of reduced models for non-isothermal falling films
No full textInternational audienceNew asymptotic models are formulated to capture the thermal transfer across falling films. These models enable to simulate a wide range of Biot and Peclet number values, without displaying nonphysical behaviors. The models correctly capture the onset of the thermally developed regime at the inlet of the flow. To evaluate the parameter space of acceptability, a comparison has been made with the primitive equation solution for periodic boundary conditions, as well as for an open flow with a periodic forcing at inlet. A good agreement is obtained for moderate to high Peclet numbers
Particulate Matter
No full textInternational audienceParticulate matter (PM), defined as the sum of solid and liquid particles suspended in the air, is often divided into two main groups: the coarse fraction with a size ranging from 2.5 to 10 µm (PM10–PM2.5), and the fine fraction with a size smaller than 2.5 µm (PM2.5). PM can be generated from various sources such as unpaved roads, vehicles, agricultural processes, uncovered soil, mining operations, as well as burning of fuels. Statistical data show that in Europe, 1378 thousand tonnes of PM2.5 are generated in year 2016, accounting for 5% of the total main air pollutants including sulphur oxides (SOx), nitrogen oxides (NOx), ammonia (NH3), and non-methane volatile organic compounds (NMVOCs) [1]. This chapter will focus on the thermochemical process of solid fuels such as biomass and biowaste, because these types of fuels today are increasingly being used for energy purposes and have contributed to PM emission in many regions of the world. The presence of PM is significantly relevant to health problems, smog formations, acid rain issues, and climate changes. Characterization of PM is challenging, because PM is not only made up of a complex group of components (mainly black carbon, organics, sulfate, nitrate, alkalis, trace metals, crustal material and salt), but also comes in a wide range of sizes from nanoparticles (diameter less than 0.05 µm) up to millimeter-sized particles. In addition to this, PM characteristics are also proven to depend on various factors such as fuel type, thermal technology and temperature. Detailed knowledge of PM released during biomass and biowaste thermal conversion is essential for controlling air emissions. Over the last decades, attempts have been made to better understand the mechanisms and pathways of PM formation. Also, techniques are developed for PM sampling, collection and analysis, as well as the understanding of its physical and chemical characteristics. This chapter will thus be structured into four parts dedicated to PM fundamentals, collection techniques, physical and chemical characterizations. Available sampling devices, standards, analytical methods and techniques will be presented. Advantages, disadvantages, and major applications regarding biomass and waste thermal conversion will also be presented
Sludge
No full textInternational audienceWater treatment residuals, sewage sludge and dredged sediments, hereinafter referred to as sludge, share common features, like inherent high moisture content, high organic and mineral pollutant load and above all a pasty consistency. Several recovery opportunities exist. However, sludge composition is closely correlated with human activity and the design of the recovery processes requires knowledge of physical, thermal or biological characteristics of the sludge that will be processed, often even before the specific sludge exists. Therefore, sludge characterization is a key challenge for the process design, control and optimization and further valorization. The present chapter is divided into four parts dedicated to the composition, the material properties, the dynamic processing properties and the environmental assessments, respectively. Standard tests methods for the characterization of solids and water distribution in sludge are introduced first. Then, the fate of organic constituents, inorganic nonmetallic and metallic constituents as well as pathogenic organism. In the second part, standard and state-of-the-art methods for the characterization of chemical, physical and thermal properties of sludge are described. Dynamic tests, required for the selection and design of conventional processes for sludge concentration and conveying, are detailed in the third part. Finally, methods for assessing the environment impacts of sludge and secondary raw materials derived from sludge are addressed