Thesis (Ph.D.)--University of Tulsa, 1993. / Includes bibliographies.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-03-30T13:38:45Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Mikele Cândida Sousa de Sant'Anna.pdf: 2684133 bytes, checksum: 61e61bb0edcf743d1f2af9c55724a92e (MD5) / Made available in DSpace on 2016-03-30T13:38:45Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Mikele Cândida Sousa de Sant'Anna.pdf: 2684133 bytes, checksum: 61e61bb0edcf743d1f2af9c55724a92e (MD5) Previous issue date: 2015-11-18 / CAPEs / O presente trabalho trata da simulação numérica de um gaseificador de leito fluidizado borbulhante fazendo uso da CFD para o sistema composto por gás-biomassa-areia. Inicialmente, simulou-se os sistemas gás-areia e gás-biomassa. O modelo computacional empregado foi validado empregando-se os resultados experimentais de Taghipuor et al. (2005).A seguir, foi realizado um planejamento fatorial 23, onde se variou a massa específica e o diâmetro da partícula e o percentual de biomassa na fase sólida. Para realizar as simulações foram utilizados os softwares ANSYS CFX 15.0 e ANSYS FLUENT 15.0, adotando-se a abordagem euleriana, com a Teoria Cinética de Escoamento Granular. As seguintes velocidades superficiais do gás foram testadas: 0,03, 0,1, 0,38 0,46 e 0,51 m.s-1. Para o sistema gás-areia, o leito permaneceu fixo nas velocidades de 0,03 e 0,10 m.s-1. Aos 2,50 s de simulação transiente, o leito encontrava-se fluidizado para as velocidades maiores ou iguais a 0,38 m.s-1 e assim permaneceu alcançando um estado pseudo-estacionário. No sistema gás-biomassa, o leito manteve-se fixo apenas na velocidade de 0,03 m.s-1. Dois sistemas foram testados com três componentes (gás-areia-biomassa) diferenciando-se entre si pelos tamanhos das partículas de areia e biomassa. Para grandes diferenças entre estes tamanhos, o sistema apresentou segregação durante a fluidização. No sistema com menor diferença nestes tamanhos, a fluidização ocorreu mais facilmente, uma vez que os efeitos de segregação foram atenuados. Foram obtidos perfis de fração volumétrica do gás, areia e biomassa para as 17 condições do planejamento fatorial, bem como um modelo que prediz a expansão do leito em sistemas fluidizados. O ensaio que apresentou maior altura final do leito (0,50 m), mantendo-se em regime borbulhante, foi aquele com 15% de partículas de biomassa com 375 m de diâmetro e 85% de areia, sendo, portanto, uma condição ótima para a fluidização. / This work has studied a bubbling fluidized bed gasifier though numerical simulation using computational fluid dynamics (CFD) for the system composed of gas - biomass - sand. Initially, gas-sand and gas-biomass systems were simulated. The computer model used was validated employing experimental results from Taghipuor et al. (2005) .Then, a 23 factorial design was employed, where the density, the particle diameter and the the fraction of biomass were varied. All simulations were carried out using ANSYS CFX 15.0 and ANSYS FLUENT 15.0. An eulerian approach coupled to the Kinetic Theory of Granular Flow were used. The following gas superficial velocities were tested: 0.03, 0.1, 0.38, and 0.46 0.51 m s-1. For gas-sand system, a fixed bed was obtained for gas velocities of 0.03 and 0.10 m s-1. After 2.50 s of transient simulation, the bed became fluidized for gas velocities greater or equal to 0.38 m s-1 staying in a pseudo-steady state. For the biomassgas system, the bed remained fixed only at the speed of 0.03 m s-1. Two systems were tested using the three components (gas, sand and biomass) differing from each other only by the size of sand and biomass particles. For high differences between these sizes, the system showed segregation during fluidization. In the system with lower size difference, the fluidization occurred more easily, since the segregation effects were attenuated. Volumetric fraction profiles of gas, sand and biomass were obtained for the 17 factorial design conditions used as well as a model that predicts the bed expansion in fluidized systems. The assay that showed higher final height of the bed (0.50 m) staying in a bubbling regime was one with 15% biomass particles with 375 mm in diameter and 85% of sand, being, therefore, a good condition to carry out fluidization.

Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T09:03:35Z (GMT). No. of bitstreams: 1 Silva_MarcioWagnerda_M.pdf: 1218438 bytes, checksum: eceeeda826d1358b20dfb5259a2bbf6f (MD5) Previous issue date: 2006 / Resumo: O processo de recobrimento de microgrânulos em Leito Fluidizado Pulsado-Rotativo (LFPR) foi investigado através da realização de experimentos de revestimento de celulose microcristalina (MICROCEL). Foi analisada e discutida a influência da carga de partículas, freqüência de pulsação da corrente gasosa, vazão de suspensão, pressão de atomização e temperatura de secagem sobre a eficiência de recobrimento, crescimento relativo em massa e índice de aglomerados. O principal objetivo do desenvolvimento do trabalho foi avaliar o desempenho e o comportamento do processo de recobrimento de microgrânulos em um equipamento de leito fluidizado com alimentação pulsada da corrente gasosa, frente a um equipamento de leito fluidizado convencional, cujo comportamento é amplamente descrito na literatura. Para a investigação do processo de recobrimento foi utilizada uma suspensão polimérica à base de Eudragitâ, e partículas de MICROCEL com diâmetro na faixa de 0,25 a 0,42 mm. O crescimento relativo médio das partículas foi de 3,63 %. Os experimentos foram realizados segundo técnicas de planejamento experimental, em que as análises dos resultados experimentais obtidos foram realizadas através da Metodologia da Superfície de Resposta. A análise dos efeitos das variáveis sobre as variáveis de resposta do processo foram utilizadas na construção de um modelo empírico, visando, quando possível, a predição do comportamento do processo. A análise dos modelos obtidos foi realizada através da análise de variância (ANOVA). As variáveis independentes analisadas foram: vazão de suspensão (Ws), pressão de atomização (Pat), temperatura do ar (Tar), carga de partículas no leito (M) e freqüência de pulsação (f). Todas a variáveis operacionais foram avaliadas em três diferentes níveis. Os resultados obtidos indicam que o leito fluidizado pulsado-rotativo é um equipamento adequado ao processo de recobrimento de microgrânulos, para as condições avaliadas, com grandes vantagens em relação ao equipamento de leito fluidizado convencional, destacando-se a redução na formação de aglomerados / Abstract: The coating process of microgranules in a Rotative-Pulsed Fluidized Bed was investigated through the accomplishment of microcrystalline cellulose (MICROCEL) coating experiments. The influence of particle load, gaseous stream pulsation frequency, suspension flow rate, pressure of atomization and drying temperature on the coating efficiency, relative growth and agglomeration index were analyzed and argued. The main objective of this work development was the evaluation of the performance and the behavior of microgranule coating process in fluidized bed equipment with beaten feeding of the gaseous stream, front a conventional fluidized bed equipment, which behavior is widely described in literature. For the inquiry of the coating process, a polymeric suspension of EudragitÒ and MICROCEL particles with diameter range of 0.25 ¿ 0.42 mm were used. The average relative growth of particles was of 3.63 %. The experiments were carried out according experimental planning techniques, where the obtained experimental results analyses had been carried through the Response Surface Methodology. The analysis of the effect of the independent variable on the process answer variables had been used in the construction of an empirical model, aiming to predict the process behavior, when possible. The analysis of the obtained models was carried out using the variance analysis (ANOVA). The independent variable used had been: suspension flow rate (Ws), atomization pressure (Pat), air temperature (Tar), bed particle load (m) and pulsation frequency (f). Results obtained shown that Rotative-Pulsed Fluidized Bed is an adequate equipment to be used in microgranules coating process in the evaluated operational conditions showing great advantages when compared to conventional fluidized bed, highlighting the agglomerate formation reduction / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Katia Tannous / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-22T22:57:33Z (GMT). No. of bitstreams: 1 Santos_EveraldoSilvinodos_M.pdf: 5165311 bytes, checksum: 94d8ad517b04e047990332460cb8259a (MD5) Previous issue date: 1997 / Resumo: Neste trabalho são considerados os fenômenos de mistura e segregação em leitos fluidizados de partículas polidispersas (quaternárias), pertencentes aos grupos A e B da classificação de Geldart. A coluna de fluidização utilizada possuía um diâmetro interno de 0,92m e uma altura de 2 m. Foi analisada a influência dos fatores operacionais, como a velocidade de excesso (U-U IND. E) e o tempo de fluidização, bem como de projeto, representada pela fração de área livre do distribuidor, e das características dos constituintes da mistura (diâmetro médio da mistura/concentração de imergíves) no grau de mistura axial do leito. Foram utilizadas quatro misturas que possibilitaram o estudo dos fenômenos de mistura e segregação, em leitos de partículas de mesma ou de diferentes massas específicas. Foi efetuado um mapeamento radial do leito. Os resultados para os perfis axiais mostram que o uso de uma velocidade suficiente para fluidizar todas as partículas e de um distribuidor de maior área livre favorece a mistura em um curto intervalo de tempo. O aumento da velocidade de excesso melhora a mistura nos leitos, principalmente pela maior quantidade de bolhas presentes. Uma maior fração de área livre do distribuidor favorece a homogeneização do leito, reduzindo as zonas mortas próximo ao distribuidor. O aumento da concentração das partículas imergíveis desfavorece o processo de mistura. O mapeamento radial confirma que para a velocidade de fluidização completa as partículas estão bem misturadas / Abstract: In this work the mixing and segregation phenomena of polydisperse particles (quaternaries) belonging to the A and B Geldart' s groups are investigated. The fluidization column have been constructed with a internal diameter of 0.92 m and height of 2 m. The influence of operating factors in the degree axial mixing of the bed, like excess velocity (U-'U IND. E¿) and fluidization time, as well as design, like distributor free area, and of the characteristcs of the constituents of mixture (mean diameter of mixture/jetsam concentration) were analised. Four mixtures that allowed the study of the phenomena of mixing and segregation in beds of same or different densities were used. A radial mapping of the bed was performed. The axial profile results show that the use of a velocity high enough for complete fluidization and the use of a distributor with large free area promote the mixing in a small time interval. The increment of excess velocity improves the mixing in the beds, mainly by larger quantity of bubbles. A larger free area improves the bed homogenezation, reducing the dead zones near the distributor. The increment ofjetsam concentration hampers the mixing process. The radial mapping confirm that for the velocity of complete fluidization the particles are well mixed. / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientadores: Sandra Cristina dos Santos Rocha, Virginia Aparecida da Silva Moris / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-13T14:24:52Z (GMT). No. of bitstreams: 1 Costa_SuzaraSantos_M.pdf: 3149435 bytes, checksum: 4253d824e6807a4d4dabe9f5337e4982 (MD5) Previous issue date: 2009 / Resumo: O leito vibrofluidizado (LVF) consiste na aplicação de vibração mecânica ao leito fluidizado convencional com o objetivo de reduzir a ocorrência de bolhas, canais preferenciais e evitar o fenômeno da de fluidização em processos como recobrimento, granulação, entre outros. A utilização do LVF é diversificada para materiais coesivos, adesivos, aglomerados e pastosos. A granulação consiste no aumento da partícula mediante a incorporação de materiais ativos e/ou inertes e é um importante processo utilizado com o objetivo de melhorar aspecto, manuseio, compactação e transporte de partículas finas. Esse processo é bastante encontrado na literatura com o uso em leitos fluidizados convencionais, contudo, o processamento de materiais que possuem forças interpartículas intensas quando sujeitos a aspersão de ligantes, torna-se difícil e dispendioso. A celulose microcristalina é originada da hidrólise ácida da celulose e utilizada, entre outros usos industriais, como estabilizante e aditivo alimentício. Na indústria farmacêutica, é um dos excipientes mais utilizados em formulações de dosagem oral. Baseado no exposto foi realizado um estudo sobre a granulação da celulose microcristalina em leito vibrofluidizado, utilizando como ligante solução de matodextrina 35%. A solução foi aspergida sobre o leito de partículas através de um sistema de atomização acoplado ao leito vibrofluidizado. Foi desenvolvido um planejamento experimental fatorial fracionário (25-1), cujas variáveis operacionais foram: amplitude (A) e frequência (f) de vibração, pressão de atomização (P), temperatura do ar de entrada (T) e vazão de solução (Q). Os níveis das variáveis de entrada no planejamento foram: 0,01m e 0,02m; 3 Hz e 6 Hz, 5 Psig e 15 Psig, 60ºC e 80ºC e 4 ml/min e 10 ml/min, respectivamente. O planejamento foi desenvolvido com 4 repetições no ponto central. Para avaliar a qualidade do produto foram analisadas três variáveis de resposta, que resultaram nas seguintes faixas: crescimento da partícula - 3,17% a 33,11%, ângulo de repouso - 8,4º a 12º e índice de aglomerados - 0,2% a 5,69%. Com o experimento estatisticamente planejado constatou-se que todas as variáveis independentes influenciaram as variáveis de resposta consideradas e, portanto, não foi possível estabelecer um planejamento completo com um número menor de variáveis. O comportamento fluidodinâmico da celulose microcristalina antes da granulação também foi estudado. As curvas obtidas refletiram um comportamento característico encontrado na literatura de leitos vibrofluidizados. A fluidodinâmica do material permitiu, embora com dificuldade, determinar a velocidade de mínima fluidização (pelo método convencional da interseção das retas em leitos fluidizados) e velocidade de mínima fluidização completa para leitos vibrofluidizados. A velocidade de mínima mistura do material também foi determinada, mas por observação visual durante os experimentos. A velocidade de operação foi estabelecida em 0,30 m/s após os ensaios preliminares de fluidodinâmica e de granulação. O produto final obtido após o processo de granulação apresentou boa escoabilidade e um aumento no seu diâmetro médio de Sauter, confirmando a granulação da celulose microcristalina e revelando o leito vibrofluidizado como equipamento promissor para efetuar o processo de granulação. / Abstract: The vibrofluidized bed (VFB) consists in applying mechanical vibration to the conventional fluidized bed to reduce the occurrence of bubbles, preferential channeling and defluidization phenomena, which are common when fluidizing cohesive, adhesive and paste materials. Granulation is used to increase particle size through incorporation of active materials and/or inert and it is a very important process to improve the appearance, handling and transport of fine particles. Granulation is usually conducted using conventional fluidized beds; however, the processing of powders having high interparticle forces, when subjected to intense spraying of binders, is difficult and expensive. Microcrystalline cellulose is a fine powder that is originated from acid hydrolysis of cellulose and is used, among other industrial uses, as a stabilizer, food additive and carrier in drugs. This work reports the analysis of wet granulation of microcrystalline cellulose in a vibrofluidized bed using an aqueous maltodextrina solution as binder. A factorial experimental design (25-1) was developed with the independent variables: vibration amplitude (A) and frequency (f), atomization pressure (P), inlet air temperature (T) and maltodextrin solution flow rate (Q). The responses analyzed were in the following levels: particle growth - 3.17% to 33.11%, angle of repose - 8.4º to 12º and percentage of lumps - 0.2% to 5.69%. The statistical analysis of the experimental design was able to determine that all the independent variables showed significant influence on the process and so it was not possible to perform an experimental design with a smaller number of variables. The fluid dynamics of the bed of microcrystalline cellulose before granulation was also analyzed and it presented the behavior of fluid dynamic curves of vibrofluidized beds found in the literature. In spite of the difficulty, the fluid dynamic curves allowed to determine the minimum fluidization velocity (conventional method of intersection of straight lines of fixed and fluidized regions) and complete minimum fluidization for vibrofluidized beds. The velocity of minimum mixture was also determined, by visual observation. The operation velocity was set at 0.30 m/s based on the dynamic tests and preliminary tests of granulation. The final product showed excellent flowability and generated an increase in its mean Sauter diameter, thus confirming the granulation of microcrystalline cellulose and showing the vibrofluidized bed as promising equipment for this process. / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientadores: Sandra Cristina dos Santos Rocha, Virgínia Aparecida da Silva Moris / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T07:32:21Z (GMT). No. of bitstreams: 1 Nunes_JanainaFerreira_D.pdf: 1733397 bytes, checksum: cf94e9d446e8a6b5e90066cbd82e3c19 (MD5) Previous issue date: 2012 / Resumo: O equipamento mais apropriado e utilizado no recobrimento de partículas finas é o leito fluidizado. Entretanto, trabalhos de pesquisa e a prática industrial mostram que, para alguns processos, são necessárias modificações do equipamento convencional para melhorar o regime fluidodinâmico. O emprego de vibração mecânica ao leito fluidizado convencional tem resultado em significativa melhora no desempenho de processos com partículas finas e coesivas, de difícil fluidização. A aplicação de recobrimento em partículas desse tipo (principalmente químicos, fármacos e alimentos) tem adquirido cada vez mais importância industrial, tendo diversas finalidades, como por exemplo, a diminuição da reatividade do material recoberto com o meio externo (luz, oxigênio e água, entre outros agentes). Levando em conta a importância do recobrimento de grânulos finos, a dificuldade de operação dos leitos fluidizados convencionais com esse tipo de partícula e a escassez de estudos deste processo no leito vibrofluidizado, o objetivo deste trabalho foi realizar um estudo da fluidodinâmica e do processo de proteção do bicarbonato de sódio em um leito vibrofluidizado por recobrimento e aglomeração. As seguintes etapas foram executadas: caracterização física do bicarbonato de sódio, estudo da fluidodinâmica em leito fluidizado convencional e vibrofluidizado, análise dos processos de recobrimento e aglomeração por suspensão polimérica em função da amplitude e freqüência de vibração e da temperatura do ar, avaliando o diâmetro médio, índice de Hausner, ângulo de repouso, índice de escoabilidade e liberação de CO2 do produto, além do índice de torrões e massa elutriada no processo. Foram também realizadas análises da eficiência de proteção do produto para diferentes condições de temperatura e umidade relativa do ambiente e do monitoramento do processo utilizando medidas de flutuação de pressão. A fluidodinâmica do material no leito vibrofluidizado resultou em curvas características típicas da literatura e foram determinadas as velocidades de mínima fluidização, vibrofluidização e vibrofluidização completa e de mínima mistura, variando-se a amplitude entre 0 e 2 cm e a freqüência entre 0 e 360 rpm. Foram observadas menores velocidades de fluidização incipiente para o leito vibrofluidizado em relação ao leito fluidizado convencional, além de expressiva melhora na dinâmica em leito vibrofluidizado. O processo de recobrimento foi realizado variando-se a amplitude entre 0 e 2 cm, a freqüência entre 0 e 360 rpm e a temperatura do ar de fluidização entre 60° C e 80° C. Os resultados revelaram a presença de dois mecanismos distintos dependente das condições de operação: recobrimento das partículas individuais por camadas e aglomeração por nucleação, que tiveram como conseqüência uma faixa bastante ampla de crescimento (6,69 % a 44,50 %). O índice de escoabilidade, ângulo de repouso e índice de Hausner foram menores para partículas recobertas comparadas com o bicarbonato de sódio sem recobrimento, indicando melhor fluidez do material após o processo. Foi comprovada a eficiência da proteção do bicarbonato de sódio tanto pelo recobrimento como pela aglomeração, visto que para o bicarbonato processado a perda de CO2 ficou entre 2 % e 9 %, enquanto para o bicarbonato puro essa perda variou entre 5,5 % e 12,5 % nas condições de ambiente estudadas. A análise das isotermas de adsorção confirmou a eficiência de proteção por recobrimento e aglomeração do bicarbonato de sódio, e o modelo de GAB mostrou-se adequado para o ajuste das isotermas de adsorção do bicarbonato de sódio recoberto e aglomerado. Foi também verificada a viabilidade do monitoramento do processo através de medidas de flutuação de pressão em tempo real / Abstract: The most appropriate equipment used in the coating of fine particle is the fluidized bed. However, research studies and industrial practice show that in some cases modifications of the conventional equipment is necessary to maintain its dynamic stability. The use of mechanical vibration in conventional fluidized beds results in significant improvement of the process performance with fine and cohesive particles, which are difficult to fluidize. The coating of fine particles (mainly chemicals, pharmaceuticals and food) is getting more and more industrial importance aiming at different purposes, as for example to decrease reactivity of the material with the environment (light, oxygen and water, among others). Due to the importance of coating of fine particles and the rareness of studies on this process in vibrofluidized beds, this work aims to study the fluid dynamics and coating of sodium bicarbonate in a vibrofluidized bed, passing through the following stages: the sodium bicarbonate physical characterization, fluid dynamic analysis of the material in conventional and vibrofluidized beds, process analysis as a function of amplitude and frequency of vibration, and of the fluidizing air temperature, evaluating the product mean diameter, Hausner index, angle of repose, flowability index and CO2 release, as well as lump index and elutriated mass. Product protection efficiency and analysis of process monitoring using measurements of pressure fluctuation were also carried out. The material fluid dynamics provided characteristic curves typical of the ones found in the literature for vibrofluidized beds. Minimum fluidization, minimum vibrofluidization, minimum complete vibrofluidization and minimum mixture velocities were determined for varying vibration amplitude between 0 and 2 cm and frequency between 0 and 360 rpm. Inferior values were obtained for the vibrofluidized bed incipient velocity, compared to the conventional fluidized bed, and intense movement of the particles with enhancement of the bed dynamics was verified. The coating process was performed for varying vibration amplitude between 0 and 2 cm, frequency between 0 and 360 rpm and temperature of fluidizing air between 60 °C and 80 °C. The results revealed the presence of two distinct mechanisms depending on the operating conditions: layering of individual particles and agglomeration by nucleation, having as a consequence a broad range of particle growth (6.69 % to 44.50 %). The flowability index, angle of repose and Hausner index of the coated particles were smaller compared with uncoated sodium bicarbonate, indicating greater fluidity of the material after processing. The efficiency of protection of sodium bicarbonate by the polymeric coating/agglomeration was demonstrated as CO2 loss was between 2 % and 9 % for processed bicarbonate, while that for the pure bicarbonate ranged between 5.5 % and 12.5 % for the environment conditions analyzed. The analysis of adsorption isotherms confirmed the sodium bicarbonate protection by polymeric coating and agglomeration, and the GAB model was suitable for adjusting the adsorption isotherms of coated and agglomerated sodium bicarbonate. Also, the viability of monitoring the process through on line measures of pressure fluctuation was verified / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

Orientador: Sandra Cristina dos Santos Rocha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T05:32:13Z (GMT). No. of bitstreams: 1 Cunha_RobertoLuisGomesda_M.pdf: 4555527 bytes, checksum: c05f06e6d6afae91414137377cbe242d (MD5) Previous issue date: 2004 / Resumo: O recobrimento de materiais granulares é urna operação bastante utilizada pela industria Farmacêutica com diversas finalidades, que vão desde fatores estéticos ao controle da taxa de dissolução de substâncias químicas e incluem: facilitar a administração através da obtenção de uma super:ficie lisa, identificar o medicamento pelo emprego de cores, proteger a droga de agentes atmosféricos como, luz, oxigênio, entre outros. Neste trabalho estudou-se a fluido dinâmica e o recobrimento da celulose microcristalina - MICROCEL, que é o principal excipiente usado na indústria farmacêutica, com uma suspensão aquosa a base de Eudragit'1! / Abstract: The coating of granular materials is an operation widely used by tbe Pharrnaceutical industry with diverse purposes: to improve the product appearance, to obtain a product with controlled release of active components, to facilitate the administration through the artainrnent of a smooth surface, to identii)r the drug by colors, to prateet the drug ITom atmospheric agents as, light, oxygen, among others. ln this work, the fluid dy11aID.ics and the coating of microcrystalline cellulose - MICROCEL, which is the main excipient used in the pharmaceutical industry, was analyzed. An aqueous polymeric suspension of Eudragit@ was used as the coating liquid in a fluidized bed. The suspension was eontinuously sprayed on the granules by a double-fluid nome loeated at the top ofthe bed. The objeetive of this work was to analyze the fluid-dynamics of a fluidized bed during the coating process, using particles of type B according to Geldart classification, aiming at the identillcation of the bed saturation (instability andíor fluidized regime collapse) and relating it to the operating conditions. The independent variables analyzed were the flow rate of eoating suspension (Ws), for the values: 6.4, 11.0 and 18.0 glmin and the atomization pressure (pat) in the following levels: 10, 15 and 20 psig. The inlet aÍ! temperature of the bed was kept constant at 70°C, as well as the sÍZe of the particles, in the range of 0.30 - 0.42 mIn. A 32 factorial desígn was employed to evaluate the influences of the operating condítions on the responses: the process efficíeney, the partíc1es growth, the agglomerate formation and the instantaneous saturation until the bed collapse. The process efficiency varied ITom 51 to 99,7 %, the particles growth was characteristíc of a fi1m coating, the agglomerates índex varied ITom 0.38 to 6.28 % and the bed instantaneous saturation ITom 5.370.10-3 to 16.828.10-3 (min-l). During the experiments, i1 was observed that the fluidized regime collapse is related to the bed saturation, since the bed porosity decreases with the saturation increase, with consequent packing of the particles and collapse ofthe bed regime / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Electrostatic charge generation is unavoidable in gas-solid fluidized beds due to the repeated particle-particle and particle reactor wall contacts and separations. In industrial operations such as in polyethylene production this phenomenon results in the significant problem of reactor wall fouling, known as “sheeting”. To better understand the underlying charging mechanisms involved in gas-solid fluidized beds in an attempt to eliminate and/or reduce the effect a novel on-line electrostatic charge measurement technique was developed, which concurrently provided information on both the degree of fluidized bed electrification and reactor wall fouling. A Faraday cup replaced the windbox of the fluidized bed while another cup was placed at the top of the column. The distributor plate was uniquely designed for the systematic removal of bed particles and those adhered to the column wall for their charge measurement with the bottom Faraday cup, and the charge of the entrained particles was measured by the top Faraday cup. This is the first study which allowed the charge measurement of particles in the bulk of the bed, particles adhered to the column wall, and those entrained, simultaneously. In addition, this method uniquely permitted the evaluations of the degree of reactor wall fouling under different operating conditions. An experimental program was designed to investigate the influence of bed hydrodynamics (fluidizing gas velocity and particle size), fluidization column wall material, and the addition of different solid additives. Fluidizing particles were polyethylene resin from an industrial reactor. Bi-polar charging was observed where the elutriated particles were oppositely charged compared to those in the bulk of the bed and those adhered to the column wall. Particles within the wall coating were also found to be bi-polarly charged. With the resin tested as received, a certain sized particles (350-575 µm) adhered to the column wall. The specific charge of the particles near the column wall was found not to be a definite indication of the amount of wall fouling. Increasing the gas velocity promoted wall fouling and elevated the charge density of the particles within both bubbling and slugging flow regimes. The effect of solid additive injection was examined with two static drivers known to reduce wall fouling in industrial operations, a deactivated catalyst, and the catalyst support. It was found that the catalyst promoted, while one of the static drivers reduced wall fouling.

Commercial ebullated bed hydroprocessors, such as the LC-Finer, are used for the production of synthetic crude oil by upgrading bitumen extracted from the Alberta oil sands. The objective of this thesis was to investigate the impact of an increased vacuum distillation tower bottoms feed fraction on the reactor fluid dynamics (e.g., bed and freeboard phase holdups, bubble characteristics and local fluidization behaviour). Industrial conditions were simulated in a high pressure gas-liquid-solid fluidization system based on dimensional and geometric similitude. Considering important geometric characteristics and matching dimensionless groups, base-case conditions resulted in an ebullated bed of nitrogen, 0.5 wt.% aqueous ethanol, and aluminum cylinders (average lengths and diameters of 7.5 and 3.2 mm, respectively) operating at 6.5 MPa and a gas-to-liquid superficial velocity ratio of 0.78. The proposed scale-down method resulted in high gas holdup conditions similar to industrial measurements. The use of the Sauter mean diameter to account for particle size and shape at the simulation conditions was investigated by comparing glass spheres with diameters of 4 and 1.5 mm to aluminum cylinders with equivalent volume-to-surface area ratios. Local bubble characteristics, including gas holdups, bubble rise velocities, and chord lengths, were then investigated under various operating conditions using a monofibre optical probe. Overall fluid dynamics were studied when increasing the liquid viscosity and varying the gas and liquid superficial velocities due to their relevance for industrial ebullated bed hydroprocessors. Freeboard and bed region gas holdup relations were studied and correlations were developed for gas and solid holdups at the simulation conditions based on the dimensionless groups. Mesophase generation in hydroprocessors due to undesired secondary reactions was also considered for an increased vacuum residue feed fraction. Adding a dispersed immiscible liquid phase which preferentially wetted the particles was therefore experimentally studied at non-simulating conditions using nitrogen, biodiesel, glycerol and various particles, where fluidization behaviour and phase holdups were considerably affected due to particle clustering. A study on the impacts of particle size, shape and material demonstrated the influences of fluid and particle properties, specifically the relative surface energies and viscous forces, on agglomeration due to interparticle liquid bridging.

This thesis discusses the results and insights gained from developing a CFD model of a pilot-scale pressurized dry coal-feed system using the Barracuda CFD software and modeling various design concepts and operating conditions. The feed system was required to transport approximately 0.00378 kg/s (30 lb/hr) of pulverized coal from a vertical hopper to a 2.07 MPa (20.4 atm or 300 psi) reactor with a CO2-to-coal mass flow ratio of 1-2. Two feed system concepts were developed and tested for coal mass flow, CO2-to-coal mass ratio, steadiness, and uniformity. Piping system components also were evaluated for pressure drop and coal roping.With the first system concept, Barracuda software model parameters were explored to observe their effect on gas and particle flow. A mesh sensitivity study revealed there exists too fine of a mesh for dual-phase flow with Barracuda due to the particle initialization process. A relatively coarse mesh was found to be acceptable since the results did not change with increasing mesh refinement. Barracuda sub-model parameters that control particle interaction were investigated. Other than the close pack volume fraction, coal flow results were insensitive to changes in these parameters. Default Barracuda parameters were used for design simulations.The gravity-fed system (first concept) relied on gravity to transfer coal from a hopper into the CO2 carrier gas. This design was unable to deliver the required coal mass flow rate due to the cohesion and packing of the particles being greater than the gravity forces acting on the particles. The fluidized bed (second concept) relied on CO2 flow injected at the bottom of the hopper to fluidize the particles and transport them through a horizontal exit pipe. Additional CO2 was added post-hopper to dilute the flow and increase the velocity to minimize particle layout. This concept was shown to decouple the fluidized particle flow and dilution CO2 flow, providing significant design and operating flexibility. A non-uniform mesh was implemented to maintain a high mesh refinement in the 0.635-cm (¼-in) diameter transport pipe with less refinement in the hopper/bed region. The two main hopper diameters evaluated measured 5.08-cm (2-in) and 15.24-cm (6-in). Successful designs were achieved for each with appropriate coal mass flow rates and CO2-to-coal ratios. The particle flow was sufficiently steady for use with a coal burner.A piping system study was performed to test pneumatic transport and the effects of pipe length and bend radius. For a 1-to-1 gas-to-particle mass flow, particle layout occurred after 30 cm of travel. Particle roping occurred to various extents depending on the pipe bend radius. Bend radii of 0.318, 60.96, and 182.88 centimeters were simulated. Roping increased with bend radius and high pressure. Greater gas flow rates increased particle flow steadiness and uniformity. A simple methodology was identified to estimate the pressure drop for different piping system configurations based on the piping components simulated.