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Scale-up in Turbula (R) mixers based on the principle of similarities
No full textInternational audienceMany processes from a wide range of industries use powders as raw materials. In most of them, mixing of dry particles is a critical step. However, the complexity of granular materials leads to difficulties in predicting behavior of powders inside a blender. Cost and amount of raw materials needed to achieve these studies imply that such work is often performed at the laboratory scale. The main challenge then lies in the extrapolation of results from lab to pilot or industrial scale with minimum testing in order to optimize costs. Defining reliable scale-up laws for powder mixers remains one of the main industrial issues. The work presented here concerns the scaling-up of Turbula (R) mixers that are commonly used both in industry and research. Mixtures obtained in different mixer sizes have been compared on the basis of kinematic and dynamic similarities and discussed according to the different flow regimes involved. The dynamic similarities appear to lead to mixture qualities at different scales closer to each other than those obtained on the basis of kinematic similarities probably because of similar flow regimes. However, some other parameters must be taken into consideration, such as the free surface of powder related to the filling ratio
Hydroxyapatite as a new support material for cobalt-based catalysts in Fischer-Tropsch synthesis
No full textInternational audienceHydroxyapatite [HAP, (Ca10(PO4)6(OH)2)] is an emerging catalytic support possessing exciting features such as high thermal and mechanical strength, chemically stable with low water solubility along with tunable porosity and acid-basic character. Despite of these interesting characteristics, it has not yet been investigated in Fischer-Tropsch (FT) synthesis. Herein, for the first time, HAP-supported cobalt catalysts (Co/HAP) prepared by conventional incipient wetness impregnation method were examined in the FT synthesis process. The catalytic performance of these catalysts was compared with alumina-supported cobalt catalysts (Co/Alumina). HAP support was found to exhibit considerably less acid-site density, consequently, reducing detrimental interactions of the support with cobalt precursors leading to hardly reducible Co species that are generally observed with its alumina counterpart. Co/HAP catalysts exhibit relatively larger Co particle sizes (~9 nm versus ~6 nm, as observed from TEM analysis) and better Co reducibility when compared to its counterparts on alumina. FT synthesis at 20 bar, 220 °C and H2/CO = 2.1 showed that the CO conversion was higher on the catalysts (10 wt% Co loading) using HAP as a support material when compared to alumina. Under different testing conditions (220 or 230 °C) using the Co/HAP catalyst, the C5+ selectivity was in the range of 82–88%, whereas the methane selectivity was about ~10%
Highly-efficient hydroxyapatite-supported nickel catalysts for dry reforming of methane
No full textInternational audienceNi-based catalysts were prepared using two hydroxyapatites (Ca-HA1, SBET = 7 m2/g and Ca-HA2, SBET = 60 m2/g) with different physico-chemical properties. The objective of the study was to evaluate the performance of these two materials as promising supports for dry reforming reaction (DRM) as well as to investigate the influence of different process parameters, such as temperature, pressure, time and catalyst pretreatment on the performance of these two catalysts. Thermodynamic calculations were performed to determine the conditions that would limit solid carbon deposit and favor the reactants conversion. Then, an experimental parametric study was carried out to investigate the impact of the temperature, pressure, catalyst pretreatment and support thermal treatment on the catalysts performance. The results showed that the catalyst pretreatment allowed the reduction of the nickel particles in a higher extent, which resulted in better catalytic performance when compared to the catalysts without pretreatment. High temperatures around 700 °C and low pressures around 1.6 bar were required to attain high CH4 and CO2 conversions around 70–80% as well as high H2 and CO selectivity around 90% for 90 h of time on stream. In all cases, Ni/Ca-HA2 catalyst presented better catalytic performance than Ni/Ca-HA1 due to the presence of smaller nickel particles (10–20 nm), stronger basicity, higher density of basic sites (0.23 mmol g−1) as well as higher specific surface area (SBET = 60 m2/g) of the Ca-HA2 support. Ni/Ca-HA2 catalyst was highly active (initial methane conversion: 75%) and relatively stable during 90 h of TOS and its catalytic behavior was comparable with the performance of Ni-based catalysts prepared with conventional supports reported in the literature
Cascading effects of risk dedicated to collaborative networked organizations
No full textOver the past few years, the rapid development of information and communications technology has continued to expand the range and forms of information creation and use by humankind. The increasing mobility and flexibility of enterprises have led to the creation of collaborative networks. A collaborative network is a linked system composed of a number of business entities with different geographical locations, operating environments, and corporate cultures. The partners collaborate to better achieve common or compatible objectives and gain differentiated market competition by sharing and complementing their core competencies and resources. However, with the increasing complexity of collaborative environments and the iterative evolution of interaction, partners have to confront the systemic risks caused by their strong dependencies while sharing their benefits. The characteristic of systemic risks is that the occurrence of the risk may trigger cascading effects, causing the risk to spread and propagate continuously in time and space, which may lead to serious loss to the whole collaborative network.Accordingly, accurate and effective management of risk cascading effects is critical to collaborative networked organizations. The identification of potential risk elements and the analysis of hidden risk chain are the key to supporting risk management decision- making. While how to identify and analyze risks depends on how to recognize and understand risks to a great extent. Risk is a complex concept, including causality. The basis of obtaining crucial risk information is to describe and characterize risk in multiple dimensions, then to explore risk causation and propagation mechanism. Nevertheless, existing research in the field of risk has fallen short on the characterization and conceptualization of cascading effect, and the approach to identify the multidimensional risk elements and to analyze the potential risk chains. As a result, the dissertation focuses on the subject of cascading effects of risk dedicated to collaborative networked organizations considering the above research gaps. The research contents of the dissertation are as follows:i. A knowledge representation model of risk causal chain is constructed based on the metamodel of Danger/Risk/Consequence chain. The concept of five core elements of risk causal chain model is defined and the conceptual distinction rules between the elements are summarized based on literature review. Besides, the risk causal process is analyzed according to the essential concepts of those risk-related elements. After that, the riskcausation mechanism is revealed by defining the causal relationships among the five core elements. From the perspective of dynamic collaborative environments, three attributes of the model elements are defined, and the causal connection patterns of model elements with different attributes are analyzed. Furthermore, the above risk causal chain modeling process is summarized as formalized rules in order to increase the normality of risk conceptualization.ii. For the sake of the characteristics understanding of cascading effects, the logical relations between systemic risk, risk propagation and cascading effects are analyzed. Besides, the cascading effect model is constructed based on the risk causal chain model, and three categories of cascading relationships are defined to describe the risk propagation mechanism. In addition, the rules of model construction are formalized according to the modeling process of cascading effect. Moreover, the matrix of propagation patterns of cascading effects considering different interrelationships is summarized to represent the occurrence possibility of cascading effects between different types of risk causal chain.iii. A methodology for the identification and analysis of supply chain cascading effects is proposed, which aims to identify risk-related elements and analyze hidden risk chains. The methodology consists of three main steps and objectives: supply chain risk data analysis and processing, risk identification and risk chain analysis, and collaborative risk prevention strategies. In addition, a supply chain risk knowledge base is constructed based on a comprehensive literature review, which is used to provide a formalized and systematic reference for those steps. Meanwhile, the implementation of them could provide feedback on the risk knowledge base and contribute to its update.iv. The dissertation conducts a case study on the collaborative contexts of construction material supply chain, which aims to verify the rationality of the constructed risk knowledge model as well as the proposed methodology. Firstly, the main business issues of collaborative contexts are analyzed through comprehending the basic characteristics of construction material supply chain. Secondly, those business issues are selected for further risk identification and analysis. Thirdly, the proposed methodology is adopted to identify and analyze risk causal chains as well as risk propagation chains. Finally, according to the results, the case study further discusses the corresponding risk response strategies.The main driving source of risk propagation is the systematic and interconnection nature of risks in complex networks. Regarding collaborative networks, partners are not only the subjects in risk triggering and propagation, but also the receptors exposed to the evolution of risks. Hence, the risk perception, understanding and response patterns of collaborative network partners would directly influence the evolutionary trajectory of risks, the way risk is identified and analyzed, thus the effectiveness of risk management.This dissertation provides an insight into cascading effects of risk to contribute to the understanding and formal description of complex risk concepts and cascading effects. From a risk network perspective, the research work provides decision support information for accurate potential risk identification and detection in complex collaborative networks. From an organization network perspective, it leads partners to recognize the importance of joint participation and the integration of crucial risk information in risk management of collaborative network. Moreover, it also offers a theoretical guideline for collaborative risk prevention and diversified response strategy-making among partners.Non disponibl
Etude théorique et expérimentale d’un composant de stockage thermocline avec matériau à changement de phase : intégration à une centrale électro-solaire à concentration
No full textHeat from concentrated solar plants (CSP) can be efficiently stored at low cost in order to increase the daily operating time of energy production, which represents an advantage on photovoltaic systems. The most common solution for this consists in adding two storage tanks, one for the hot fluid after the concentrators and the other for the cold fluid before them. In order to reduce the operational and capital cost of the installations, research on the thermocline solutions is ongoing: sensible heat is stored in a single tank containing a porous mineral bed, this tank being alternatively charged during daytime and discharged at night with the heat transfer fluid. An issue with this technique is that a temperature gradient exists in such storage systems, which limits the efficiency of the thermocline as a hot source for the thermodynamic cycle combined to the CSP. We are working on the integration of phasechange materials(PCM) in a CSP coupled to a micro solar power plant with 150 kWth capacity and 15 kW ORC turbine. The objective is to design a system offering a more stable outlet temperature than the actual thermocline based on sensible heat storage. The following issues will be addressed during this PhD work: Identify interesting PCM in regard of the potential operating conditions (about 300°C), Measure the thermo-physical properties of the selected materials, Design and develop an encapsulation solution, Install the necessary monitoring probes, Integrate encapsulated PCM into the existing thermocline (working with sensible heat storage) and perform tests with complete system (about 250 kWth storage capacity), Model the whole plant, focusing on heat transfer phenomena around and inside the encapsulated PCM, and in the storage tank, Develop a control system adapted to the management of the thermocline with PCM, Assess the potential of microCSP plants with mixed sensible material-PCM as storage solution; in particular the size effect will be studied.La chaleur produite dans les centrales solaires à concentration (CSC) peut être stockée à faible coût dans le but d’étendre la durée de production d’électricité quotidienne, ce qui représente un avantage sur les systèmes photovoltaïques. La technique le plus souvent employée repose sur deux réservoirs de fluide caloporteur, un chaud et un froid. Des travaux sur le stockage « thermocline » sont actuellement menés en vue de réduire les coûts d’installation du stockage : la chaleur sensible est stockée dans un lit poreux de matériaux inertes, la charge et la décharge se faisant par deux entrées opposées dans le réservoir. Cette technique est limitée par le fait que le gradient de températures (la thermocline) est de plus en plus large au sein du lit poreux au fur et à mesure de son utilisation, donc la température du fluide réchauffé n’est pas constante et le groupe de production perd en puissance. Les travaux porteront sur l’intégration de matériaux à changement de phase (MCP) dans une CSC de 150 kWth. L’objectif est de concevoir un système de stockage à chaleur latente permettant de garantir une meilleure stabilité des températures du fluide caloporteur que le système de thermocline à chaleur sensible. En particulier, les sujets suivants seront abordés : identification des MCP d’intérêt pour l’installation étudiée et caractérisation de leurs propriétés thermo-physiques, mise au point d’une solution d’encapsulation des MCP implémentation dans l’installation existante et essais, modélisation de l’ensemble de l’installation, incluant les phénomènes de transfert externes et internes des MCP encapsulés, établissement d’un système de contrôle commande adapté au stockage mixte MCP/chaleur sensible
Analyse du comportement rhéologique des poudres à partir des propriétés des grains, application à l'étude d'un procédé de broyage/mélange pour la préparation du combustible nucléaire MOX
No full textUp to now, the influence of the physico-chemical properties of the elementary particles on the flowability of bulk powders is still unclear. However, understanding the flow behavior of powders is of upmost importance for optimizing and operating process steps such as transport, storage or various unit process operations involving powders. In particular, the MiMas (Micronized Masterblend) process, implemented in MELOX plant for the preparation of MOX nuclear fuel, handles granular materials, mainly through mixing and grinding steps. In this study, various ceramic powders, essentially alumina, zirconia and yttria powders, have been finely characterized in terms of particle properties and rheological behavior with a powder shear tester. A model, involving the dimensionless granular Bond number to predict the macroscopic flow behavior of a polydispersed powder from its elementary particle properties has been extensively studied. In particular, this model was shown to predict successfully the flowability of binary and ternary mixtures as well as grinded powders according to the particles’ properties and as a function of the operating conditions, such as the composition of the blends or the grinding time. The characterization of grinded and co-grinded powders obtained in a ball mill under various conditions also allowed specifying the influence of various operating parameters, such as the grinding time, the rotating speed or the filling ratio of the vessel. These results were particularly useful for identifying the dimensionless parameters to take into account for the scale up of the grinding equipment. Finally, a methodology for quantifying the homogeneity of powder mixtures, shaped in pellets, at various scales has been developed in order to compare several mixing and co-grinding processes.A ce jour, l’influence des propriétés physico-chimiques des grains élémentaires sur l’écoulement global des poudres n’est pas clairement établie. Pourtant, la connaissance des propriétés d’écoulement des poudres est capitale pour l’optimisation et le fonctionnement des étapes de transport, de stockage, ou encore pour des opérations unitaires de procédés mettant en jeu des poudres. En particulier, le procédé MiMas (Micronized Masterblend), mis en œuvre à l’usine MELOX pour la préparation du combustible nucléaire MOX, repose en grande partie sur la manutention de milieux granulaires, principalement à travers des étapes de mélange et de broyage. Dans cette étude, différentes poudres de céramique, essentiellement d’alumine, de zircone et d’oxyde d’yttrium, ont été caractérisées finement en termes de propriétés des grains et de comportement rhéologique à partir de tests de cisaillements. Un modèle, reposant sur le nombre adimensionnel de Bond granulaire et permettant de prédire la coulabilité macroscopique de poudres polydisperses à partir des propriétés des grains qui la constituent a été développé et validé. Celui-ci a notamment permis de prédire efficacement la coulabilité de mélanges binaires ou ternaires et de poudres broyées en fonction des propriétés des grains, de la composition des mélanges et du temps de broyage. La caractérisation des poudres broyées ou co-broyées dans un broyeur à boulets dans différentes conditions a également permis de préciser l’influence de différents paramètres opératoires tels que le temps de broyage, la vitesse de rotation ou le taux de remplissage de la jarre. Ces résultats ont notamment permis d’identifier les grandeurs adimensionnelles à prendre en compte en priorité pour un changement d’échelle du broyeur. Enfin, une méthodologie permettant de quantifier l’homogénéité de mélanges de poudres, mis sous la forme de pastilles, à différentes échelles a été mise en place dans le but de pouvoir comparer différents procédés de mélange et de co-broyage
Development of a Thermal Energy Storage Pressed Plate Ceramic Based on Municipal Waste Incinerator Bottom Ash and Waste Clay
No full textInternational audiencePressed plates ceramics made of gross-milled bottom ashes and waste clay, were made using technologies available in the building bricks and tiles industry, to ease production upscaling at low-cost. These sintered ceramics are intended for use as a high-temperature thermal energy storage material. They represent an alternative to the waste-based petrurgic ceramics previously developed for this application. Post-treated incinerator bottom ashes from a commercial incinerator were collected, characterized and processed to form ceramic materials, using clay as a binder. Ashes were milled, dried, and mixed with various amounts of an illitic clay (produced as washing mud by a quartz quarry in proportions from 20 to 70% dry weight) prior to uniaxial pressing (12 × 5 × 1 cm slabs) and firing at various temperatures, ranging from 1050 to 1125 °C. The sintered samples have been characterized in terms of volumic mass, mechanical strength, thermal capacity and thermal conductivity. Their mineral structure has also been studied. The resulting sintered ceramics exhibit relatively high mechanical resistance and low thermal conductivity, along with moderate volumic mass. These properties allow envisioning the use as filler material for thermocline thermal storage systems (structured beds), and could be interesting for further work regarding applications in the construction field (bricks, tiles, pavements…)
Towards a Framework for Federated Interoperability to Implement an Automated Model Transformation
No full textPart 4: Data and Knowledge ServicesInternational audienceIn order to adapt to changes in industrial world (customers and markets) and to competition, to create economic or strategic partnerships with external players or simply to integrate a connector to exchange information between the various services and software of a company, it is essential to have the necessary software tools (by development or deployment) that guarantee effective communication between the various parties, which are often heterogeneous and not known in advance, and overcome certain difficulties such as the multiplicity of information sources and the quality of the data.In such a context, the exchange or migration of data is a critical step. In order to facilitate the exchange, our approach aims at implementing federated interoperability with automated model transformation, supported by an interoperability evaluation, in order to ensure data retention despite the unforeseen uses (for example, some fields divert or mislabel) and to ensure their consistency during the transformation
Méthodologie et outil de diagnostic 4.0 : définir sa stratégie de transition 4.0 pour le management de la chaîne logistique
No full textInternational audienceClients and supply chain managers express performance requirements to companies participating in their supply chain. To ensure an overall improvement in supply chain performance, the transition to 4.0 must encompass all of the involved stakeholders. With a view to facilitating the determination of the transformations required of companies, this article sets out to identify a strategy for optimising the overall supply chain in a manner consistent with each stakeholder’s resources. Based on deductive research, we propose the following: (1) a methodology for defining a relevant strategy for 4.0 transition of a supply chain; (2) a qualitative model for assessing the maturity of companies and their entire supply chain, in various areas characterising the 4.0 transformation; and (3) a decision-making tool, taking into consideration each stakeholder’s deviation from clients’ requirements, with a view to identifying and prioritising the development strategy to be followed for a transition to a 4.0 supply chain.Les donneurs d’ordre expriment des exigences de performance envers les entreprises participantes à leur chaîne logistique. Pour obtenir de meilleures performances au niveau global, la transition vers le 4.0 doit être faite avec l’ensemble de parties prenantes. Pour cadrer cette transformation l’article vise à définir une stratégie adaptée aux moyens de chaque maillon afin d’optimiser globalement la chaîne. Les contributions, basées sur une recherche déductive, sont : (1) une méthodologie de définition d’une stratégie pertinente vers une transformation 4.0 d’une chaîne logistique ; (2) un modèle d’évaluation qualitative du niveau de maturité des entreprises et de l’ensemble de leur chaîne logistique, sur les différents axes caractérisant la transformation 4.0 ; (3) sur la base de l’écart constaté dans chaque maillon par rapport aux exigences des donneurs d’ordre, nous proposons un outil d’aide à la décision permettant de déterminer et prioriser la stratégie de développement à adopter pour une transformation vers la chaîne logistique 4.0
Assessment of Ceramic Water Filters for the Removal of Bacterial, Chemical, and Viral Contaminants
No full textInternational audienceIn this study, a comprehensive assessment of doped ceramic water filters (doping with hydroxyapatite and alumina) was conducted for potential application in household water treatment. The efficiency/reliability was assessed via statistical data analysis and normal distributions. It was found that the doped ceramic water filters had high porosity (63.25%±0.31% by volume) and a substantial flow rate (14.76±1.43L·h−1). The removal of bacterial contaminants [i.e., log reduction value (LRV)] was also found to be associated with the percentage of porosity. Hence, the doped filters were both efficient and reliable in removing bacterial contaminants (LRV of 4.69±0.19). The removal of chemical/viral contaminants was related to the doping with hydroxyapatite and alumina. Due to kinetics, the removal of viral contaminants also depended on the flow rate of the doped ceramic water filters. This resulted in high efficiency in the removal of viral contaminants (LRV of 3.47±0.35) and high reliability in the removal of chemical contaminants (LRV of 2.26±0.07). The current results suggest that the doped filters are suitable materials for application in household water treatment