Hydrogenated nitrile butadiene rubber (HNBR) which is known for its excellent elastomeric properties and mechanical retention properties after long time exposure to heat, oil and air is produced by the catalytic hydrogenation of nitrile butadiene rubber (NBR). Hydrogenation of NBR is carried out preferably in solution via homogeneous catalysis. As yet, it is being commercially produced in a semi-batch process where gaseous hydrogen continuously flows into a batch of reactant polymer. Several catalysts have been exploited successfully for the hydrogenation of NBR in organic solvents, which include palladium, rhodium, ruthenium, iridium and osmium complexes. Owing to the drawbacks of batch production (such as time taken for charging and discharging the reactants/products, heating and cooling, reactor clean up), and the huge demand for HNBR, a continuous process is proposed where potential time saving is possible in addition to the high turn over of the product. Numerical investigation of the HNBR production in a plug flow reactor and a continuous stirred tank reactor showed that a reactor with plug flow behavior would be economical and efficient. A static mixer (SM) reactor with open-curve blade internal geometry is designed based on the simulation and hydrodynamic results. The SM reactor was designed with 24 mixing elements, 3.81 cm ID and 90 cm length. The reactor has a jacket in which steam is used to heat the polymer solution. The hydrodynamics in the SM reactor (open-flat blade structure) with air-water system showed that plug flow could be achieved even under laminar flow conditions (Reh < 20). For a constant mean residence time, the Peclet number was varying such that it is 4.7 times the number of mixing elements (ne) used in the SM reactor. Empirical correlations were developed for gas hold up (εG) and overall mass transfer coefficient (KLa). The mass transfer experiments showed that high KLa, 4 to 6 times compared to that of the conventional reactors could be achieved in the SM reactor at particular operating conditions. Very important information on the Peclet number, liquid hold were obtained from the hydrodynamic experiments conducted with the actual working fluids (hydrogen, polymer solutions) in the SM reactor. The superficial gas velocity had an adverse effect on both Peclet number and liquid hold up. The viscosity of the polymer solution also had a marginal negative effect on the Peclet number while a positive effect on the liquid hold up. The hydrogenation performance with the homogeneous catalyst OsHCl(CO)(O2)(PCy3)2 was performed in the continuous process with SM reactor. Complete hydrogenation of NBR was possible in a single pass. The effect of mean residence time, catalyst and polymer concentration on the final degree of hydrogenation was studied. The minimum catalyst required to achieve degree of hydrogenation over 97% was empirically found and an empirical correlation was developed for degree of hydrogenation as a function of operating conditions and parameters. Hydrogenation in the SM reactor is modeled by using plug flow with axial dispersion model that is coupled with the concentrations of carbon-carbon double bond, hydrogen and osmium catalyst. The model involves coupled, non-linear partial differential equations with different dimensionless parameters. The proposed model was verified with the experimental results obtained from the hydrogenation and hydrodynamic experiments. The model could satisfactorily predict the degree of hydrogenation obtained from experimental results at various operating conditions. In general, the designed continuous process with SM reactor performed well and was an effective method of manufacturing HNBR on a continuous basis. The designed system is amicable to the industrial operating conditions and promises to be highly efficient and economic process for production of HNBR.

Hydrogenated nitrile butadiene rubber (HNBR) which is known for its excellent elastomeric properties and mechanical retention properties after long time exposure to heat, oil and air is produced by the catalytic hydrogenation of nitrile butadiene rubber (NBR). Hydrogenation of NBR is carried out preferably in solution via homogeneous catalysis. As yet, it is being commercially produced in a semi-batch process where gaseous hydrogen continuously flows into a batch of reactant polymer. Several catalysts have been exploited successfully for the hydrogenation of NBR in organic solvents, which include palladium, rhodium, ruthenium, iridium and osmium complexes. Owing to the drawbacks of batch production (such as time taken for charging and discharging the reactants/products, heating and cooling, reactor clean up), and the huge demand for HNBR, a continuous process is proposed where potential time saving is possible in addition to the high turn over of the product. Numerical investigation of the HNBR production in a plug flow reactor and a continuous stirred tank reactor showed that a reactor with plug flow behavior would be economical and efficient. A static mixer (SM) reactor with open-curve blade internal geometry is designed based on the simulation and hydrodynamic results. The SM reactor was designed with 24 mixing elements, 3.81 cm ID and 90 cm length. The reactor has a jacket in which steam is used to heat the polymer solution. The hydrodynamics in the SM reactor (open-flat blade structure) with air-water system showed that plug flow could be achieved even under laminar flow conditions (Reh < 20). For a constant mean residence time, the Peclet number was varying such that it is 4.7 times the number of mixing elements (ne) used in the SM reactor. Empirical correlations were developed for gas hold up (εG) and overall mass transfer coefficient (KLa). The mass transfer experiments showed that high KLa, 4 to 6 times compared to that of the conventional reactors could be achieved in the SM reactor at particular operating conditions. Very important information on the Peclet number, liquid hold were obtained from the hydrodynamic experiments conducted with the actual working fluids (hydrogen, polymer solutions) in the SM reactor. The superficial gas velocity had an adverse effect on both Peclet number and liquid hold up. The viscosity of the polymer solution also had a marginal negative effect on the Peclet number while a positive effect on the liquid hold up. The hydrogenation performance with the homogeneous catalyst OsHCl(CO)(O2)(PCy3)2 was performed in the continuous process with SM reactor. Complete hydrogenation of NBR was possible in a single pass. The effect of mean residence time, catalyst and polymer concentration on the final degree of hydrogenation was studied. The minimum catalyst required to achieve degree of hydrogenation over 97% was empirically found and an empirical correlation was developed for degree of hydrogenation as a function of operating conditions and parameters. Hydrogenation in the SM reactor is modeled by using plug flow with axial dispersion model that is coupled with the concentrations of carbon-carbon double bond, hydrogen and osmium catalyst. The model involves coupled, non-linear partial differential equations with different dimensionless parameters. The proposed model was verified with the experimental results obtained from the hydrogenation and hydrodynamic experiments. The model could satisfactorily predict the degree of hydrogenation obtained from experimental results at various operating conditions. In general, the designed continuous process with SM reactor performed well and was an effective method of manufacturing HNBR on a continuous basis. The designed system is amicable to the industrial operating conditions and promises to be highly efficient and economic process for production of HNBR.

<p>Cilj ovog rada je ispitivanje uticaja procesnih<br />parametara (transmembranski pritisak, protok i<br />koncentracija suspenzije) na vrednost fluksa<br />permeata, sa i bez prisustva statičkog me&scaron;ača,<br />tokom procesa mikrofiltracije suspenzija<br />p&scaron;eničnog skroba na keramičkim membranama<br />različitih veličina pora (200 nm i 500 nm).<br />Mikrofiltracija je izvođena u uslovima<br />recirkulacije i koncentrisanja napojne suspenzije.<br />Za modelovanje zavisnosti procesa mikrofiltracije<br />suspenzija skroba od procesnih parametara<br />primenjen je postupak odzivne povr&scaron;ine.<br />Ispitivanjem mikrofiltracije suspenzija p&scaron;eničnog<br />skroba na membranama sa različitim srednjim<br />prečnikom pora (200 i 500 nm) uočeno je da sa<br />povećanjem veličine pora vrednost fluksa<br />permeata opada.<br />U posmatranom eksperimentalnom opsegu<br />procesnih parametara postignuto je relativno<br />povećanje stacionarnog fluksa od 25% do 50% u<br />uslovima recirkulacije napojne suspenzije, dok je<br />u uslovima koncentrisanja napojne suspenzije<br />relativno povećanje srednjeg fluksa iznosilo od<br />20% do 80%. Porast fluksa do kojeg dolazi<br />postavljanjem statičkog me&scaron;ača u kanal membrane</p><p>uslovljen je uspostavljanjem turbulentnih uslova<br />proticanja i karakterističnog kretanja fluida duž<br />kanala membrane, koja je posledica<br />karakterističnog povezivanja helikoidnih<br />elemenata Kenics statičkog me&scaron;ača.<br />Kako u uslovima recirkulacije napojne sme&scaron;e,<br />tako i u uslovima koncentrisanja, vrednost<br />relativne specifične potro&scaron;nje energije zavisi skoro<br />isključivo od vrednosti protoka napojne sme&scaron;e. Sa<br />povećanjem protoka specifična potro&scaron;nja energije<br />u prisustvu statičkog me&scaron;ača naglo raste i<br />relativno povećanje protoka nije dovoljno da bi<br />kompenzovalo gubitak hidrauličke snage. U<br />opsegu protoka od 80 do 100 L/h su obezbeđene<br />pozitivne vrednosti relativne promene specifične<br />potro&scaron;nje energije, te je upotreba statičkog me&scaron;ača<br />opravdana sa ekonomskog aspekta.<br />Optimizacija eksperimentalnih uslova urađena je<br />postupkom istovremene maksimizacije fluksa<br />permeata u sistemima sa statičkim me&scaron;ačem i<br />relativne promene specifične potro&scaron;nje energije.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />recirkulacije napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri maksimalnoj<br />vrednosti transmembranskog pritiska od 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 6 g/L.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />koncentrisanja napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri vrednosti<br />transmembranskog pritiska od 0,85 do 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 7 g/L.<br />Pored ispitivanja na laboratorijskoj<br />aparaturi, cilj ovog rada je bio i ispitivanje uticaja<br />procesnih parametara na proces mikrofiltracije<br />suspenzija skroba u poluindustrijskim uslovima<br />(na jednokanalnoj i vi&scaron;ekanalnoj membrani<br />srednjeg prečnika pora 200 nm), odnosno &scaron;ireg<br />opseg vrednosti transmembranskog pritiska i<br />protoka suspenzije na pomenute odzive u<br />uslovima koncentrisanja napojne suspenzije.</p> / <p> The aim of this study was to investigate the effect of<br /> process parameters (transmembrane pressure, flow<br /> rate and suspension concentration) on the permeate<br /> flux in the system with and without the presence of<br /> static mixer. Microfiltration of wheat starch<br /> suspensions was performed in recirculation and<br /> concentration mode using ceramic membranes with<br /> different pore size (200 nm and 500 nm). Response<br /> surface methodology was applied for modeling<br /> cross-flow microfiltration of starch suspensions.<br /> During investigation of starch suspension<br /> microfiltration process on membranes with different<br /> pore size diameter (200 and 500 nm) it was<br /> observed that with increasing pore size the permeate<br /> flux declined.<br /> In the experimental range of process parameters,<br /> flux increase had values between 25% and 50% in<br /> recirculation mode, while in concentration mode<br /> this improvement was in range between 20% and 80%. The increase in flux that occurs by placing a</p> <p> static mixer in the membrane channel was caused<br /> by the establishment of turbulent flow conditions<br /> and the characteristic flow of fluid along the<br /> membrane channel, which is a consequence of the<br /> characteristic geometry of Kenics static mixer.<br /> Both in recirculation and concentration mode, the<br /> reduction of specific energy consumption depends<br /> almost exclusively on the value of the suspension<br /> flow rate. Specific energy consumption increased<br /> rapidly with increasing flow rate in the presence of<br /> static mixers and flux improvement is not high<br /> enough to compensate the loss of hydraulic<br /> dissipated power. The flow rate in the range from<br /> 80 to 100 L/h provided positive values of the<br /> reduction of specific energy consumption and the<br /> use of static mixers was justified from the<br /> economical point of view.<br /> Optimization of experimental conditions was done<br /> by a procedure of simultaneous maximization of<br /> permeate flux in systems with static mixers and<br /> reduction of specific energy consumption. Optimal<br /> conditions of the wheat starch suspension<br /> microfiltration in recirculation mode indicate that<br /> the process should be conducted at the maximum<br /> value of transmembrane pressure of 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 6<br /> g/L.<br /> Optimal conditions of the wheat starch suspension<br /> microfiltration in concentration mode indicate that<br /> the process should be conducted when the value of<br /> transmembrane pressure from 0.85 to 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 7<br /> g/L.<br /> Apart from investigations in laboratory conditions,<br /> the aim of this study was to examine the influence<br /> of process parameters on the starch suspensions<br /> microfiltration in the pilot plant (one channel and<br /> multichannel membrane with pore diameter 200<br /> nm) and wider range of transmembrane pressure<br /> and suspension flow rate on the mentioned<br /> responses in concentration mode.</p>

Nonadhesive hydrate slurries have been shown to exhibit low viscosities in a field-scale flow loop when formed under appropriate conditions. The factors that favor formation of low-viscosity hydrate slurries include high Reynolds Number and Capillary Number, and high mass transfer and heat transfer rates. High liquid loading and high superficial fluid velocities are found to be conducive to the formation of low viscosity hydrate slurries. Dispersed bubble flow has been observed to facilitate flowable hydrate slurry production. Alternatively, the formation of nonadhesive hydrates at moderate superficial velocity is possible when a static mixer is used upstream of the hydrate formation location. For certain fields, low-viscosity hydrate slurry technology could eliminate the need for insulation and hydrate inhibitor chemicals (revised version of ICGH 2008 paper 5818) .

Nanoparticles have received special attention over past few years as potential drug carriers for proteins/peptides and genes. Biodegradable polymeric poly (lactic-co-glycolic acid) (PLGA) nanoparticles are being employed as non-viral gene delivery systems for DNA. This work demonstrates a scalable technology for synthesis of nanoparticles capable of gene delivery. Cationic PLGA nanoparticles are produced by emulsiondiffusion- evaporation technique employing polyvinyl alcohol (PVA) as stabilizer and chitosan chloride for surface modification. A sonicator is used for the emulsion step and a static mixer is used for dilution in the diffusion step of the synthesis. A static mixer is considered ideal for the synthesis of PLGA nanoparticles as it is easily scalable to industrial production. The resulting nanoparticles are spherical in shape with size in the range of 100–250 nm and posses a zeta potential above +30 mV, indicating good stability of the colloid with a positive charge to bind to anionic DNA. The mechanism of nanoparticle formation was analyzed using multimodal size distributions (MSD), zeta potential data, and transmission electron microscopy (TEM) images. Several emulsion techniques and dilution effect were analyzed in this work. PVA acts as a compatibilizer for chitosan chloride and dilution of primary emulsion has little effect over the particle size of the PLGA nanoparticles.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The computational fluid dynamics is a technique used for the analysis of fluid flow systems By this technique, it is possible to simulate new geometries of equipments as well as optimize one in use. In this research, we propose the development of new configurations for static mixers. Is proposed 27 simulations were conducted in a 24 factorial planning with 3 central points and 8 axial points, varying the thickness and the depth of the groove and the distance between the grooves, in order to obtain the velocity gradient as response. One could obtain two optimal settings were obtained. Once the machining of the optimal geometry was difficult, modifications were proposed to facilitate the construction of the mixer. So 16 configurations were obtained and the simplest one was built to be coupled to an experimental test system. The simulated and the experimental values of the velocity gradient were compared. One set up two tubular reactor systems with and without the static mixer were built for the experiments to obtain biodiesel. In these experiments, a 23 factorial planning was done, varying alcohol:oil ratio, catalyst concentration and temperature. The static mixer presented the value of the velocity gradients of 2288.93s-1, being 4,01% lower than the value found in the (2384.61s-1). A comparison of the experiments showed that the utilization of the mixer increased the ester conversion. The equation obtained from the empirical model of conversion to ester (Y) had an adjustment coefficient of 0.97 for the smooth tube reactor and 0.94 for the reactor with mixer. / A fluidodinâmica computacional é uma técnica que permite a análise de sistemas envolvendo o escoamento de fluidos. Através desta técnica é possível simular novas geometrias de equipamentos, bem como otimizar os já utilizados. Neste trabalho, propõe-se o desenvolvimento de novas configurações para misturadores estáticos. Foram realizadas 27 simulações de um planejamento fatorial 24 com 3 pontos centrais e 8 pontos axiais variando o comprimento equivalente, a espessura, a altura das saliências e a distância entre cada saliência para obtenção do gradiente de velocidade como resposta. Foram obtidas duas configurações ótimas. Com a dificuldade de usinagem da configuração ótima, foram propostas modificações para facilitar a construção do misturador; assim, 14 configurações foram obtidas e a mais simples foi construída, para ser acoplada a um sistema de testes experimentais. Foram comparados os valores do gradiente de velocidade simulado e experimental. Foram construídos dois sistemas de reatores tubulares com e sem o misturador estático construído para a realização dos experimentos de obtenção de biodiesel. Para estes experimentos foi realizado um planejamento fatorial 23, variando os seguintes parâmetros: razão álcool:óleo; concentração de catalisador e temperatura. O misturador construído apresentou o valor do gradiente de velocidade de 2288,93s-1, sendo 4,01% inferior ao valor encontrado na simulação (2384,61s-1). Após os experimentos foi constatado que com a utilização do misturador a conversão em ésteres é maior. A equação obtida para o modelo empírico da conversão em éster (Y) teve um coeficiente de ajuste de 0,97 para o reator com tubo liso e 0,94 para o reator com misturador.

Les procédés continus par rapport aux procédés batch sont réputés être plus surs, plus économiques et plus sélectifs. Au regard de ces avantages, de plus en plus d'industries opérant traditionnellement en batch s'orientent vers des procédés continus. Si beaucoup de recherches ont été menées dans ce domaine en chimie fine, il n'en est pas de même pour les procédés de polymérisation et plus particulièrement pour le procédé de polymérisation en suspension du chlorure de vinyle. Ce procédé est à l'heure actuelle un des procédés batch les plus aboutis tant il a subi d'améliorations au cours des dernières décennies sur les plan chimiques (recette) et technologiques. Cependant, l'exposition au chlorure de vinyle est extrêmement toxique et le procédé présente notamment toujours des limitations en transfert thermique inhérentes à la technologie batch. De plus, l'étape réactionnelle constitue la seule étape batch du procédé total de production. Eu égard a la formation des grains de PVC au cours de la réaction, le procédé peut-être divise en trois principales étapes : une étape de dispersion liquide-liquide dans laquelle les gouttelettes de monomères (diamètre moyen 30-50μm) sont formées et stabilisées, une étape de réaction qui s'accompagne d'un phénomène d'agglomération contrôlée des gouttelettes de monomères et au cours duquel les particules polymérisant s’avèrent collantes et une pure étape réactionnelle au cours de laquelle la polymérisation est menée jusqu'à la conversion désirée. La présente étude se propose d'identifier les technologies adaptées pour chacune des étapes identifiées. Compte tenu des connaissances actuelles sur le comportement et l'évolution des grains avec la conversion et après une étude bibliographique sur les procédés continus de polymérisation, les technologies choisies dans ce travail sont les mélangeurs statiques et différents design de colonnes pulsées utilisées à co-courant. L'étape de dispersion liquide-liquide a été étudiée a l’aide de trois technologies différentes pour des systèmes de phases modèles. Concernant les mélangeurs statiques, les études ont démontré leur capacité à obtenir des gouttelettes de taille contrôlée et de la taille désirée. Dans la gamme étudiée, aucun effet de la concentration en phase dispersée n'a été démontre sur la taille des gouttes. Le paramètre physico-chimique le plus influent est la tension interfaciale. Celle-ci a d'ailleurs été estimée aux temps courts, correspondant aux temps de séjour (40-100 ms) dans les mélangeurs statiques, en modifiant la technique de la goutte pendante. Les résultats en termes de diamètre de goutte ont été corrélés via les nombres adimensionnels caractéristiques du système et de l'écoulement, à savoir les nombres de Reynolds et de Weber. A la lueur de ces résultats, les mélangeurs statiques ont été installes au pilote industriel pour effectuer des chargements de réacteurs batch de polymérisation. En plus de réduire considérablement les temps de chargement, leur utilisation a montré une meilleure répartition des agents de suspension et de l'initiateur au sein du grain. Ensuite, deux design de colonnes pulsées ont été utilises : la colonne pulsée a disques et couronnes a co-courant ascendant vertical et le COBR (continuous oscillatory baffled reactor, Nitech). Pour le premier design, les influence du matériau de garnissage et de son agencement (type et hauteur), des paramètres physicochimiques (concentration en phase dispersée, tensioactifs) et des paramètres hydrodynamiques (débit total, amplitude et fréquence d'oscillation) sur la taille des gouttes obtenues ont été examinées. Avec le second design, seuls les paramètres hydrodynamiques ont été étudiés. Une corrélation sur la taille des gouttes est proposée en fonction de nombres adimensionnels caractéristiques de ces appareils. Les trois technologies génératrices de la dispersion sont alors comparées en termes d'énergie dissipée et de puissance dissipée. [...] / Continuous processes present the benefit to be safer and more cost saving than batch processes. Many researches have been carried out in fine chemistry but few contributions refer to polymerization. We focus on the vinyl chloride suspension polymerization. This process has been extensively studied in batch with lots of improvement regarding the formulation and the technologies. This polymerization process is highly complex due to the toxic nature of the monomer, the good manage of heat transfer and stirring. Moreover the reaction step remains the only batch step of the PVC production. According to the PVC grain formation, the process can be divided into three steps (i) a liquid-liquid dispersion step in which the monomer droplet (30-50 µm) are generated and stabilized, (ii) a controlled agglomeration step of the reacting droplets exhibiting a sticky behaviour, (iii) a reaction step until the conversion rate is around 80-90% and the particles size is stable. In this study, the different technologies suitable for the different steps are pointed out. Based on the state of the art of the grain behaviour depending on the reaction conversion and on the literature concerning polymerization continuous process, static mixers and different co-current pulsed columns are proposed. Three technologies with different model system were chosen to study the liquid-liquid dispersion step. Static mixers allow the control of the droplet size under turbulent flow. In the range of the operating conditions, the dispersed phase concentration does not have a significant effect on the droplet size. The interfacial tension appears to be the most significant physico-chemical parameters. Correlation to predict the mean droplet size is proposed depending on different dimensionless numbers based on the hydrodynamics and on the systems: the Reynolds and Weber numbers. Given the promising results, static mixers are implemented at pilot scale to load the batch prior to polymerization. Their use demonstrates a noticeable reduction of the loading time and a better homogenisation of the different suspending agents and initiator inside the PVC grain. The two co-current pulsed columns design studied are the discs and doughnuts pulsed column and the COBR (continuous oscillatory baffled reactor, Nitech). For the first one, the effect of the packing materials (type and height), of the physico-chemical parameters (dispersed phase concentration, surfactant) and of hydrodynamic parameters (flowrate and oscillation conditions) on the droplet size are investigated where as for the second one the study is limited to the hydrodynamic parameters. A mean droplet size correlation is proposed based on the characteristic dimensionless numbers. The three continuous contactors used for liquid-liquid dispersion are compared in term of energy dissipation rate. The reaction is carried out in a continuous tubular reactor (the pulsed column). The column is suitable to transport solid-liquid suspension. Vinyl acetate suspension polymerization is performed to demonstrate the feasibility and particularly to study the encrusting and fouling problem. The first results are very promising.

De nombreux produits encapsulés sont utilisés dans la vie quotidienne. Crèmes cosmétiques, peintures, et pesticides en sont quelques exemples. De nos jours, de plus en plus de technologies innovantes mettent en jeu des substances encapsulées. La microencapsulation a permis à de nouveaux « textiles intelligents » de voir le jour, tels que les textiles sur lesquels sont fixées des microcapsules qui libèrent un principe actif amincissant, odorant, hydratant ou encore répulsif pour les insectes. Les microcapsules sont des produits à fortes valeur ajoutée, dont les propriétés sont nombreuses, et délicates à maîtriser toutes à la fois. Si l'étape de formulation a pour objectif de trouver la recette optimale pour répondre le mieux possible au cahier des charges, le type de procédé de fabrication choisi doit garantir une production homogène dans le temps, sans écarts par rapports aux propriétés attendues. L'objectif de ces travaux est de proposer une alternative continue aux procédés batch traditionnellement mis en œuvre pour l'encapsulation par polycondensation interfaciale, coûteux en termes d'investissement et de frais de fonctionnement. L'encapsulation par polycondensation interfaciale est constituée d'une étape d'émulsification suivie d'une étape réactive. Nous proposons un procédé découplant ces deux étapes grâce à deux technologies adaptées aux contraintes hydrodynamiques respectives de chaque étape. Cette étude est réalisée sur la base d'un système modèle espèce encapsulée / membrane polymérique. L'étape d'émulsification est réalisée en mélangeurs statiques en régime turbulent. Des mesures de pertes de charge en écoulements monophasiques ont permis de mettre en évidence l'apparition de ce régime et d'établir des corrélations représentant ces pertes de charge a travers l'emploi des nombres adimensionnels que sont le nombre de Reynolds et le facteur de friction. Concernant l'émulsification, nous évaluons l'influence de différents paramètres sur les performances de l'opération en termes de tailles de gouttes obtenues en fonction du coût énergétique. Nous comparons également les performances de trois designs de mélangeurs statiques commercialisés par la société Sulzer, et corrélons les résultats obtenus en termes de diamètres moyens de Sauter en fonction des nombres de Reynolds et de Weber. L'étape réactive est tout d'abord mise en œuvre en réacteur agité afin d'étudier la cinétique de la réaction, et d'acquérir des temps de réactions qui permettent par la suite de dimensionner le réacteur continu. Enfin cette étape est réalisée dans deux types de réacteurs continus : le réacteur Deanhex, développé et étudié par Anxionnaz et al. (2009), ainsi qu'un réacteur tubulaire en serpentin. Cette dernière étude consiste d'une part à valider le passage au continu à travers la conservation de la granulométrie des gouttelettes de l'émulsion durant la réaction, et la conservation de la vitesse apparente de la réaction. Enfin, les conditions hydrodynamiques favorables présentées par les réacteurs continus permettent d'apporter de nouvelles voies d'intensification au procédé en augmentant d'une part la concentration en capsules dans le réacteur, et en s'affranchissant de l'emploi du tensioactif utilisé pour stabiliser les gouttes de l'émulsion. Ce procédé, proposé pour la production en continu de microcapsules, offre une amélioration en termes de qualité du produit et de coût par rapport aux procédés traditionnels en batch mis en œuvre dans l'industrie. / The aim of the present work is to propose a continuous alternative to batch processes classically used to carry out encapsulation by interfacial polycondensation that represent high investment and working costs. Encapsulation by interfacial polycondensation consists in an emulsification step followed by a reactive step. We propose here a process decoupling these two steps using technologies well adapted to hydrodynamic issues of each step. This study is realised on the basis of model system. The emulsification step is carried out in static mixers under turbulent flow. Pressure drop measurements in single-phase flow enable to highlight this flow regime and to establish correlations representing these pressure drops in terms of dimensionless numbers: the Reynolds number and the friction factor. About emulsification we evaluate the influence of different parameters on the operation performances in terms of mean droplets size as a function of energy cost. We compare the performances of three different Sulzer static mixers and correlate results obtained in terms of Sauter mean diameter as a function of Reynolds and Weber numbers. The reactive step has been first carried out is stirred tank in order to study the reaction kinetics and to acquire reaction times necessary to design continuous reactors. Finally this step has been realised using two continuous reactors: the Deanhex reactor (Anxionnaz et al., 2009) and a coiled tube reactor. This last study consists first in validating the continuous process through the conservation of the emulsion size distribution during encapsulation and the conservation of the apparent kinetics. Finally the favourable hydrodynamic conditions presented by continuous reactors offer new ways of intensification to the process. In fact it is possible to increase the microcapsule concentration in the reactor and to work without surfactant to stabilize the emulsion. This continuous process for microcapsules production offers improvements in terms of product quality and working costs compared to traditional batch process used in the industry

<p>Cilj ovog rada je ispitivanje mogućnosti primene koncepta neuronskih mreža i postupka odzivne povr&scaron;ine za modelovanje cross-flow mikrofiltracije suspenzija kvasca. Drugi cilj je bio ispitivanje pobolj&scaron;anja procesa primenom Kenics statičkog me&scaron;ača kao promotora turbulencije. Primena statičkog me&scaron;ača ispitana je i sa energetskog stanovi&scaron;ta, a ne samo sa aspekta povećanja fluksa permeata. Svi eksperimenti izvedeni su u uslovima recirkulacije i koncentrisanja napojne suspenzije.</p><p>Dobijeni rezultati ukazuju da se pobolj&scaron;anje mikrofiltracije može se ostvariti primenom statičkog me&scaron;ača bez primene dodatne opreme. Tokom eksperimentalnog rada porast fluksa iznosio je između 89,32% i 258,86% u uslovima recirkulacije napojne suspenzije u zavisnosti od odabranih eksperimentalnih uslova, dok je u uslovima koncentrisanja napojne suspenzije porast fluksa imao vrednosti od 100% do 540% u istom eksperimentalnom opsegu.</p><p>Koncept neuronskih mreža daje veoma dobre rezultate fitovanja posmatranih odziva.<br />Pored primene ovog koncepta ispitana je i mogućnost procene uticaja pojedinih<br />eksperimentalnih promenljivih na odzive primenom jednačine Garsona i metode jačine sinapsi koje povezuju neurone. Rezulati ovog ispitivanja u saglasnosti su sa regresionom analizom.</p><p>Za detaljniju analizu uticaja eksperimentalnih promenljivih na posmatrane odzive primenjen je postupak odzivne povr&scaron;ine funkcije. Prvi korak u ovom segmentu istraživanja bio je određivanje uticaja srednjeg prečnika pora membrane na proces mikrofiltracije. Najbolji rezultati dobijeni su za membranu srednjeg prečnika 200 nm, po&scaron;to kod većih prečnika pora dolazi do izraženijeg unutra&scaron;njeg prljanja koje rezultuje manjim vrednostima fluksa permeata tokom proces mikroflitracije.</p><p>Dalja istraživanja usmerena su na ispitivanje uticaja pojedinih eksperimentalnih promenljivih ali i njihovih interakcija za odabranu membranu (srednji prečnik pora 200 nm). Rezultati fitovanja eksperimentalnih podataka dobijeni za jednu membranu bolji su u poređenju sa rezultatima kada su fitovani eksperimentalni rezultati za sve tri kori&scaron;tene membrane. Sa energetske tačke gledi&scaron;ta primećeno je da je najbolje raditi u umerenom opsegu protoka napojne suspenzije. Kao kranji cilj primene postupka odzivne povr&scaron;ine urađena je optimizacija vrednosti eksperimentalnih promenljivih, primenom postupka željene funkcije. Optimalni uslovi rada dobijeni u uslovima recirkulacije napojene suspenzije su transmembranski pritisak 0,2 bara, koncentracija napojne suspenzije 7,54 g/l i protok 108,52 l/h za maksimalne vrednosti specifične redukcije potro&scaron;nje energije. Sa sruge strane u uslovima koncentrisanja napojne suspenzije eksperimentalne promenljive imale su vrednosti transmembranski pritisak 1 bar, koncentracija napojne suspenzije 7,50 g/l i protok 176 l/h za maksimalne vrednosti specifične redukcije potro&scaron;nje energije.</p> / <p>The aim of this work was to investigate<br />possibilities of applying neural network and<br />response surface methodology for modeling crossflow<br />microfiltration of yeast suspensions. Another<br />aim was to investigate the improvement of process<br />using Kenics static mixer as turbulence promoter.<br />Experimental work was performed on 200, 450 and<br />800 nm tubular ceramic membranes. The use of<br />static mixer was also examined from an energetic<br />point of view not only its influence on permeate<br />flux. All experiments were done in recirculation and<br />concentration mode.<br />The results clearly show that the<br />improvement of cross-flow microfiltration of yeast<br />suspensions performances can be done with static<br />mixer without any additional equipment. In<br />experimental work, flux increase had values<br />between 89.32% and 258.86% for recirculation of<br />feed suspension depending on experimental values<br />of selected variables while in concentration mode<br />this improvement was in range between 100% and<br />540% for the same range of experimental variables.<br />Neural networks had excellent predictive<br />capabilities for this kind of process. Besides<br />examination of predictive capabilities of neural<br />networks influence of each variable was examined<br />by applying Garson equation and connection<br />weights method. Results of this analysis were in<br />fairly good agreement with regression analysis.<br />For more detailed analysis of variables influence on<br />the selected responses response surface<br />methodology was implemented. First step was to<br />investigate the influence of membrane pore size on<br />the process of microfiltration. The results suggested<br />that the best way to conduct microfiltration of yeast<br />suspensions is by using the membrane with mean<br />pore size of 200 nm, because bigger mean pore size<br />can lead to more prominent internal fouling that<br />causes smaller flux values.<br />Further investigations of microfiltration<br />process were done in order to investigate influences<br />of variables as well as their interactions and it was<br />done for the membrane with pore size of 200 nm.<br />Results for this membrane considering regression<br />analysis were considerably better compared with<br />results obtained for modeling all three membranes.<br />From the energetic point of view it was concluded<br />that it is optimal to use moderate feed flows to<br />achieve best results with implementation of static<br />mixer.<br />As the final goal of response surface<br />methodology optimization of process variables was<br />done by applying desirability function approach.<br />Optimal values of process variables for<br />recirculation of feed suspension were<br />trasmembrane pressure 0.2 bar, concentration 7.54<br />g/l and feed flow 108.52 l/h for maximal values of<br />specific energy reduction. On the other side for<br />concentration of feed suspension these variables<br />had values of 1 bar, 7.50 g/l and 176 l/h</p>

<p>U radu su ispitane mogucnosti separacaije<br />nesaharoznih jedinjenja ultrafiltracijom iz rastvora<br />B i C &scaron;ecera sadržaja suve materije 60 i 30 ^oBx.<br />Eksperimentalna ispitivanja su izvedena na<br />keramickim membrana sa otvorom pora od 20 i 5<br />nm, bez i sa primenom statickog me&scaron;aca kao<br />promotora turbulencije. Tokom recirkulacije i<br />koncentrovanja napojne sme&scaron;e pracen je uticaj<br />nezavisno promenljivih (transmembranskog<br />pritiska, protoka, temperature i vremena trajanja<br />procesa) na fluks, boju, mutnocu i kvocijent<br />cistoce permeta. Ispitan je uticaj statickog me&scaron;aca<br />na prljanje membrane, na potro&scaron;nju energije i<br />smanjenja proizvodnih tro&scaron;kova. Eksperimentalni<br />rezultati su jasno pokazali da se najveca razlika u<br />vrednosti fluksa permeata rastvora B &scaron;ecera dobija<br />kada se uporedi nacin rada bez i sa upotrebom<br />me&scaron;aca. Ta razlika iznosi 30% na 80^oC, odn. 65%<br />kada se temperatura održava na 70^oC. Pri<br />ultrafiltraciji rastvora C &scaron;ecera, koji sadrži<br />mnogostruko vecu kolicinu nesaharoznih<br />jedinjenja, registruje se brža koncentraciona<br />polarizacija, te se pri istim uslovima postiže za<br />70% manji fluks od fluksa permeata rastvora B<br />&scaron;ecera. Sadržaj saharoze permeata i retentata se ne<br />menja tokom ultrafiltracije, nema merljive<br />retencije saharoze, &scaron;to je presudno za buducu<br />primenu ovog separacionog postupka u industriju<br />&scaron;ecera. Dekoloracija rastvora B &scaron;ecera bez<br />upotrebe me&scaron;aca ?? na nivou 40%, ? postiže se na<br />pritisku nižem od 6 bar i protoku od 250 L/h.<br />Upotrebom me&scaron;aca se efekat dekoloracije<br />pobolj&scaron;ava za oko 60%, i to pri protoku ispod 200<br />L/h. Izdvajanje bojenih materija pri ultrafiltraciji<br />rastvora C &scaron;ecera je prividno manje efikasno, jer<br />ne prelazi vrednost od 25% racunato na napojnu<br />sme&scaron;u, mada se u apsolutnim vrednostima iz<br />rastvora B i C &scaron;ecera izdvoji približno ista kolicina<br />bojenih materija (900 IJ). Ultrafiltracijom se<br />mutnoca napojne sme&scaron;e redukuje za 85%.<br />Ispitivanja prljanja membrane pri ultrafiltraciji su<br />pokazala da koncentraciona polarizacija i<br />formiranje sloja sastavljenog od nesaharoznih<br />jedinjenja na povr&scaron;ini membrane predstavljaju<br />dominantan udeo ukupnog hidraulicnog otpora. U<br />membrani sa otvorom pora 20 nm, tokom<br />ultrafiltracije meduproizvoda f?ze kristalizacije,<br />otpor poraste usled prljanja za 20 &ndash; 50 puta, a u<br />membrani sa otvorom pora 5 nm za 100 &ndash; 300 puta<br />u odnosu na otpor ciste membrane. Kori&scaron;cenje<br />me&scaron;aca je opravdano u intervalu gubitaka<br />hidraulicke snage od 0 &ndash; 7 W, jer se time postiže<br />povecanje fluksa i do 60%. Pri vecim gubicima<br />hidraulicne snage, odn. pri vecim brzinama<br />proticanja, nivo turbulencije u praznoj cevi je<br />znacajan, tako da se i bez upotrebe me&scaron;aca<br />registruju vece vrednosti fluksa. Povecanje stepena<br />koncentrovanja napojne sme&scaron;e sa 1,0 na 1,2 prati<br />smanjenje ukupnih prizvodnih tro&scaron;kova u opsegu<br />od 30 &ndash; 77% kada se proces ultrafiltracije realizuje<br />uz upotrebu me&scaron;aca.</p> / <p>This work presents the study of possibility to<br />separate of non-sucrose compounds from B and C<br />sugar solutions, with a dry matter content of 60 and<br />30 oBx by ultrafiltration. Experimental<br />investigations were performed on ceramic tubular<br />20 and 5 nm pore diameters membranes, with and<br />without kenics static mixer as turbulence promoter.<br />The influence of independent parameters<br />(transmembrane pressure, flow rate, temperature<br />and ultrafiltration time duration) on permetate flux,<br />colour, turbidity and purity during feed<br />recirculation and feed concentration were<br />examined. The efficiency of static mixer was<br />investigated on membrane fouling, on energy<br />consumption and on economical calculations. The<br />experimental results showed that, the greatest flux<br />difference of B sugar solution was obtained when<br />the operation mode was with a static mixer in<br />comparation to the operation mode without one,<br />showing 30% difference at temperature 80 oC and<br />65% at 70 oC. While ultrafiltering the C sugar<br />solution, which contains more non-sucrose<br />compounds, a faster concentration polarization was<br />noticed, thus at the same working conditions 70%<br />less flux was reached in comparison with to the B<br />sugar solution permeate flux. The permeate and<br />retentate sugar content did not changed during<br />ultrafiltration, there is no measurable retention of<br />sucrose, which is important for the implementation<br />of this type of separation into sugar industry. The<br />decoloration of B sugar solution without static<br />mixer is 40%, and can be reached at<br />transmembrane pressure bellow 6 bar and flow rate<br />of 250 L/h. By using a static mixer the decoloration<br />effect is improved for 60%, when flow rate is held<br />bellow 200 L/h. The separation of coloured<br />compounds during ultrafiltration of C sugar<br />solution is apparently less efficient since the value<br />did not reach 25% calculated on feed, even though<br />measured in absolute values the same level of<br />coloured compounds was separated from B and C<br />sugar solution (900 IU). The turbidity of B and C<br />solution was reduced by ultrafiltration for 85%.<br />The examinations of membrane fouling during<br />ultrafiltration showed that the concentration<br />polarization and formation of a non-sucrose<br />compound layer on the membrane surface are<br />dominant parts of the total hydraulic resistance.<br />During ultrafiltration of intermediate products of<br />sugar crystallization using 20 nm pore membrane<br />diameter the resistance increased for 20 &ndash; 50 times<br />due to fouling. Using a 5 nm pore diameter<br />membrane the resistance increased for 100 &ndash; 300<br />times comparing to clean membrane. The use of<br />static mixer is justified when 0 &ndash; 7 W loss of<br />hydraulic power was determined, because in that<br />interval a 60% flux increase was detected. At<br />higher levels of hydraulic power loss, and at higher<br />values of flow rates the turbulency in empty tubular<br />membrane is significant, so even without using<br />static mixers higher values of flux are detected.<br />When a static mixer was used with the increase of<br />volume concentration ratio from 1,0 to 1,2 the total<br />production costs decreased in a range of 30 &ndash; 77%.</p>