Dissertations / Theses on the topic 'Granulation'
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1
Lee, Kai Teck. "Continuous granulation of pharmaceutical powder using a twin screw granulator." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4002/.
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Twin screw extruder (TSE) has been studied extensively as a granulator because it allows continuous processing. Initial work was carried out by comparing the TSE with conventional granulator shows that the mechanism of TSE granulation is different from conventional granulation with the absence of the consolidation stage. PEPT was also utilised and it reveals that the flow stream of the material is not only due to the conveying capacity but also the granulator fill, in particularly for the 90o mixing zone which is believed to be a dispersion type of mechanism driven by the granulator fill gradient. Residence time distribution was measured and simulated by fitting the experimental data using a continuous stirred tank reactors model. The model describes the experimental curves reasonably well when a plug flow fraction was considered. Generally the mean residence time (MRT) of the system is proportional to the mixing zone angle and is inversely proportional to the screw speeds and flowrate. A study using the variance reduction ratio demonstrates that the TSE granulator used in the present study is able to remove the feed instability given that the ratio of the frequency of the input stream fluctuation to the MRT is high.
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Vialatte, Lilian. "Mécanismes de granulation : application à la granulation par agitation mécanique." Compiègne, 1998. http://www.theses.fr/1998COMP1097.
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Notre travail s'est fixé deux objectifs principaux, d'une part, de mieux comprendre les mécanismes de granulation, et d'autre part, de dégager la signature technologique du mélangeur rapide. L'outil de granulation choisi est un mélangeur à taux de cisaillement élevé Lödige d'échelle laboratoire. Plusieurs systèmes poudre-liant ont été étudiés : deux granulométries d'une même poudre, une alumine SH100 et une alumine SH30, et divers liquides : eau, solutions aqueuses de polyéthyléneglycol, et une solution aqueuse d'un alcool polyvinylique. Nous avons mis en évidence un profil de granulation à 3 "régimes" en phase de pulvérisation quels que soient la nature du couple poudre-liant et les actionneurs du procédé utilisés. L'établissement et la généralisation de tels régimes sont des résultats remarquables. L'effet de la nature du couple poudre-liant et des actionneurs sur le profil de granulation a en effet permis de rendre compte des phénomènes fondamentaux qui gouvernent la granulation. L'existence de régimes de granulation traduit que chaque régime est associé à des mécanismes de granulation différents. Après nucléation des particules primaires (régime 0) apparaît un premier régime dans lequel il n'y a plus création de nouvelles espèces granulées. L'historique de la poudre pendant le premier régime est le résultat d'un équilibre entre des mécanismes qui créent des fines (mécanismes de désagglomération) et un mécanisme qui "consomme" des fines (mécanismes de collage des plus fines particules et des plus petits agglomérats). Les phénomènes qui gouvernent la transition entre le premier et le second régime sont les mécanismes de densification des granulés et de migration du liant à la surface des granulés. Le mécanisme prépondérant dans le deuxième régime est le mécanisme d'enrobage aléatoire des fines sur les autres espèces. Enfin, lorsque les fines ont été entièrement consommées, un troisième régime apparaît dans lequel le mécanisme de croissance mis en jeu est le mécanisme de coalescence préférentielle des petits granulés sur les gros granulés.
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Braumann, Andreas. "Multidimensional modelling of granulation." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609355.
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Yusof, Yus Aniza. "Rolling-mill granulation of powders." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424466.
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Scott, Alison Catherine. "Heterogeneity in high-shear granulation." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621989.
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Chollet, Thierry. "Optimisation des rendements en granulation." Bordeaux 2, 1994. http://www.theses.fr/1994BOR2P077.
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Gaillard, Claude. "Gélatines, pouvoir liant et granulation." Université Joseph Fourier (Grenoble), 1990. http://www.theses.fr/1990GRE18011.
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Склабінський, Всеволод Іванович, Всеволод Иванович Склабинский, Vsevolod Ivanovych Sklabinskyi, Максим Сергійович Скиданенко, Максим Сергеевич Скиданенко, Maksym Serhiiovych Skydanenko, Артем Євгенович Артюхов, Артем Евгеньевич Артюхов, and Artem Yevhenovych Artiukhov. "Підвищення ефективності отримання монодисперсних гранул." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/43421.
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На сьогоднішній день в хімічній промисловості для виробництва гранульованого продукту з розплавів активно використовуються обертові віброгранулятори. Але вони мають деякі недоліки: забивання отворів витікання при диспергуванні рідини з домішками, що спричиняє перетин траєкторії руху крапель та їх об’єднання, порушуючи гранулометричний склад продукту, вони не можуть працювати в широкому діапазоні навантажень по розплаву. У даній роботі розглянуто один із варіантів усунення зазначених недоліків, шляхом підвищення швидкості витікання рідини з отворів пристрою.
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Tan, Hong Sing. "Kinetics of fluidised bed melt granulation." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419292.
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Ai, Qing. "Twin screw granulation : granule property optimisation." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/20916/.
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This thesis aims to design granule properties with narrower size distributions and controlled bulk strength through the optimisation of formulation parameters and processing parameters in twin screw granulation with a consideration of binder in solid and liquid forms, respectively. In this thesis, lactose (soluble) and microcrystalline cellulose (insoluble) were chosen as the objective powders. Hydroxypropyl cellulose was used as the main binding excipient. From a perspective of formulation development, a novel approach to predict the optimal L/S ratio for twin screw granulation was developed through the study of single drop behaviour, which reduces the waste from trial and error in formulation development process, in order to producing the granule with narrower size distribution. In addition, the solid binder particle size in formulation was studied. Through evaluating the binding capability of different sized HPC and sieved lactose, it was found that the solid binder with smaller particle size could achieve better binding capabilities which is important on granule size distribution and strength. Moreover, a new solid binder-micronized lactose was evaluated and examined for twin screw granulation. Due to its instant dissolution rate, it was proved to be excellent in binding capability and also leads to a produce of more uniformed granule for both materials. On the other hand, investigations from processing parameter to design the granule properties was also carried out. At first, granulation temperature, especially the liquid temperature was studied. It was found to be effective to enhance the binding capability of HPC in both forms. In addition, more uniformed granule for both material could be obtained when a high temperature applied, especially when HPC solution was used. In addition, process parameters including screw speed and configurations was studied with a constant materials mass in the barrel (Barrel loading, g). This study clarified the effect of process parameter especially screw speed on granule properties which is quite contradictory in the literature. It was found that similar to the use of kneading elements, the screw speed is quite important in narrowing granule size distribution and enhance granule strength especially when kneading elements were used.
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Defaut, Jean-Luc. "Étude comparative des méthodes de granulation." Nantes, 1985. http://www.theses.fr/1985NANT351P.
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MacGinley, Robert. "Granulation tissue as a vascular graft /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16819.pdf.
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Yu, Xi. "An in-silico model of granulation." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2260/.
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Dhenge, Ranjitkumar. "Twin screw granulation : a detailed study." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2227/.
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Zhai, Hui. "Investigation and application of fluidised hot melt granulation (FHMG) as a novel granulation technique to process pharmaceutical materials." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534688.
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Djuric, Dejan. "Continuous granulation with a twin-screw Extruder." Göttingen Cuvillier, 2008. http://d-nb.info/989861163/04.
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Chua, Kel Win. "Predictive model of fluidized bed melt granulation." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505425.
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This thesis describes the development of a computer model that predicts aggregation behavior in fluidized bed melt granulation (FBMG) processes. In FBMG processes, the molten binder enters at one or more points and is then distributed around the bed, these processes are necessarily spatially inhomogeneous. Current granulation modelling using Population Balance Equations (PBE) adopts a lumped approach, using a single lumped rate constant. This thesis shows how to take account of these spatially distributed processes and then predicted the apparent lumped rate constant. The first half of this thesis presents a series of experimentally validated sub-models to describe time scales of events leading to aggregation. These events are granule-granule collision, droplet-granule collision, binder spreading and binder solidification. Computational Fluid Dynamic using a twin-fluid model is used to calculate granulegranule collision time scale and droplet-granule collision time scales. A Volume of Fluid method is used to calculate binder spreading time scales. A dynamic energy balance is used to calculate binder solidification time scales. Validation of the twin-fluid model is done by comparing fluidized bed pressure time series with experiment. Validation of spreading model is done using high speed images of binder droplet spreading. Validation of solidification model is done using high speed infrared images of binder droplet solidification on glass plate. Generalizations for binder spreading time scale and binder solidification time scale are made, so that these time scales for other FBMG process can be calculated directly, reducing the reliance on computational modelling. Granule-granule collision time scale per particle is in the region of O.Ols. Binder spreading time scale is less than O.OOls~ Binder solidification time scale varies from 0.005s to O.Ols. This wider variation for solidification time scale is caused by the effect of fluidized bed operating temperature. By separation of time scales, we evaluate probability that a granule is wet upon granulegranule collision. Binder contact angle determines the wetted area covered by single droplet. Droplet solidification time scale determines the lifetime of the wetted area. This probability is used to calculate granulation efficiency. Applying granulation efficiency with collision rates allows aggregation rate constants for different process variables in FBMG to be evaluated. Our evaluation found that most aggregation takes place within 5cm of the nozzle. In general the calculated aggregation rate constant is higher than the experimentally measured aggregation rate constant. \Ve attributed the unknown effects of averaging across granule SIze, the probability of liquid bridge survival and probability of solid bridge survival with an apparent probability of survival.
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Campos, Claudio Milton Montenegro. "Physical aspects affecting granulation in UASB reactors." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278700.
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Varghese, Honey. "Modeling De Novo Granulation of Anaerobic Sludge." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5878.
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The enigma of anaerobic sludge granulations is still exciting the minds of both experimental scientists and modeling experts. A unique combination of mechanical, physiochemical and biological forces influence granulation during processes of anaerobic digestion. However, knowledge of potential driving forces of granulation has not been transformed into a comprehensive model of anaerobic granulation. In this computational experiment, we address the role physiochemical and biological processes play in granulation and provide a literature-validated working model of anaerobic granule de novo formation. The model developed in a cDynoMiCs simulation environment successfully demonstrated a de novo granulation in a glucose fed system. The simulated granules exhibit experimental observations of radial stratification: A central dead core surrounded by methanogens then encased in acidogens. Practical applications of the granulation model was assessed on the anaerobic digestion of low-strength wastewater by measuring the changes in methane yield as model parameters were systematically swept. This model will be expanded in the future to investigate the influence of mechanical forces on the de novo granulation and the application of a model to anaerobic digestion of a complex protein-carbohydrate rich feedstock.
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Маренок, Віталій Михайлович, Виталий Михайлович Маренок, and Vitalii Mykhailovych Marenok. "Удосконалення грануляційного обладнання для вдосконалення технології виробництва гранульованих продуктів." Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/40279.
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Артюхов, Артем Євгенович, Артем Евгеньевич Артюхов, Artem Yevhenovych Artiukhov, Андрій Миколайович Демченко, Андрей Николаевич Демченко, and Andrii Mykolaiovych Demchenko. "Вплив динаміки руху дисперсної фази на розміри грануляційних веж." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/43432.
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Гідродинаміка руху висхідного газового потоку і краплі (гранули) в ньому значною мірою впливає на якість готового продукту та розміри сучасних грануляційних веж. Аналіз зовнішніх сил, які діють на дисперсну фазу, і внутрішніх напружень, що виникають в ній, дозволяють спрогнозувати умови її деформації, руйнування, траєкторію руху і час перебування в об’ємі грануляційної вежі. Вибір оптимального гідродинамічного режиму руху суцільної і дисперсної фаз дозволить ефективно використовувати існуючі конструкції грануляційних веж та створювати нові зі зменшеними габаритами .
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Reynaud, Stéphan. "Granulation humide, humidité résiduelle, et validation : étude d'un transfert entre deux appareils évaluant l'humidité résiduelle d'un granulé en cours de production : étuve et thermobalance à source halogène de type HR73." Bordeaux 2, 1999. http://www.theses.fr/1999BOR2P037.
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Maurstad, Ola. "Population Balance Modeling of Agglomeration in Granulation Processes." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-123.
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Agglomeration (the sticking together of particles) is often the major growth mechanism in granulation processes. The population balance equation (PBE) is a mathematical framework that is often applied to systems to describe how the particle size distribution changes as a function of time. Different kinetic terms are included in the PBE to describe the different particle growth mechanisms. In this work, a new kinetic model framework is proposed for the growth mechanism binary agglomeration. Binary agglomeration means that only two particles are involved in an agglomeration event. The generality of the new model framework is an advantage over the previous coalescence kernel framework. It is shown that an existing coalescence kernel model can be expressed by means of the new framework.
The new model framework is then adapted to the special case of fluidized bed granulation (FBG) by proposing/choosing expressions for the three submodels in the model framework. An advantage of the new FBG model is that a maximum number of agglomeration events per unit time can be estimated. This means that the model is one step closer to being used predictively. At the moment, no population balance models can predict granulation processes where agglomeration is the dominant growth mechanism. It is shown that both the new FBG model and an existing model could fit experimental data well, however, the new model reflects the situation that the presence of surface liquid is rate limiting for the agglomeratio process.
Experiments in a laboratory batch fluidized bed granulator were carried out. Samples of the particle size distribution were taken at intervals during an experiment. These data were used to fit the model parameters of the FBG model. The dissertation includes a discussion of the effect of certain operating conditions such as bed temperature and liquid spray rate on a model parameter.
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Nilpawar, A. M. "Kinematics and collision kinetics in high shear granulation." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506744.
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Sooben, Kevin. "Modelling high shear granulation using artificial neural networks." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419923.
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Hodgson, Daniel James Matthew. "Particulate granulation and rheology : towards a unifying perspective." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/23651.
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The mixing of powders and liquids is a process ubiquitous to many industrial, research and household applications, from the production of foodstuffs, pharmaceutical and cosmetic products to the preparation of hot drinks or cement. The final mixed state of powders and liquids can be broadly split into two distinct regimes identified respectively as having low- and high volume fraction, ∅. Low-∅ systems are typified by flowing suspensions whereas samples prepared with high-∅, beyond some threshold value, produce solid agglomerates which are unable to flow. These two regimes are the focus of two separate scientific disciplines; suspension rheology and granulation. Within the field of suspension rheology there has been recent advances in the understanding of a phenomena known as shear thickening, which describes the increase in a suspension's viscosity with increasing applied stress. In this thesis we aim to unify the phenomena of shear thickening and granulation within this new theoretical framework. We study shear thickening and granulation using a well characterised model system developed for this purpose, comprising polydisperse glass particles with a mean diameter of ≃ 7 μm and a glycerol-water mixture (90:10 %vol). We measured the rheological behaviour as a function of applied stress, σ, of suspensions at various volume fractions. We observed shear thickening behaviour, with divergences in the low-stress viscosity, η1(∅), and the high-stress viscosity, η2(∅), at ∅RCP = 0:662 and ∅m = 0:572 respectively. These divergences mark the transition between continuous shear thickening, discontinuous shear thickening and a state in which flow is not possible, with increasing volume fraction. Using a recently developed theory of shear thickening (Wyart and Cates, 2014), we were able to fit our rheological data quantitatively. The WC theory predicts a stress-dependent crossover in the fraction of contacts which are frictional in nature, following a stretched exponential function. In order to improve numerical agreement between our data and the model, we developed a method taking into account the volume-weighted contribution of particle sizes in our polydisperse system. Bulk mixing of the same model system in a custom-built high-shear mixer also exhibited three different mixing regimes with the change in behaviour coinciding with the location of the viscosity divergences, ∅m and ∅RCP, measured in the rheology experiments. For ∅ < ∅m suspensions are formed at both high and low stress; for ∅ ≥ ∅RCP granules are formed at all stresses; for ∅m ≤ ∅ < ∅RCP transient granules are formed, which are solid at high stresses, but can relax to a flowing suspension state at low stress. This transient behaviour is reversible with the application of high stress. This coincidence of viscosity divergence in the rheology measurements and mixing behaviour change in the high-shear mixing strongly suggests that the two phenomena are related. Thus we used the stress-dependent jamming volume fraction, ∅J(σ), predicted by the WC theory, to define the transition between the formation of suspensions and granules. We were able to calculate a quantitative phase diagram, with which the regions of the ∅-σ phase space in which granules or suspensions are formed can be easily identified, in agreement with our high-shear mixer data. Thus, using small-scale rheological measurements, requiring relatively small volumes of sample, we are able to define the parameter space in which granules can be prepared, thus eliminating the need for trial and error granulation experiments in order to define this space. We measured the volume-weighted mean granule size as a function of ∅ in the range ∅m → ∅ ≃ 0:85. Based on our observations of granule structure and measurements of granule size distributions, we modelled the granules as an ensemble of core-shell agglomerates with a log-normal size distribution. The packing in the granule cores was assumed to be ∅J(σ ), i.e. ∅m at high stress and ∅RCP at low stress. Appealing to conservation of mass arguments, our model predicts that the mean granule size decreases with increasing volume fraction and stress, in quantitative agreement with experimental data.
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Pearson, Judith Margaret Katharine. "The kinetics and modelling of high-shear granulation." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624282.
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Neilson, Hilding, and Richard Ignace. "Convection, Granulation, and Period Jitter in Classical Cepheids." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/6243.
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Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 min in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present a model of random hot spots that generate a localized flux excess that perturbs the Cepheid light curve and consequently the pulsation period, which is consistent with the observed jitter. This result demonstrates how important understanding convection is for modeling Cepheid stellar structure and evolution, how convection determines the red edge of the instability strip, and just how sensitive Cepheid light curves are to atmospheric physics.
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Calogerà, Giacomo <1976>. "An Investigation Into the Pharmaceutical Melt Granulation Technology." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2939/1/Caloger%C3%A0_Giacomo_tesi.pdf.
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Calogerà, Giacomo <1976>. "An Investigation Into the Pharmaceutical Melt Granulation Technology." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2939/.
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Del, Bene Luca <1988>. "Virtual prototyping of pharmaceutical granulation and coating equipment." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8356/1/PhD_Thesis_Luca_Del_Bene_XXX_AMS.pdf.
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A virtual prototyping methodology for pharmaceutical granulation and coating has been developed. Application of the Multiphase Particle In Cell method (MP PIC) allowed to simulate two phases gas solid flow that occurs in granulation and coating equipment. The computational performance of MP PIC model is very high. The use of CPFD® Barracuda VR™, which implements the MP PIC model, was validated against literature experimental and CFD DEM data, showing its critical points. Barracuda VR™ overestimates the particle transport, but, at the same time, it captures the major trends in the considered physical quantities. This makes Barracuda VR™ a valid instrument to conduct relative comparative analysis, while it is considered less reliable in the estimation of absolute performance values. The application of Barracuda VR™ was evaluated using a Wurster coater for pharmaceutical application. It was found that an air flow rate equal to 800 Nm3/h in the considered machine allows a best performance measured in terms of coating distribution homogeneity on pellets. Several virtual prototypes were modeled to obtain a rotating fluidized bed in a static geometry (RFB SG), called “Spin Flow”. The spin flow fluidized bed (SFFB) must be adapted to perform both granulation and coating processes. Virtual experiments were made, using Barracuda VR™, by varying the air flow rate at the different inlets of the prototypes, but keeping the total air flow rate constant and equal to the best one found for the Wurster process. It was found that one virtual prototype, i.e., the one with four lateral inlets, was good to obtain a spin flow fluidized bed with small particles, as the one used for granulation process, but with the present virtual prototypes it was not possible to obtain a spin flow fluidized bed for larger particles, as the one used for Wurster coating process.È stato sviluppato un metodo per la prototipazione virtuale di macchine per la granulazione e il rivestimento di particelle in ambito farmaceutico. L’applicazione del modello Multiphase Particle in Cell (MP PIC) ha permesso di simulare il flusso bifase gas solido presente in granulatori e rivestitori con prestazioni computazionali molto elevate. L’utilizzo di CPFD® Barracuda VR™ è stato validato su dati sperimentali e dati di simulazioni CFD DEM presenti in letteratura mostrando le sue criticità. La tendenza a sovrastimare il trasporto di particelle, ma allo stesso tempo la capacità di catturare l’andamento delle grandezze fisiche considerate, fanno di Barracuda VR un ottimo strumento per analisi comparative, mentre è considerato meno affidabile per stimare valori e performance assoluti. L’applicazione di Barracuda VR è stata valutata su un rivestitore Wurster per applicazioni farmaceutiche. È stato possibile valutare che una portata d’aria di 800 Nm3/h permette la migliore performance in termini di omogeneità di distribuzione del rivestimento sulle particelle. Diversi prototipi virtuali sono stati modellati per ottenere un letto fluido rotante in una geometria statica (RFB SG), detto “Spin Flow”. Il letto fluido di tipo spin flow (SFFB) deve essere adattabile sia a processi di granulazione che a processi di rivestimento. Sono stati condotti degli esperimenti virtuali, usando Barracuda VR™, variando la portata d’aria agli ingressi dei prototipi virtuali, ma mantenendo la portata d’aria totale costante e uguale a quella trovata per il processo Wurster. Questi esperimenti virtuali hanno evidenziato che un prototipo virtuale, ovvero quello con quattro ingressi laterali, ha reso possibile ottenere un letto fluido spin flow con particelle piccole, tipiche della granulazione, ma con i presenti prototipi non è stato possibile ottenere un letto fluido spin flow per particelle più grandi, tipiche dei processi di rivestimento Wurster.
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Rosso, Michel. "Conduite automatisée de procédés à variables floués commandés à partir de règles." Nancy 1, 1990. http://www.theses.fr/1990NAN10343.
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L'étude concerne l'automatisation d'une installation industrielle de granulation d'engrais. Une étude bibliographique montre tout d'abord la pauvreté des travaux déjà réalisés dans ce domaine, ceci en raison de la complexité et de la méconnaissance des phénomènes de granulation. La régulation de la granulométrie, principal objectif de l'étude, a été atteinte par une succession d'étapes. La stabilisation de l'installation a permis dans un premier temps de créer un nouveau mode de fonctionnement dans lequel les valeurs et les variations des variables mesurées sont représentatives de la granulométrie du produit. La deuxième phase concerne l'estimation de la granulométrie du produit. Le nombre important de variables influentes non mesurées nous a conduit à développer un système de représentation des connaissances basé sur les concepts de la théorie des ensembles flous. La mise au point du régulateur de la granulométrie constitue la dernière étape de cette étude. Une structure de régulateur utilisant le formalisme des règles a été adoptée. L'étude se termine par une analyse du fonctionnement et des performances de l'installation en mode automatique
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Gauthier, Carol. "Étude du mouvement granulaire dans un cylindre en rotation /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1991. http://theses.uqac.ca.
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Vanneste-Ibarcq, Clément. "Study of biomass powders in the context of thermal recovery processes." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0019/document.
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Certains procédés de production d’énergie nécessitent l’utilisation de poudres de biomasse, par exemple la gazéification en réacteur à flux entraîné (RFE). Cependant, les poudres de biomasse ont une mauvaise coulabilité. L’objectif de cette thèse est d’étudier leurs propriétés d’écoulement dans le contexte de la gazéification en RFE, à l’échelle du laboratoire et à l’échelle pilote. A l’échelle du laboratoire, des mesures en tambour rotatif, des tests de cisaillement et des mesures de densité ont été effectués. D’une part, une corrélation est mise en évidence entre la cohésion (issue des tests de cisaillement), la densité et l’angle d’avalanche (tiré des mesures en tambour). Ainsi, un paramètre difficile à obtenir comme la cohésion peut l’être à partir de mesures simples. D’autre part, l’influence de l’humidité sur la coulabilité des poudres de biomasse a été évaluée. L’humidité n’a pas d’effet significatif sous 15 % (en masse, base humide), car l’eau est adsorbée dans la structure de la biomasse ; les particules gonflent et ne sont pas liées par des ponts liquides. Un procédé de granulation humide est proposé. Un liant issu de déchets de biomasse est ajouté à la poudre pour former des granulés d’environ 1 mm. Leur forme sphérique diminue l’entrelacement des particules et leur faible polydispersité diminue le nombre de points de contact. Une amélioration de l’écoulement est observée à l’échelle labo. Une étude énergétique montre que la consommation énergétique du procédé peut descendre jusqu’à 12% du pouvoir calorifique inférieur, ce qui suggère une potentielle rentabilité économique du procédé. Enfin, la caractérisation à l’échelle supérieure est effectuée dans un pilote reproduisant l’injection en RFE. Les résultats montrent le rôle essentiel de la sphéricité et d’une faible polydispersité des particules. L’effet positif de la torréfaction et de la granulation sur la coulabilité est mis en évidenceSome power generation processes require the biomass to be finely ground, such as biomass gasification in entrained flow reactors. However, fine biomass powders are cohesive and present flow issues. This thesis aims to study the biomass powder flowability in the context of the entrained flow gasification process. Biomass powders are characterized both at laboratory scale and pilot scale. Characterization at lab scale consisted of rotating drum measurements, shear tests and density measurements. First, a correlation is found between the cohesion (derived from shear tests), the powder density and the avalanche angle (derived from the rotating drum measurements). Thus, parameters difficult to get such as the cohesion can be obtained with easy to perform measurements. Then, the influence of moisture content on wood powder flowability has been assessed. No significant effect of the water content is found below 15 wt% (wet basis). Below 15%, as water is adsorbed in the biomass structure, the particles swell without being linked by liquid bridges. A wet granulation method is proposed. Biomass waste binders are added to the powder to form granules around 1 mm. The spherical shape lowers the interlocking phenomenon. The low size dispersity of the grains decreases the number of contact points between particles. An improvement of the flowability at lab scale is observed. An energetic study of the granulation process is proposed, showing the energy consumption can be as low as 12% of the biomass Lowest Heating Value. Thus, the process is potentially economically profitable. Finally, characterization at pilot scale is performed with a device mimicking the injection in an entrained flow reactor. The results show the essential roles in the injection step of both the spherical shape and the narrow size distribution of the particles. The positive effect of torrefaction and granulation on the flowability is highlighted
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Yliniemi, J. (Juho). "Alkali activation-granulation of fluidized bed combustion fly ashes." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215624.
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Abstract Biomass, such as wood, binds CO2 as it grows, and is thus considered an environmentally friendly alternative fuel to replace coal. In Finland, biomass is typically co-combusted with peat, and also municipal waste is becoming more common as a fuel for power plants. Wood, peat and waste-based fuels are typically burned in fluidized bed combustion (FBC) boilers. Ash is the inorganic, incombustible residue resulting from combustion. The annual production of biomass and peat ash in Finland is 600 000 tonnes, and this amount is likely to increase in the future, since the use of coal for energy production will be discontinued during the 2020s. Unfortunately, FBC ash is still largely unutilized at the moment and is mainly dumped in landfills. The general aim of this thesis was to generate information which could potentially improve the utilization of FBC ash by alkali activation. The specific objective was to produce geopolymer aggregates by means of a simultaneous alkali activation-granulation process. It was shown that geopolymer aggregates with physical properties comparable to commercial lightweight expanded clay aggregates (LECAs) can be produced from FBC fly ash containing heavy metals. Although the ashes were largely unreactive and no new crystalline phases were formed by alkali activation, a new amorphous phase was observed in the XRD patterns, possibly representing micron-sized calcium aluminate silicate hydrate-type gels. The heavy metal immobilization efficiency of alkali activation varied with the type of fly ash. Good stabilization was generally obtained for cationic metals such as Ba, Pb and Zn, but in common with the results obtained with alkali activation of coal fly ash, anionic metals became leachable after alkali activation. The efficiency of immobilization depended on the physical and chemical properties of the fly ash and was not related to the total content of the element. All the geopolymer aggregates met the criteria for a lightweight aggregate (LWA) as defined by EN standard 13055-1. Their strength depended on the reactivity and particle size distribution of the fly ash. Mortars and concretes prepared with such geopolymer aggregates had higher mechanical strength, higher dynamic modulus of elasticity and higher density than concrete produced with commercial LECA, while exhibiting similar rheology and workabilityTiivistelmä Biopolttoaineet, esimerkiksi puu, ovat ympäristöystävällinen vaihtoehto kivihiilelle, koska ne sitovat hiilidioksidia kasvaessaan. Suomessa biopolttoaineita poltetaan tyypillisesti turpeen kanssa, ja nykyään myös jätteen hyödyntäminen polttoaineena on yleistynyt. Puu, turve ja jätepolttoaineet poltetaan tyypillisesti leijupetipoltto-tekniikalla. Tuhka on polton epäorgaaninen, palamaton jäännös. Puun ja turpeen tuhkaa tuotetaan Suomessa 600 000 tonnia vuodessa ja määrän odotetaan kasvavan, sillä kivihiilen poltto lopetetaan 2020-luvulla. Leijupetipolton tuhkaa ei tällä hetkellä juurikaan hyödynnetä ja tuhka päätyykin pääasiassa kaatopaikoille. Tämän tutkielman päämääränä oli tuottaa tietoa, joka parantaisi leijupetipolton tuhkien hyödyntämistä alkali-aktivaatiolla. Erityisesti tavoitteena oli valmistaa geopolymeeriaggregaatteja yhtäaikaisella alkali-aktivaatiolla ja rakeistuksella. Tutkielmassa osoitettiin, että raskasmetalleja sisältävistä tuhkista valmistettujen geopolymeeriaggregaattien fysikaaliset ominaisuudet ovat vertailukelpoiset kaupallisten kevytsora-aggregaattien (LECA) kanssa. Vaikka tuhkien reaktiivisuus oli matala, ja uusia kidefaaseja ei muodostunut alkaliaktivaatiolla, uusi amorfinen faasi havaittiin XRD-mittauksissa. Uusi amorfinen faasi oli mahdollisesti mikrometrikokoluokan kalsium-aluminaatti-silikaatti-hydraatti-tyyppinen rakenne. Raskasmetallien stabiloinnin tehokkuus vaihteli tuhkien välillä. Kationiset metallit, kuten barium, lyijy ja sinkki, stabiloituivat pääasiassa hyvin, mutta anionisten metallin liukoisuus kasvoi alkali-aktivoinnin myötä. Stabiloinnin tehokkuus riippui tuhkien fysikaalisista ja kemiallisista ominaisuuksista, mutta raskasmetallin kokonaispitoisuudella ei ollu vaikutusta. Kaikki geopolymeeriaggregaatit olivat kevytsora-aggregaatteja standardin EN 13055-1 mukaisesti. Aggregaattien lujuus riippui tuhkan reaktiivisuudesta ja partikkelikokojakaumasta. Geopolymeeriaggregaateilla valmistettujen laastien ja betonien mekaaninen lujuus, Youngin moduuli ja tiheys olivat korkeampia kuin kaupallisella kevytsora-aggregaateilla valmistetut, vaikka niiden reologia ja työstettävyys olivat samanlaisia
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Leong, Jason. "Aerobic granulation with low pH, low alkalinity municipal wastewater." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50666.
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Aerobic granulation was successfully achieved using municipal wastewater with supplemental carbon addition, after a 166 day start-up period. During the start-up period, an increase in biomass particle size was noticed that correlated to a stepwise reduction in settling and decant time. During this time, the granular type formation had a fluffy structure with noticeable filamentous outgrowths. On the 82nd day of start-up, supplemental carbon, in the form of sugar, was added to the feed tank to increase the Organic Loading Rate (OLR) of the system. In addition to an increase in COD, a pH and alkalinity decrease in the feed occurred due to acetogenesis. Soon after the supplemental carbon addition, the biomass developed a denser morphology, with gelatinous, white-coloured, granules appearing on the 166th day.
Although it was shown that aerobic granulation with low pH, low alkalinity municipal wastewater with supplemental carbon was possible, some issues were discovered. These issues include reduced nutrient removal, and lower granule density. The reduction in nutrient removal performance is potentially due to the lack of nitrification/denitrification, and shifting of the microbial ecology to favour Glycogen Accumulating Organisms (GAOs) or heterotrophs over Polyphosphate Accumulating Organisms (PAOs). It is hypothesized that the reduced pH of the influent was the main factor that caused the reduction in nutrient removal. The lower granule density is hypothesized to be a result of the absence of denitrification induced chemical phosphorus precipitation within the granule. As such, the lower granule density results in reduced granule settling velocities and increased Sludge Volume Index (SVI).Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Maxim, Robert E. "Designing granules for abrasive cleaning (using high-shear granulation)." Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/14898/.
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This work investigates the granulation of fine calcium carbonate powder to form microgranules (less than lOOf.lll1). The influence offormulation and operating conditions on granule properties was investigated. This work analyses experimental data using a database approach to relate granulation conditions to granule properties, to fmd propertyto-property relationships and to investigate the influence on the abrasion of Perspex. It was found that the granulation was undertaken in an unstable regime dictated by the need to produce small granules. As a result, it was not possible to achieve reproducibility in making the granules. For the range of granules produced it was difficult to determine variation in abrasiveness within the experimental errors, a detailed error analysis was carried out. A theoretical relationship between strength and porosity is developed and the factors influencing abrasive wear are investigated. Two theoretical models are presented: 1) Impact Failure model and 2) Granule Consolidation model. The impact failure model relates dynamic impact strength to static strength, which enables the prediction of a failure distribution curve (how many particles will fail per hundred impacts as a function of velocity). This is done using a "critical normal impact velocity" determined from the properties of the granule, properties of the impact surface and experimentally measured granule static strength. The granule consolidation model allows the qualitative prediction of the rate and extent of consolidation from granulation conditions. It models the compaction of a granule by descnbing the packing of its primary particles within an imaginary internal granule. Sphere packing is discussed with implications for determining the maximum packing of a primary particle size distribution.
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Prudat, Claire. "Comprimés bioadhésifs d'aminophylline obtenus par granulation par voie humide." Paris 5, 1994. http://www.theses.fr/1994PA05P137.
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Laveix, Michel. "Etude pilote de la granulation en lit d'air fluidisé." Paris 5, 1988. http://www.theses.fr/1988PA05P141.
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Perez-Gandarillas, Lucia. "Dry granulation process and compaction behavior of granulated powders." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2016. http://www.theses.fr/2016EMAC0021/document.
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Les solides divisés telles que les poudres pharmaceutiques nécessitent souvent des processus d'agrandissement de taille par agglomération pour améliorer leur comportement mécanique, notamment la coulabilité. Pour cette raison, le procédé de "granulation en voie sèche" est utilisé dans l'industrie pharmaceutique. Le procédé consiste à comprimer la poudre en la faisant passer entre deux rouleaux séparés par un entrefer, pour produire des plaquettes qui sont ensuite broyées en granulés et comprimés en compacts. Dans ce procédé, l'existence de différents modèles de compacteurs à rouleaux et de systèmes de broyage d’une part, et l'interaction entre les paramètres des procédés et des propriétés des produits (plaquettes, granulés et comprimés) d’autre part, rendent difficile la compréhension des phénomènes et des mécanismes sous-jacents. En particulier, le procédé entraîne une perte de résistance mécanique des comprimés formés à partir de granulés (comparativement à celles des comprimés de poudres non-granulés) et ce phénomène est encore mal compris. Ces aspects sont étudiés dans ce travail de thèse en menant des caractérisations expérimentales et des modélisations numériques permettant de mieux comprendre les modifications micro et macro structurales des poudres mises en forme par granulation sèche. Le but ultime est de progresser dans la compréhension des relations "propriétés des poudres - paramètres des procédés". Enfin, la compréhension des différences de comportement en compression de poudres granulées et non-granulées est menée à l’aide d’une modélisation du comportement dans le cadre de la mécanique des milieux continus poreuxParticulate solids such as pharmaceutical powders often require size enlargement processes to improve the manufacturing properties like flowability. For that reason, dry granulation by roll compaction has been widely used in the pharmaceutical industry. The process consists of compressing powders between two counter-rotating rolls to produce ribbons that will be subsequently milled into granules. The obtained granules are tableted for oral dosage. In this process there are two main limitations: the existence of different designs of the roll compactors, milling systems and the interaction between process parameters and raw material properties are still a challenge and the roll-compaction process leads to an inferior tensile strength of tablets compared with direct compression. These aspects are investigated in this work. In the first part of this thesis, an analysis on the effect of different roll-compaction conditions and milling process parameters on ribbons, granules and tablet properties was performed, highlighting the role of the sealing system and the ribbon density distribution characteristics. In the second part, die compaction of roll-compacted powders, as the last stage of the process, is further investigated in terms of experimental analysis (effect of the granule size and composition and stress transmission measurements) and modelling the compaction behavior of granules
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Cavinato, Mauro. "High shear wet granulation: process understanding and scale up." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427414.
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Among all the powder agglomeration processes, high shear wet granulation is one of the most commonly used techniques. It consists of the agglomeration of different powders through the addition of a granulating fluid and a vigorous mixing. Industries often turn to high shear granulation mainly to avoid segregation of critical components in a powder mixture, improve flowability and compactibility. Despite the great importance of this technique in many industrial activities, it is not totally clear how changes in the initial powder mixture or in process variables can affect the final product properties. Moreover, scale-up of high shear granulators is still difficult to perform.
The present research mainly focuses on the high shear wet granulation of pharmaceutical powders. Particularly, this research aims at closing the gap in understanding the role of primary particle properties (e.g. composition, primary particle size distribution) and process parameters (e.g. mixing speed, liquid flow rate and amount) on the final granule characteristics. Scale-up effects on the powder flow patterns were investigated as well.Tra tutti i processi di agglomerazione di polveri, la granulazione ad elevato shear risulta essere una delle tecniche più usate. Questa tecnica consiste nell‘agglomerazione di diverse polveri dovuta all‘aggiunta di un liquido legante e a un mescolamento energico. La granulazione ad elevato shear è utilizzata principalmente per evitare la segregazione di componenti critici in una miscela di polveri, per migliorare la scorrevolezza e comprimibilità. Nonostante l‘importanza di questa tecnica in numerosi settori industriali, l‘effetto delle proprietà delle polveri e dei parametri di processo sul prodotto finale è ancora poco chiaro. Lo scale up dei granulatori ad elevato shear risulta inoltre ancora difficile da portare a termine. La presente ricerca riguarda la granulazione high shear di polveri farmaceutiche. Lo scopo della ricerca è approfondire la conoscenza sul ruolo delle proprietà delle particelle nella miscela iniziale (p.e. composizione e distribuzione granulometrica) e parametri di processo (p.e. velocità di agitazione, portata e quantità di liquido) nel determinare le caratteristiche del prodotto finale. È stato inoltre analizzato l‘effetto dello scale up sul regime di mescolamento.
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Ярошенко, Д. О. "Моделювання процесу керування грануляцією азотних добрив." Master's thesis, Сумський державний університет, 2021. https://essuir.sumdu.edu.ua/handle/123456789/86704.
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В роботі було визначено контури керування. Створено математичні моделі контурів керування температурою та вологою для дослідження на такі параметри як: час перехідного процесу та точність регулювання. Розроблено систему керування хаосом у процесі гранулювання. Проведено розрахунок оптимального програмного керування для системи рівнянь у програмному пакеті Matlab.
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Locardel-Rietzler, Joëlle. "Recherche de nouveaux liants polymères substituts du PEG dans le procédé de granulation par fusion." Montpellier 1, 2000. http://www.theses.fr/2000MON13510.
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Cheung, Ka-wai Eva. "Granulin expression in basal-like breast cancer." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40738395.
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Smirani, Nadia Marchal-Heussler Laurent Falck Véronique. "Etude cinétique du procédé de granulation humide en mélangeur à haut cisaillement." S. l. : INPL, 2008. http://www.scd.inpl-nancy.fr/theses/2008_SMIRANI_N.pdf.
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Pont, Véronique. "Contribution à l'étude de la granulation des poudres en lit fluidisé : influence des paramètres du procédé et physico-chimiques sur la cinétique de granulation." Toulouse, INPT, 2000. http://www.theses.fr/2000INPT011G.
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Cette etude est consacree a la granulation de particules solides en lit fluidise discontinu par la pulverisation de solutions aqueuses de liants (polymeres ou sels mineraux). Outre la comprehension des phenomenes qui se produisent a l'echelle globale, l'objectif essentiel de ce travail est de mieux comprendre l'influence des phenomenes qui se produisent a l'echelle locale sur la cinetique de croissance et sur la resistance mecanique des agglomerats formes. Nous avons donc etudie l'influence des parametres lies au procede (vitesse de l'air de fluidisation, debit de la solution liante, concentration en liant), des proprietes des particules solides (taille, forme, porosite et solubilite) et la viscosite de la solution liante (entre 1 et 185 cp) sur la cinetique de croissance de taille des agglomerats formes. Afin d'etudier l'influence des parametres lies a la mouillabilite de la surface des particules, la tension superficielle des solutions a ete modifiee entre 72 a 33 mn/m, en utilisant des tensio-actifs et l'angle de contact a ete modifie entre 38\ et des valeurs superieures a 90\ par un traitement chimique conduisant a l'hydrophobisation partielle ou totale de la surface des particules. Nos resultats ont montre qu'une augmentation de la tension superficielle, une diminution de l'angle de contact et de la taille des particules favorisent l'agglomeration des particules, tandis que la viscosite de la solution n'a pas un effet significatif sur la croissance. Ainsi l'agglomeration des poudres en lit fluidise est essentiellement dominee par les forces capillaires (forces statiques) et non pas par la force de dissipation visqueuse. De plus, nos resultats ont montre que la cinetique de sechage des solutions peut aussi avoir un effet
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Lamprecht, Corne. "UASB granulation enhancement by microbial inoculum selection and process induction." Thesis, Stellenbosch: University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1477.
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Thesis (PhD (Food Science))--University of Stellenbosch, 2009.In the absence of anaerobic granules, anaerobically digested sewage sludge is frequently used to seed industrial upflow anaerobic sludge blanket (UASB) reactors. Because of its flocculent nature, start-up with digested sludge instead of granular sludge proceeds much slower and presents various operational problems. Any manner in which the granulation of digested sludge can be enhanced would benefit UASB reactor start-up and application in developing countries such as South Africa. The main objective of this dissertation was to improve granulation and reduce UASB reactor start-up by using pre-treated digested sludge as seed. The sludge was pre-treated based on the batch granulation-enhancement model of Britz et al. (2002). The main aim of the model was to improve extracellular polymer (ECP) production of lactate-utilising populations by applying short-term controlled organic overloading in a mechanically agitated environment. The batch granulation-enhancement (pre-treatment) process was applied to an ECP-producing digester strain, Propionibacterium jensenii S1. Non-methanogenic aggregates were formed when batch units were incubated on a roller-table instead of a linear-shake platform. Larger, more stable aggregates were obtained in the presence of apricot effluent medium. Preliminary batch granulation-enhancement studies confirmed that using the roller-table as mixing system had a positive influence on batch granulation-enhancement. The roller-table showed the most potential for handling larger volumes in comparison to a linear-shake waterbath and linear-shake platform. The addition of 450 mg.L-1 Fe2+ at the start of the study also influenced aggregate numbers positively. These studies revealed that pre-treatment results varied depending on the seed sludge source. A denaturing gradient gel electrophoresis (DGGE) method was applied for the detection of Archaea in digested sludges and UASB granules. In addition, a methanogenic marker containing methanogens important to the granulation process was constructed to aid identification. The positive influence of DMSO and “touchdown” PCR on the elimination of artifactual double bands in DGGE fingerprints were also demonstrated. Results revealed that only one of the four digested sludges tested contained Methanosaeta concilii (critical to granular nuclei formation) while it was present in all the UASB granules regardless of substrate type. Four digested sludges were obtained from stable secondary digesters. DGGE indicated the presence of M. concilii in all sludges. The Athlone 4Sb-sludge was the only sludge which exhibited measurable methanogenic activity during substrate dependent activity testing. The ST-sludge showed the highest increase in volatile suspended solids (VSS) particles ≥0.25 mm2. Laboratory-scale UASB reactor start-up was done with both sludges and start-up proceeded better in the Athlone 4Sb-reactor. Athlone 4Sb-sludge batches were pre-treated in a rolling-batch reactor in the presence of either lactate or sucrose and used to seed lab-scale UASB reactors B (sucrose seed) and C (lactate seed). Start-up efficiencies were compared to a control (Reactor A). Overall Reactor B was more efficient that the control. At the end of the study the Reactor B sludge had a higher methanogenic activity than the control reactor. It also had the highest increase in VSS ≥1.0 mm2. Pre-treatment of digested sludge in the presence of sucrose, therefore, aided granulation and reduced UASB reactor start-up time.
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Smirani, Nadia. "Etude cinétique du procédé de granulation humide en mélangeur à haut cisaillement." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL021N/document.
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Au cours de cette étude du procédé de granulation humide, nous avons mis l’accent sur l’intérêt que présente la distribution du liquide de mouillage dans la définition des propriétés finales de grains. Dans ce cadre, une méthode utilisant un traceur a été développée pour le suivi cinétique de la répartition du liquide de mouillage au cours de la granulation. Une formulation à base d’excipent pharmaceutique a été granulée dans un mélangeur-granulateur à haut cisaillement Mi-Pro. On a pu ainsi montrer que le début du procédé est caractérisé par l’hétérogénéité de la distribution du liquide de mouillage qui se redistribue ensuite selon une loi cinétique d’ordre un. Les propriétés des grains (taille, porosité et observation microscopique) ne deviennent uniformes qu’après une répartition homogène du liquide de mouillage entre les différentes classes de grains. L’étude de l’influence de certaines variables opératoires (vitesse d’agitation, débit et critère de mouillabilité) sur le phénomène de redistribution a été également menée. Par ailleurs, les bilans de population ont été utilisés comme outil de modélisation. Des écritures du noyau d’agglomération ont été proposées en se basant sur la taille des particules et leur teneur en liquide de mouillage. Bien que reproduisant les résultats expérimentaux, les bilans de population présentent certaines limites liées à la difficulté d’intégrer toutes les données de l’étudeIn this study of wet granulation process, we are especially interested in binder liquid distribution as a mean to deduce final granule properties. Then, a tracer method is developed to study binder liquid distribution kinetics during granulation process. Granulation experiments are carried out in high shear mixer Mi-Pro using pharmaceutical excipients. The beginning of the process is characterized by heterogeneous binder liquid distribution. Then, liquid redistribution phenomenon is observed according to a first order model. Granule properties (size, porosity, microscopic observation) are found to be similar when binder liquid is homogeneously distributed among different granule classes. Finally operating conditions influence (speed rate, flow rate and wetting criterion) are discussed. In addition, population balances are used as a tool to model experimental results. Agglomeration kernels are presented depending on particle size and binder liquid ratio. Although experimental results could be satisfactorily modelled, population balances show some limitations related to the difficulty of integrating all the study data
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Chan, Ei Leen. "High shear granulation : a study of blade-granule bed interactions." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/3205/.
Full textAbstract:
Wet granulation, a common unit operation in multiple industries, involves the production of "granules" which are assemblies of primary particles held together by interparticle bonds. Depending on the application, granules with the required attributes such as enhanced strength, flowability, dissolution properties or uniform composition, can be manufactured. It is widely accepted in granulation research that the wet granulation process is comprised of several competing rate processes that dictate the granule growth behaviour and ultimately the granule attributes. In the micro-scale models developed for these rate processes (granule coalescence, consolidation and breakage) and further mapping studies to link formulation, processing and equipment variables to the granule growth behaviour, where the most significant of such work being the "Granulation growth regime map" (Iveson and Litster, 1998b; Iveson et al., 2001b), a fundamental parameter is the external stress exerted on the granules during granulation. The external stress is exerted by the main agitator in the granulator and subsequently transmitted via inter-granule or granule-wall collisions in the system. This thesis studies and characterises the external stress in a high shear granulator, more specifically the impeller blade-granule bed stress. The reserach was divided into the following main parts: A novel, custom-built telemetric impeller stress sensor in the studied granulator was first developed for direct measurements of the instantaneous blade-bed stress. With this system, the steady-state blade-bed stresses were studied for a range of parameters including bed load, granule sieve size and granule/particle density for dry beds and liquid addition for wet beds. The bed surface velocity, measured using high speed recording and analysed with Particle Imaging Velocimetry (PIV), was used to represent the characteristic velocity of the dynamic bed. A correction factor was applied to the theoretical blade-bed stress equation derived based on the imparted inertial stress on continuous bed, which accounted for the increasing bed 'fluidisation' with increasing impeller speed. This enabled much improved predictions of the time-averaged blade-bed stress for the studied parameters, especially at high impeller speeds. The blade-bed stress behaviour during the granulation process was also studied while looking at the evolution of granule attributes. Further characterisation of the steady-state blade-bed stress was carried out by simulating the dynamic dry particle beds in the high shear granulator using the Discrete Element Method (DEM), a widely used simulation method for granular systems. Following the validation of the DEM simulation with the experiments, additional impeller speeds, particle/particle bed properties, impeller geometries and granulator scales were studied from the simulations. A modified correction factor was also applied in the blade-bed stress equation to account for different granulator scales and blade widths. Additionally for the bed characteristic velocity, it was also shown that the bed surface velocity is not the dominant factor for the stress over-prediction from theory with increasing impeller speeds, i.e. the increasing bed 'fluidisation' is the dominant factor. Finally, the temporal values of the steady-state blade-bed stress, bed surface velocity and bed height were studied in terms of the variability/fluctuations, for the different parameters/conditions studied in the experiments and simulations as previously mentioned. More importantly, the results were also related to the identified flow regimes of the granule/particle bed when the impeller speed or Froude number was varied.
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Williams, Jon Christopher. "Initial Investigations of Aerobic Granulation in an Annular Gap Bioreactor." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-04172005-142501/.
Full textAbstract:
This research describes the design, construction, and characterization of a novel annular gap bioreactor. The bioreactor was conceived as a tool for the shear-based control of activated sludge floc particle size in batch and continuous-run experiments. Initial experiments on the feasibility of cultivating aerobic granular sludge in the bioreactor are described. The bioreactor was found to experience turbulent Taylor vortex flow, rather than laminar Couette flow, at all rotational speeds tested. This flow regime is the result of inner cylinder rotation. Despite turbulent flow conditions, the bioreactor was found to behave approximately as a plug-flow device when not aerated, and as a complete-mix reactor when aerated. Floc size control was found to depend on bioreactor rotational speed for two sludges tested, with higher rotational speed leading to smaller particle size. Three experimental attempts at aerobic granular sludge cultivation in the annular gap bioreactor are described in this study. Although none of the three attempts was successful at producing aerobic granules, the experiments allowed critical control issues related to bioreactor operation and influent composition to be identified and addressed. The Bacterial and Eukaryal population dynamics during each run were tracked with denaturing gradient gel electrophoresis and rDNA sequence analysis, using methods developed or streamlined in the course of this research. The foundational work described in this study culminated in the development of a series of protocols and recommendations for the next phase of aerobic granular sludge investigation with this novel annular gap bioreactor.