Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T05:10:47Z (GMT). No. of bitstreams: 1 Ribeiro_MarinadosSantos_M.pdf: 1906759 bytes, checksum: 068fcf7b154ad2dedadfc296efb7fbde (MD5) Previous issue date: 2005 / Resumo: O leito fluidizado pulsado rotativo (LFPR) tem sido estudado como uma alternativa para a fluidização de materiais que são difíceis de processar em leito fluidizado convencional (LFC). O LFPR é um leito fluidizado convencional modificado pela adição de um disco rotativo com uma abertura 60º abaixo do distribuidor. O disco rotativo assegura uma alimentação cíclica do gás no leito, fornecendo uma força extra para fluidizar as partículas. Tal característica torna o LFPR atrativo para o uso no processo de secagem, pois realça a transferência de calor e massa. No entanto, a freqüência da pulsação do gás no interior do leito depende da freqüência de rotação do disco. O objetivo deste trabalho foi estudar o comportamento fluidodinâmico de partículas secas e úmidas em um LFPR e compará-lo com os resultados obtidos em um LFC. As partículas selecionadas para o estudo foram celulose microcristalina e ácido adípico, e os parâmetros estudados foram: a carga da partícula, a freqüência de rotação do disco e o teor de umidade inicial. Verificou-se que em freqüência da rotação do disco baixa, jorros alternados se formaram, alternado com as regiões de leito fixo. Quando a freqüência da rotação do disco era elevada, o sistema todo fluidizou de uma maneira similar a um leito fluidizado convencional. Constatou-se que pode-se empregar o LFPR para processar materiais que apresentam características coesivas em condições inviáveis em LFC. A velocidade mínima de fluidização para o LFPR foi menor do que a obtida para o LFC, o que evidencia as condições mais fáceis de fluidização no primeiro equipamento e sua aplicabilidade ao processo de secagem / Abstract: The rotating-pulsed fluidized bed (RPFB) has been studied as an alternative for fluidization of materials that are difficult to operate in the Conventional Fluidized Bed (CFB). The RPFB apparatus is a conventional fluidized bed modified by the addition of a rotating plate with a 60º opening just below the distributor. The rotating plate insures a cyclic feed of the fluidizing gas into the bed, providing an extra force to fluidize the particles. This characteristics becomes the RPFB attractive for use in drying process, enhancing heat and mass transfer. In this way, the frequency of pulsed gas purges in the bottom of the bed depends upon the frequency of the rotating disk. The objective of this present work was to study the fluid dynamic behavior of both dry and moist particulate samples in a RPFB and compare with the results from a CFB. Selected samples were microcrystalline cellulose and adipic acid. The parameters used for the study were: particle load, disc rotation frequency and initial sample moisture content. It was possible to verify that when the disk rotation frequency was low, rotating spouts were formed, alternated with fixed bed regions. When disk rotation frequency was high, the total system was fluidized in a manner similar to a conventional fluidized bed. It was observed the RPFB can be used to material with cohesive characteristics, this conditions is not usual to CFB. The minimum fluidization velocity for the RPFB was lower than that for the CFB, which evidences the easier fluidization conditions in the first apparatus and its applicability to drying process / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

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Orientadores: Osvaldir Pereira Taranto, Maria Regina Parise / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-15T00:14:01Z (GMT). No. of bitstreams: 1 Silva_CarlosAlexandreMoreirada_M.pdf: 7935958 bytes, checksum: a7eaf2f609aaa80966fa3a763933b3cf (MD5) Previous issue date: 2009 / Resumo:A operação de fluidização tem sido muito utilizada em inúmeros processos industriais nos setores químicos, alimentício e farmacêutico em função das suas características vantajosas, que possibilitam um contato bastante efetivo entre a fase sólida e a fase fluida. No entanto, as condições de operação destes processos freqüentemente podem conduzir ao fenômeno de defluidização ou até ao colapso total do leito. A manutenção de condições estáveis do regime de fluidização durante processos de recobrimento de partículas em leitos fluidizados também é de fundamental importância, pois o excesso de umidade dentro do leito acaba levando à defluidização. O presente trabalho objetiva aplicar a metodologia de análise espectral Gaussiana dos sinais de flutuação de pressão para monitorar e controlar o fenômeno de defluidização do processo de recobrimento de celulose microcristalina em um leito fluidizado gás-sólido. O trabalho foi realizado em duas etapas: 1) monitoramento dos regimes de fluidização operantes durante a evolução do processo de recobrimento e 2) controle da vazão de ar e da vazão de suspensão utilizando-se controladores PI. Diferentes condições experimentais de massa de celulose, vazão de suspensão polimérica e excesso de velocidade do ar em relação à mínima fluidização na temperatura de 70°C foram estudadas. A evolução da freqüência média Gaussiana mostrou claramente as transições de regimes de fluidização durante o processo e possibilitou a definição de uma faixa de regime estável de 6,0 a 7,0 Hz, que foi empregada como setpoint range dos controladores para manipular os sinais de comando para o inversor de freqüência e para a bomba peristáltica. A aplicação do método de Åström e Hägglund permitiu a obtenção dos parâmetros do controlador PI para o inversor e o método da curva de reação proporcionou uma estimativa preliminar dos parâmetros do controlador PI para a bomba. Ensaios de recobrimento da celulose em malha fechada mostraram que a utilização de um sistema de controle permitiu obter melhores condições fluidodinâmicas do leito em relação ao processo sem controle. Embora quantidades equivalentes de suspensão tenham sido adicionadas em ambos os processos, o regime de fluidização operante com controle era do tipo borbulhante estável, enquanto que sem controle o regime era de leito fixo, mostrando que o objetivo do trabalho em manter condições mais estáveis de fluidização durante o processo foi atingido. / Abstract: The fluidization operation has been used extensively in many industrial processes in chemical, food and pharmaceutical branches, because of its advantageous characteristics that promote an effective contact between the solid and the fluid phases. However, the operational conditions of these processes frequently lead to the defluidization phenomenon or to the total collapse of the particles in the bed. The handling of stable conditions in the fluidization regime during fluidized bed coating processes is very important, because the moisture content excess can cause the defluidization of the bed. The objective of this present work is to apply the Gaussian spectral pressure distribution to monitor and to control the defluidization phenomenon in a fluidized bed coating process using microcrystalline cellulose as fluidizing particles. The work was performed in two stages: 1) monitoring of the fluidization regimes during the development of the coating process and 2) control of the airflow rate and of the coating suspension flow rate using PI controllers. The experiments were carried out varying solid particle mass, coating suspension flow rate and excess air velocity in relation to the minimum fluidization velocity in the temperature of 70ºC. The Gaussian mean frequency evolution showed the fluidization regime transitions and it allowed to define a band of stable regime (6.0 Hz to 7.0 Hz), which was used as a set-point range of the controllers to manipulate the signal of command for frequency inverter and for the peristaltic pump. The application of Åström e Hägglund method allowed obtaining the PI controller parameters to the inverter and the reaction curve method provided an initial guess of the PI controller parameters to the pump. The experiments of microcrystalline cellulose coating in closed-loop showed that the use of a control system allowed obtaining better fluid-dynamic conditions of the bed in relation to the without process control. Although equivalent amounts of suspension have been added to both processes, the fluidization regime with control was kept under bubbling stable, while without control the regime was that of a fixed bed, showing that in order to maintain more stable fluidization during the process was reached. / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Araí Augusta Bernardez Pécora / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-20T23:00:34Z (GMT). No. of bitstreams: 1 Lira_ClaudioSilva_M.pdf: 5375491 bytes, checksum: a37f9efda77abc71b80a10d20833b839 (MD5) Previous issue date: 2012 / Resumo: Os biocombustíveis têm sido utilizados como uma forma de solucionar os problemas relacionados à geração de energia a partir de combustíveis fósseis, por sua contribuição na redução das emissões de gases de efeito estufa e outros poluentes como SO2. O objetivo desta pesquisa é caracterizar a partícula e estudar o processo de conversão térmica de sementes de tucumã-do-Amazonas (Astrocaryum aculeatum) em óleo combustível através da caracterização dos produtos gerados no processo de pirólise rápida em reator de leito fluidizado borbulhante em escala laboratorial. O efeito da temperatura do processo foi analisado, variando-se a temperatura do reator entre 400 e 600°C, mantendo-se constante a velocidade superficial do gás de fluidização e, portanto o tempo de residência dos gases gerados no processo de pirólise. Em todos os testes, areia com diâmetro médio de 180 m foi o material inerte utilizado. As partículas de biomassa alimentadas no reator possuíam diâmetro inferior a 2 mm e os produtos (sólido, líquido e gás) gerados durante o processo foram quantificados e analisados, obtendo-se seus rendimentos em função da temperatura de operação do reator. Os resultados mostraram que a fração líquida apresentou maior rendimento quando a temperatura do reator foi de 500oC, representando 60% (em massa) dos produtos gerados. Nessa condição, o poder calorífico superior do bio-óleo (livre de umidade) foi de 20,22 MJ/kg, no entanto um valor de 30,48 MJ/kg foi obtido para temperatura do reator igual a 550°C, o que indica ter potencial para ser utilizado como biocombustível. O carvão vegetal produzido apresentou o maior poder calorífico superior a 500°C, com valor médio de aproximadamente 32 MJ/kg. A análise do carvão mostrou que o produto poderia ser aplicado como fonte para melhoria do solo assim como aditivo para fertilizante, devido aos teores obtidos de óxidos de Fe, Mg, Ca, K e Na no material. As análises dos gases produzidos mostraram que houve um crescente aumento no teor de monóxido de carbono com o aumento da temperatura do reator e que os gases gerados tem potencial para posterior queima e utilização como geradores de energia / Abstract: Biofuels have been used as a contribution to solve problems related to power generation from fossil fuels, since they contribute to reduce greenhouse gas emissions and other pollutant materials such as SO2. In addition, the use of biomass and organic wastes as fuel in power plants or small thermochemical processes that generate products with higher added values may encourage the development of remote areas. The purposes of this research were the particle characterization and the study of the thermal conversion process of Amazon-tucumã (Astrocaryum aculeatum) seeds into fuel oil through the process of fast pyrolysis in a laboratory scale bubbling fluidized bed reactor. The effect of process temperature was analyzed with variation of reactor temperature between 400 and 600°C, the gas superficial velocity was kept constant, therefore, the residence time of the gases produced in the process. In all the tests the sand presenting a Sauter mean diameter equal to 180 ?m was used as inert material. The biomass presented particle diameter smaller than 2 mm and the products generated (solid, liquid and gas) during the process were quantified and analyzed, obtaining their yields as a function of the reactor temperature. The results showed that the highest value of the liquid fraction (60%wt) was obtained when the reactor temperature was 500°C. At this condition the high heating value of bio-oil (moisture free) was 20.22 MJ/kg, however a value of 30.48 MJ/kg was obtained for the reactor temperature equal to 550°C, indicating the potential for being utilized as biofuel Regarding the biochar, the highest value for its heating value was roughly 32 MJ/kg (HHV), obtained at 500oC reactor temperature. Analysis of charcoal showed that the product could be used as a fertilizing to improve soil amendment, because of the high contents of Fe, Mg, Ca, K and Na oxides in the material. Analyses of the gases produced showed that there were an increasing in the content of carbon monoxide at higher temperatures and that the gases produced have potential for burning and utilization for energy generation / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

La poudre de silicium métallurgique (MG-Si, pureté 99 %) ont été étudiées, en se focalisant particulièrement sur les particules fines (taille comprise entre 1 et 10 μm) Ce matériau est utilisé dans l’industrie siliconière pour la synthèse directe du diméthyldichlorosilane et est obtenu par broyage de blocs de silicium. Les propriétés de cette poudre sont cruciales pour le procédé industriel, à la fois en termes de surface spécifique, composition chimique et coulabilité. Comprendre l’influence des particules fines, qui dégradent la coulabilité, et leur origine au cours du broyage est donc d’une importance cruciale. Une nouvelle caractérisation, chimique et cristallographique, des poudres de MG-Si montre que les particules fines sont en moyennes moins chargées en éléments d’alliage que les particules plus grosses. La structure cristalline du silicium est inchangée au cours du broyage, sauf pour les particules superfines (taille inférieure à 1 μm). Celles-ci présentent des zones amorphes : cela montre qu’elles sont soumises à des contraintes plus importantes au cours du broyage, comme cette transformation étant obtenue au-delà d’un seuil de pression. Le comportement du MG-Si en broyage a été étudié pour la première fois. A l’échelle de la particule unique, il est confirmé que les fissures suivent une propagation transgranulaire. De plus, des particules fines peuvent être produites au cours d’un unique événement de broyage, en raison de l’activation simultanée de multiples systèmes de fissures qui peuvent brancher entre elles. La taille critique en-deçà de laquelle la déformation plastique est énergétiquement plus favorable que la propagation de fissure a été estimée à environ 1 μm par une méthode basée sur l’indentation. Ces deux résultats sont cohérents avec la répartition des éléments d’alliages en fonction de la taille de particule. A l’échelle multiparticulaire, une étude pilote en broyeur à tambour tournant a été menée. Les résultats de cette étude ne sont pas disponibles dans cette version publique du manuscrit. Veuillez vous reporter au manuscrit complet. Les conséquences sur la coulabilité de la présence de particules fines dans la poudre de MG-Si produite par broyage ont été caractérisées par mesures d’angle de repos, de dynamique de compaction et en fluidisation. En particulier, un nouveau comportement d’élutriation a été identifié et décrit : l’élutriation séquentielle se produit lorsque des particules fines sont initialement présentes dans le lit fluidisé et se caractérise par l’envolement d’abord des inférieures à environ 30 μm puis seulement des particules de taille supérieure. Ce comportement n’est pas observé en l’absence de fines dans le lit initial. L’explication de ce phénomène pourrait se trouver dans la formation de clusters polydisperses, formés seulement en présence de particules fines. En parallèle de l’élutriation séquentielle, des mesures électrostatiques avec un électromètre externe à la colonne ont montré la présence de potentiels très importants (10 kV), dont le signe correspond à la gamme de taille de particules envolées. Ceci suggère que l’adhésion au sein des clusters pourrait être électrostatique. / Metallurgical-grade silicon (MG-Si, 99 %) powders were extensively investigated, particularly focusing on the fine particles (whose size is between 1 and 10 μm) comprised in these powders. This material is a reactant widely used in the silicones industry for the Direct Synthesis and is obtained by size reduction of millimetric silicon lumps. Powder properties are major stakes of the industrial process. Smaller sizes favor high specific surfaces and high rates of production, but can decrease the lowability, thus inducing poor heat evacuation resulting in hot spots and a decrease in selectivity. Such lowability issues are particularly associated with fine particles, hence understand the generation of these particles during grinding is of critical importance. New chemical and crystallographic characterization of MG-Si is presented, showing that fine particles contain on average less alloying elements than larger particles, yet their crystallographic structure is preserved through grinding. On the contrary, superfine particles (smaller than 1 μm) exhibit amorphous zones: this transformation is pressure induced, showing that these particles experience larger stresses during the grinding step. The behavior of MG-Si in grinding mills has been studied for the first time. At the single particle level, it has been confirmed that transgranular fracture is preferred in MG-Si. Moreover, fine particles can be produced from a single fracture event, due to multiple crack propagation and branching. The critical size under which plastic deformation preferentially occurs over fracture has been evaluated to be approximately 1 μm. These two facts are consistent with a lower level of impurities in fines, yet remaining crystalline, and with superfines exhibiting amorphous areas. At the multiple particle level, pilot scale batch milling experiments have been performed. The results are not included in this public version of the manuscript, please refer to the full manuscript. The consequences of the presence of fine particles in ground MG-Si powder on lowability has been assessed by means of angle of repose, compaction tests and fluidization experiments. A new elutriation behavior has been observed and characterized: for naturally ground MS-Si powders (including fine particles), particles smaller than 30 μm are entrained first, then only larger particles. This was not the case in absence of fine particles. The explanation may probably lie within the presence of polydisperse clusters, formed only in presence of fine particles. Parallel to this elutriation behavior, electrostatic measurements with an external electrometer showed that high potential with sign correlated with the type of particle elutriated are attained during elutriation. This may suggest that electrostatics is responsible for cluster formation.

The multi zone fluidized bed reactor instantaneously creates several chemical/physical environments in a single reactor vessel. Effective solid circulation across zones can be achieved by tuning the reactor geometries, solid properties, and operating conditions. However, there is limited research for this innovative reactor concept beyond the laboratory scale, among which a better understanding of the complex fluid dynamics, dominating the solid circulation in different zones, is a basis. This work aims to propose a new method to capture the fluid dynamics of a pilot MZFBR by laboratory measurements with validation from theoretical analysis and simulation. Toward this goal, we first performed particle characterizations, and fluidization testing experiments in a laboratory scale fluidized bed reactor and a pilot scale multi zone fluidized bed reactor at ambient conditions to study the development of fluidization regimes. Then we compared the minimum fluidization velocity with argon and air between the experimental measurements and theoretical calculation results and proposed a modified Ergun equation, which better fits our system. Finally, we conducted computational particle fluid dynamics simulations for the pilot multi zone fluidized bed reactor with the Ergun equation and our modified equation and compared the results against previous experimental observations. Simulations display that the prediction of pressure drop in the pilot scale multi zone fluidized bed reactor with the proposed Ergun equation is similar to that of the original equation, with a relative deviation of around 3%. However, the modified equation captured the bubbling fluidization behavior as the experiment, while the Ergun equation predicted a smooth fluidization without any bubbles. The better agreements validated both our workflow of estimating the fluidization behavior in a pilot multi zone fluidized bed reactor from laboratory measurements and the simulation strategy.

As a carbon neutral and renewable source of energy, biomass carries a high potential to help sustain the future energy demand. The co-firing of coal and biomass mixtures is an alternative fuel route for the existing coal based reactors. The main challenges associated with co-firing involves proper understanding of the co-firing behavior of blended coal-biomass fuels, and proper understanding of advanced gasification systems used for converting such blended fuels to energy. The pyrolysis and combustion behavior of coal-biomass mixtures was quantified by devising laboratory experiments and mathematical models. The pyrolysis-combustion behavior of blended fuels was quantified on the basis of their physicochemical, kinetic, energetic and evolved gas behavior during pyrolysis/combustion. The energetic behavior of fuels was quantified by applying mathematical models onto the experimental data to obtain heat of pyrolysis and heat of combustion. Fuel performance models were developed to compare the pyrolysis and combustion performance of non-blended and blended fuels. The effect of blended fuel briquetting was also analyzed to find solutions related to coal and biomass co-firing by developing a bench scale fuel combustion setup. The collected data was analyzed to identify the effects of fuel blending and briquetting on fuel combustion performance, ignitability, flammability and evolved pollutant gases. A further effort was made in this research to develop the understanding of fluidized bed hydrodynamics. A lab scale cold-flow fluidized bed setup was developed and novel non-intrusive techniques were applied to quantify the hydrodynamics behavior. Particle Image Velocimetry and Digital Image Analysis algorithms were used to investigate the evolution of multiple inlet gas jets located at its distributor base. Results were used to develop a comprehensive grid-zone phenomenological model and determine hydrodynamics parameters such as jet particle entrainment velocities and void fraction among others. The results were further used to study the effect of fluidization velocity, particle diameter, particle density, distributor orifice diameter and orifice pitch on the solid circulation in fluidized beds. / Ph. D.

L'objectif de cette étude est de comprendre et de modéliser la phénoménologie du transport vertical dense descendant de particules de la classe A de la classification de Geldart. Dans un premier temps, une étude expérimentale est réalisée sur une maquette en statique (absence de circulation de solide) dans le but de déterminer expérimentalement l'effet des paramètres opératoires sur les grandeurs caractéristiques de la défluidisation des particules de FCC : vitesses de sédimentation, porosité de la phase dense, temps caractéristiques…. Ces données sont nécessaires pour l'étude de l'écoulement gaz/solide dense vertical descendant. La simulation numérique en 2D de la défluidisation est effectuée et les prédictions sont comparées aux données expérimentales. Dans un deuxième temps, des essais sur une maquette permettant de reproduire les phénomènes observés industriellement dans les écoulements denses verticaux descendants de particules sont entrepris. Les observations visuelles complètent les mesures de pressions locales obtenues le long de l'écoulement à différentes conditions avec et sans injection de gaz d'aération. L'étude expérimentale consiste à : - déterminer les limites des différents régimes en termes de débit surfacique de solide et de débit d'aération ; - établir les propriétés de l'écoulement dans les différents régimes. Dans un troisième temps, les propriétés des écoulements de différents régimes sont étudiées et modélisées par une approche monodirectionnelle du type bulle-émulsion. / The objective of this study is to understand and model the phenomenology of the vertical downward dense transport of class A particles of the Geldart classification. Initially, an experimental study is conducted on a static fluidized bed (no flow of solid) in order to determine experimentally the effect of operating parameters on the defluidization properties of FCC particles, such as, sedimentation rates, dense phase porosity, characteristic times ... These data are needed to study gas/solid dense downward flow. 2D numerical simulations of defluidization are performed and the predictions are compared with experimental data. In a second step, experiments are undertaken in a pilot unit able to reproduce the gas/solid dense downward flow phenomena observed in industrial units. Visual observations complement the local pressure measurements profile obtained for the different flow conditions with and without external injection of gas. The experimental study is conducted to: - determine the boundaries of different flow patterns in terms of solid mass flux and gas flowrate; - establish flow properties in different flow patterns. Finally, flow properties of the different patterns are studied and modelled by a monodimensional bubble/emulsion approach.

O objetivo desta dissertação consiste em aprofundar o entendimento dos mecanismos que controlam o atrito lateral sob arrancamento de estacas instaladas por fluidização em areia. A técnica de instalação é estudada como uma alternativa para a utilização de estacas torpedo na fixação de plataformas offshore. Trabalhou-se em laboratório com o arrancamento de estacas metálicas circulares em modelo reduzido. Foram utilizados três diâmetros de estacas modelo, simulando três diferentes escalas: 14 mm (1:76), 16,2 mm (1:67) e 21,3 mm (1:50). Foram realizados 8 ensaios de arrancamento (24 horas após a fluidização) em estacas modelo instaladas por fluidização em solo arenoso com densidade relativa de 50% e submetido à sobrecarga de 2,236 kPa. Foram também realizados 17 ensaios de arrancamento em estacas modelo pré-instaladas (sem fluidização) em areia com densidade relativa de 30%, simulando uma instalação sem perturbação do solo, uma vez que esta é a densidade relativa aproximada que a areia atinge após o processo de fluidização. Os resultados foram comparados com pesquisas anteriores de arrancamento de estacas instaladas por fluidização em areia. Para um aumento médio de 2 vezes a tensão vertical efetiva nas estacas modelo instaladas por fluidização com sobrecarga, observa-se um ganho médio de 1,8 na resistência. O coeficiente de empuxo lateral de serviço para estes ensaios não apresentou diferenças significativas em relação ao mesmo tipo de ensaio sem sobrecarga. As estacas instaladas por fluidização com sobrecarga e estacas pré-instaladas (sem perturbação) apresentam valores de constantes e independentes das profundidades instaladas, com respectivas médias de 0,15 e 0,31. O valor de parece aumentar com o tempo para as estacas fluidizadas (efeito setup) devido à reconstituição das tensões radiais. Os valores de estacas cravadas em areia densa diminuem seu valor com o aumento da profundidade instalada (e da tensão efetiva média atuante), por restrição de dilatação, tendendo ao valor de encontrado para ensaios pré-instalados realizados neste trabalho. / The main goal of this study is to deepen the understanding of the shaft friction behavior under tension loads of piles installed by fluidization in Osório sand. The installation technique is studied as an alternative for the use of torpedo piles in offshore platforms anchoring. This work was done in laboratory with metallic circular piles in reduced model. Three diameters of model piles were used, simulating three different scales: 14 mm (1:76), 16,2 mm (1:67) and 21,3 mm (1:50). Eight pullout tests (24 hours after fluidization) were carried out on model piles installed by fluidization in sandy soil with a relative density of 50% and subjected to a surcharge of 2,236 kPa. Eighteen pullout tests were performed on pre-installed (non-fluidized) model piles in sand with a relative density of 30%, simulating an installation without soil disturbance, since this is the approximate relative density reached after the process of fluidization. The results were compared with previous studies of pullout resistance of fluidized piles in sand. For an average increase of 2 times the vertical effective stress in the model piles installed by fluidization with surcharge, an average increase of 1,8 times is observed in the pullout resistance. The lateral earth pressure coefficient on the pile shaft for these tests did not show significant differences in relation to the same type of test without surcharge. For tests installed by fluidization and pre-installed tests (without soil disturbance), remains constant and independent of the installed depths, with respective averages of 0,15 and 0,31. The value seems to increase with time for fluidized tests (setup effect) due to the reconstitution of the radial tensions. The values for pullout tests in driven model piles in dense sand decrease their value with the increase of the installed depth (and the increase of the vertical effective stress), by restriction of the expansive behavior, tending to the value found for pre-installed tests carried out in this work.

Filtered two-fluid models used to perform large scale simulations of gas-solid fluidized flows of industrial risers require closures for filtered parameters such as filtered and residual stresses, and interphase interaction forces mainly effective drag. Closure models for those filtered parameters may be derived by averaging over results of highly resolved simulations with microscopic two-fluid modeling. This work is a contribution in that context. Recent models for filtered parameters have been written as functions of filter size, filtered solid volume fraction, and filtered slip velocity. A recent study showed that macro-scale variables like domain average solid volume fraction and gas Reynolds number also significantly affect the filtered parameters. In the current work, in addition to these filtered and macro-scale variables, the effects of two new variables over the filtered parameters are investigated: filtered solid kinetic energy and sub-grid gas turbulence. It is shown that the filtered solid kinetic energy should be accounted for in the concerning correlations, thereby improving accuracy. Regarding gas turbulence, literature shows it has no significant effects on the motion of high Stokes particles. Extending on literature, this work investigates the sub-grid gas turbulence effects on meso-scale structures formed of high Stokes particles. Results showed that sub-grid gas turbulence has no significant effects on the meso-scale structures and corresponding filtered parameters. The open source code MFIX was used for all simulations. Ranges of dilute concentration of solid and gas Reynolds number typical of riser flow regimes were considered. A modified two-fluid model with microscopic formulation was used. The sub-grid gas turbulence was generated by means of a forcing function procedure which was implemented in the physical space, over the gravitational term of the momentum conservation equation of the gas phase. First, numerical simulations of the gas phase alone were performed, accounting for literature available data, in order to set a turbulent gas field and calibrate the turbulence intensity. Then, the forcing function was introduced in to the two-fluid model and various gas-solid flows were simulated. While the current results show the necessity of accounting for additional variables in the filtered parameter correlation, they also make it clear the necessity of further developments that are required in the search for better accuracy. / Modelos filtrados de dois-fluidos usados em simulações de grandes escalas de escoamentos fluidizados de gás-sólido de risers industriais exigem fechamentos para parâmetros filtrados tais como as tensões filtradas e residuais, e forças interativas interfases, principalmente arrasto efetivo. Modelos de fechamento para estes parâmetros filtrados podem ser gerados a partir de procedimentos de media aplicados sobre resultados de simulações altamente resolvidas com modelagem microscópica de dois-fluidos. Este trabalho é uma contribuição neste contexto. Modelos de fechamento recentes para parâmetros filtrados tem sido formulados em função de tamanho de filtro, fração volumétrica de sólido filtrada, e velocidade de deslizamento filtrada. Estudo recente mostrou que variáveis de macro-escalas como fração volumétrica de sólido e número de Reynolds de gás médios no domínio também afetam significativamente os parâmetros filtrados. No presente trabalho, além dessas variáveis filtradas e de macro-escala, os efeitos de duas novas variáveis sobre os parâmetros filtrados são investigados: energia cinética filtrada do sólido e turbulência submalha do gás. Em relação à energia cinética filtrada do sólido, mostra-se que a sua consideração refina as correlações em questão, contribuindo assim para melhor acuracidade. Com relação à turbulência do gás, a literatura mostra que não tem efeitos significativos no movimento de particulados de elevados números de Stokes. Acrescentando à literatura, este trabalho investiga os efeitos da turbulência sub-malha do gás sobre estruturas de meso-escala formados de particulados de elevados números de Stokes. Os resultados mostraram que a turbulência sub-malha do gás não tem efeitos significativos sobre estruturas de meso-escalas e parâmetros filtrados correspondentes. O código aberto MFIX foi usado para todas as simulações. Faixas de concentração diluída de sólido e número de Reynolds típicos de escoamentos em risers foram considerados. Um modelo modificado de dois fluidos com formulação microscópica foi utilizado. A turbulência sub-malha do gás foi gerada por meio de um procedimento de \'forcing function\' que foi implementado no espaço físico, sobre o termo fonte gravitacional da equação de momentum da fase gás. Primeiramente, simulações numéricas da fase gás foram realizadas separadamente, levando-se em conta dados disponíveis na literatura, a fim de gerar um campo de gás turbulento e calibrar a intensidade de turbulência. Posteriormente, a \'forcing function\' foi introduzida no modelo de dois-fluidos e vários escoamentos de gás-sólido foram simulados. Enquanto os resultados obtidos mostram a necessidade de consideração de variáveis adicionais para correlação de parâmetros filtrados, também deixam claro a necessidade de desenvolvimentos mais aprofundados na busca de melhor acuracidade.