Dissertations / Theses on the topic 'Fluidised bed drying'

Drying is a major contributor to total energy consumption in manufacturing processes. As fluidised bed technology is a common method of particle drying, improvements in efficiencies are widely desirable. Low frequency flow pulsation has been found in the literature to reduce gas pumping requirements in fluidised beds and increase drying rates. However, research to date has used pulsation frequency range that tends to be within a 1-15 Hz limit. Consequently, a high pulsation frequency range of 200-300 Hz was applied to a selection of fluidised bed indicators to determine if a high frequency flow pulsation altered fluidisation when compared to a continuous flow regime. This is the first study to investigate the effects of high frequency flow pulsation of fluidised bed dynamics and drying. The effect of high frequency flow pulsation was studied at three scales: single particle level, 2-dimensional lab scale fluidised bed, and a 3-dimensional fluidised bed. Experiments were designed to directly compare pulsed and continuous flow. The high frequency flow pulsation was achieved using a type of fluidic oscillator. This used no additional energy input to pulse the gas flow. A range of pulsation frequencies and amplitudes were achieved through altering the length of a feedback tube on the oscillator and increasing or decreasing the gas flow rate. It was found that the oscillator operated through both the conventional double outlet mode, but also through a single outlet when one was closed off. This allowed for a comparison between both regimes, with the single outlet mode creating a preferable gas flow distribution. The high frequency pulsed flow regime was found to produce a higher pressure drop over the 3D bed distributor plate than the continuous flow regime. On a single particle level, large Group D single particles were studied through a drying curve whilst suspended in a static crucible in the gas flow or fluidised within a tube. These experiments showed that, in some particles, the pulsed flow regime inhibited or enhanced drying. It also demonstrated that a fluidised single particle has a greater variation in movement under a pulsed flow regime. In the 2D fluidised bed, bubbles were observed to be larger and more populous in a Group A powder under the pulsed flow regime compared to the continuous flow regime. Bed expansion was found to be greater under the pulsed flow regime in the 3D bed. Many of the observed differences between pulsed and continuous flow were small, making it difficult to form firm scientific conclusions. However, these results suggest that the addition of a high frequency flow pulsation to a fluidised bed dryer may change the fluidisation regime and characteristics. Whilst low frequency flow pulsation creates a physical interaction between the gas flow pulse cycles and particle displacement or bubble formation, high frequency flow pulsation is shown by this study to potentially influence fluidised bed indicators through gas vibration or boundary layer alteration.

The aim of this research was the development of an accurate, robust and reliable electrical capacitance tomography (ECT) sensor for the online measurement of solids concentration and moisture content profiles of fluidised bed dryers. In the pharmaceutical industry, fluidised bed dryers are used to dry wet particles prior to compression. Although electrical capacitance tomography (ECT) has been traditionally used to obtain images of the fluidisation processes, in this research, capacitance measurements from an ECT sensor mounted on a lab-scale fluidised bed dryer were used to estimate solids concentration and moisture content profiles. The effects of the process parameters, such as particle size, gas velocity, inlet gas temperature and relative humidity, on the moisture content of solids in the batch fluidlsed bed have been analysed theoretically.

A mathematical model for the drying of particulate solids in a continuous vibrated fluidised bed dryer was developed and applied to the drying of grain wetted with a single liquid and porous particles containing multicomponent liquid mixtures. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was regarded; thus, only the longitudinal changes of particle moisture content and composition as well as temperature along the dryer were considered. Concerning the material model, mass and heat transfer in a single isolated particle was studied. For grain wetted with a single liquid, mass and heat transfer within the particles was described by effective transfer coefficients. Assuming a constant effective mass transport coefficient and effective thermal conductivity of the wet particles, analytical solutions of the mass and energy balances were obtained. The variation of both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with non-uniform inlet conditions and averaged coefficients from previous locations in the dryer. Calculation results were verified by comparison with experimental data from the literature. There was fairly good agreement between experimental data and simulation but the results depend strongly on the correlation used to calculate heat and mass transfer coefficients.   For the case of particles containing a multicomponent liquid mixture dried in the vibrated fluidised bed dryer, interactive diffusion and heat conduction were considered the main mechanisms for mass and heat transfer within the particles. Assuming a constant matrix of effective multicomponent diffusion coefficients and thermal conductivity of the wet particles, analytical solutions of the diffusion and conduction equations were obtained. The equations for mass transfer were decoupled by a similarity transformation and solved simultaneously with conduction equation by the variable separation method. Simulations gave a good insight into the selectivity of the drying process and can be used to find conditions to improve aroma retention during drying.   Also, analytical solutions of the diffusion and conduction equations applied to liquid-side-controlled convective drying of a multicomponent liquid film were developed. Assuming constant physical properties of the liquid, the equations describing interactive mass transfer are decoupled by a similarity transformation and solved simultaneously with conduction equation and the ordinary differential equation that describes the changes in the liquid film thickness. Variations of physical properties along the process trajectory were taken into account as in the previous cases. Simulation results were compared with experimental data from the literature and a fairly good agreement was obtained. Simulations performed with ternary liquid mixtures containing only volatile components and ternary mixtures containing components of negligible volatility showed that it is difficult to obtain an evaporation process that is completely controlled by the liquid-side mass transfer. This occurs irrespective of the initial drying conditions.   Despite simplifications, the analytical solution of the material model gives a good insight into the selectivity of the drying process and is computationally fast. The solution can be a useful tool for process exploration and optimisation. It can also be used to accelerate convergence and reduce tedious and time-consuming calculations when more rigorous models are solved numerically.
QC 20110614

Cette étude est consacrée à l'élaboration de vernis d'enrobage composites constitués d'une fine dispersion de matériau hydrophobe dans une matrice de polymère. Ce type de matériau est appliqué à la surface de particules alimentaires, grâce à un procédé de pulvérisation en lit fluidisé, afin d'assurer la protection de ces particules vis-à-vis d'atmosphères humides. Nous avons développé un protocole de formulation, des vernis d'enrobage et des outils de caractérisation des dispersions liquides mais également des vernis secs sous forme de films minces. Nous avons étudié l'influence des paramètres liés au protocole de formulation et à la composition sur la stabilité de la dispersion, sur les propriétés d'usage des films d'enrobage secs mais également sur les interactions entre les différents constituants. A partir de l'ensemble de ces résultats, deux formulations ont été retenues. Afin d'étudier l'influence des conditions séchage sur les propriétés des films d'enrobage, nous avons conçu une veine de séchage convectif. Les résultats ont montré que la morphologie et les propriétés des films secs sont essentiellement pilotées par la période de séchage à vitesse décroissante, lorsque la cinétique d'évaporation du solvant est limitée par la diffusion de celui-ci à travers le film de vernis. De plus, nous avons observé que l'augmentation de la température de séchage, notamment pour des températures de séchage proche de la température de fusion des composés fusibles des vernis (40°C pour le PEG 1500 et 55°C pour l'acide stéarique), induit des transformations morphologiques importantes des films. L'apparition de cette nouvelle morphologie provoque une amélioration notable des possibilités de déformation des films secs sans modifier leurs propriétés barrières.

This study is aimed to compare the fluidized bed and microwave drying with microwave assisted fluidized bed drying. For this purpose, macaroni beads (2.4±
0.08 mm diameter) were dried from about 20% to 12% moisture content in a fluidized bed of 7.6 cm diameter, in a domestic microwave oven with a power of 609 W and in the fluidized bed placed in the microwave oven conditions. In the experiments with the fluidized bed three air temperatures
50, 60 and 70°
C at an air velocity of 2.3 m/s and in those with the microwave oven two power levels
50% and 100% were used. The drying curves indicated that the drying rate increased with the air temperature and microwave power in each drying method. Microwave assisted fluidized bed drying reduced the drying time by about 50% and 11% on the average compared with the fluidized bed and microwave drying, respectively. Therefore, it was concluded that the drying time was reduced more by the effect of microwave energy than the fluidization. The effective diffusivities in the fluidized bed and microwave assisted fluidized bed drying were found to be in the order of 4.125x10-11 and 8.772x10-11 m2/s on the average, respectively. The effective diffusivities for the fluidized bed drying were fitted to an Arrhenius type of equation and the magnitude of the activation energy was found to be in the order of 12595 kJ/kg mol.

Пояснювальна записка до дипломного проекту «Удосконалення роботи сушарки киплячого шару у виробництві таблетованого ампіциліну» містить 92 сторінок, 39 літературних джерел, 21 рисунків, 23 таблиць. В магістерській дисертації розглянуто сушарку з псевдозрідженим шаром та удосконалену частину апарату решітку сушарки псевдозрідженого шару. Решітка сушарки псевдозрідженого шару належить до галузі сушильних апаратів, які застосовують у лініях виробництва харчових продуктів та фармацевтичній галузі. Виробництво твердих лікарських засобів (ЛЗ) є найбільш поширеною і відомою технологією у фармації, в якій на першому місці за кількістю продукції знаходяться таблетки. Базовою вимогою до готової продукції будь-якого виробництва ЛЗ є забезпечення якості, безпечності та ефективності. Забезпечення цієї вимоги обумовлюється використанням обладнання з високою функціональною відповідністю чинній технології виробництва. Пропонована решітка сушарки псевдозрідженого шару забезпечує якісне висушування матеріалу та підвищує ефективність роботи даної сушарки. Для підтвердження працездатності та надійності конструкції були проведені тепловий, гідравлічний, конструктивний і міцнісний розрахунки елементів конструкції. Проведений патентний пошук, за рахунок чого, виконаний порівняльний аналіз основних показників конструкції сушарки з діючими аналогами. Також у проекті розглянуті питання з монтажу та експлуатації теплообмінника. Розрахунки та креслення виконані згідно чинних стандартів, з використанням сучасних системних та інформаційних технологій.
Explanatory note to the diploma project "Improvement of the fluidized bed dryer in the production of ampicillin tablets" contains 92 pages, 39 references, 21 figures, 23 tables. In the master's dissertation the dryer with a fluidized bed and the improved part of the apparatus of the lattice of the dryer of the fluidized bed are considered. The lattice of the fluidized bed dryer belongs to the field of dryers used in food production lines and the pharmaceutical industry. The production of solid drugs (DR) is the most common and well-known technology in pharmacy, in which the first place in terms of the number of products are tablets. The basic requirement for finished products of any drug production is to ensure quality, safety and efficiency. Ensuring this requirement is due to the use of equipment with high functional compliance with current production technology. The proposed lattice of the fluidized bed dryer provides high-quality drying of the material and increases the efficiency of this dryer. To confirm the efficiency and reliability of the structure, thermal, hydraulic, structural and strength calculations of structural elements were performed. A patent search was carried out, due to which a comparative analysis of the main indicators of the dryer design with the current analogues was performed. The project also addresses issues related to the installation and operation of the heat exchanger. Calculations and drawings are made according to current standards, using modem system and information technologies.

Пояснювальна записка до дипломного проекту «Модернізація решітки сушарки псевдозрідженого шару для дослідження процесу псевдозрідження» містить 96 сторінок, 37 літературних джерел, 23 рисунків, 21 таблиць. В магістерській дисертації розглянуто сушарку з псевдозрідженим шаром та удосконалену частину апарату решітку сушарки псевдозрідженого шару. Решітка сушарки псевдозрідженого шару належить до галузі сушильних апаратів, які застосовують у лініях виробництва харчових продуктів та фармацевтичній галузі. Новим є те, що, решітка через яку проходить повітря має похилі отвори, які розташовані по спіралі Архімеда для створення вихрових потоків під час висушування матеріалу. Пропонована решітка сушарки псевдозрідженого шару забезпечує якісне висушування матеріалу та підвищує ефективність роботи даної сушарки. Для підтвердження працездатності та надійності конструкції були проведені тепловий, гідравлічний, конструктивний і міцнісний розрахунки елементів конструкції, було здійснено комп’ютерний аналіз та необхідні розрахунки в програмі «Ansys» для перевірки працездатності апарату. Проведений патентний пошук, за рахунок чого, виконаний порівняльний аналіз основних показників конструкції сушарки з діючими аналогами. Також у проекті розглянуті питання з монтажу та експлуатації теплообмінника. Розрахунки та креслення виконані згідно чинних стандартів, з використанням сучасних системних та інформаційних технологій.
The explanatory note to the diploma project "Modernization of the fluidized bed dryer grid for the study of fluidization process" contains 96 pages, 37 literary sources, 23 drawings, 21 tables. The master's thesis deals with the fluidized bed dryer and the improved part of the apparatus of the fluidized bed dryer grid. The fluidized bed dryer grate belongs to the field of drying apparatus used in food production lines and the pharmaceutical industry. What is new is that the grate through which the air passes has sloping openings, which are arranged in an Archimedes spiral to create vortex flows during material drying. The proposed fluidized bed dryer grille provides high-quality drying of the material and increases the efficiency of the dryer. Thermal, hydraulic, structural and durable calculations of structural elements were carried out to confirm the construction's reliability and reliability, computer analysis and the necessary «Ansys» calculations were performed to verify the machine's performance. A patent search was carried out, whereby a comparative analysis of the main parameters of the design of the dryer with its existing analogues was performed. The project also addresses the issues of installation and operation of the heat exchanger. Calculations and drawings are made according to current standards, using modem system and information technologies.

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Neste trabalho estudou-se inicialmente a secagem de fatias de goiabas cortadas no sentido polar da fruta, os resultados obtidos mostraram que o produto apresentou alterações desfavoráveis a comercialização, apresentando alteração significativa na cor, escurecimento, como também, na textura das fatias. Numa segunda etapa utilizou-se os processos combinados de leito fixo/leito de jorro e de leito fixo/leito fluidizado para a secagem de pedaços cúbicos de goiaba obtidos do mesocarpo da fruta. Inicialmente, fez-se um estudo fluidodinâmico dos pedaços cúbicos de goiaba em leito de jorro e leito fluidizado o qual mostrou a viabilidade do uso dessas técnicas, embora as propriedades físicas do material após pré-secagem em leito fixo tenham afetado sensivelmente a fluidodinâmica dos leitos, os quais sofreram modificações estruturais. No estudo fluidodinâmico em leito de jorro foram determinadas a velocidade mínima de jorro e a altura máxima capaz de manter o jorro estável. Os resultados obtidos experimentalmente foram comparados com correlações da literatura e mostraram boa concordância. Em leito fluidizado determinou-se a velocidade de mínima fluidização experimental os resultados obtidos apresentaram boa com os determinados através de correlações empíricas. Posteriormente, realizou-se um estudo das propriedades físicas, propriedades térmicas e um estudo do equilíbrio higroscópico dos pedaços cúbicos da fruta. Os resultados encontrados da massa específica e do diâmetro mostraram que estes se enquadram na categoria D, segundo a classificação de Geldart, o que favorece a um jorro e fluidização incipiente. Em relação ao estudo do encolhimento dos cubos observou-se um comportamento linear com o volume par todos os níveis de umidade do produto durante a secagem. Contudo, para umidade de 1,5 em base seca, durante a secagem em leito de jorro, duas regiões bem distintas foram caracterizadas pela mudança na inclinação da curva. Em relação às propriedades térmicas estas apresentaram a mesma tendência, ou seja, aumentando com a elevação da umidade passando por um máximo correspondente ao máximo encontrado na massa específica. No estudo do equilíbrio higroscópico, observou-se que as isotermas, dentro da faixa de temperatura estudada, foram ajustadas ao modelo de Henderson apresentando um ajuste satisfatório, não se observando efeito da temperatura. No estudo da cinética de secagem utilizou-se o modelo difusional para esferas, truncado em quatro termos levando-se em conta o efeito do encolhimento, os resultados obtidos para leito fixo/leito de jorro ajustou bem os dados experimentais. Por outro lado, este modelo não prediz satisfatoriamente o comportamento da secagem em leito fixo/leito fluidizado haja vista o fator encolhimento não ter sido utilizado no modelo. O coeficiente de difusão efetivo para níveis de umidades mais elevados apresentaram a mesma ordem de grandeza para ambos os processos independente da altura do leito. A hipótese de controle difusional externo desprezível foi confirmada a partir do número de Biot de massa que foi muito elevado. O desempenho dos secadores foi realizado a partir da determinação das perdas de vitamina C e da eficiência de energética do processo. Verificou-se que a degradação do ácido ascórbico é mais acentuada em leito de fluidizado. Com relação a eficiência energética valores mais elevados foram encontrados em níveis de umidade mais acentuadas. De maneira geral, podemos afirmar que o sistema combinado de secagem de pedaços cúbicos de goiaba aponta de forma promissora para a produção de um novo produto obtido a partir de uma tecnologia simples, obtendo-se produtos com características adequadas à comercialização.
Initially, the objective of this work was to study the drying of whole guava slices cut in the fruit polar direction. The results pointed out that this process introduced adverse aspects for commercialization, such as significant alteration in color, darkness, and slices texture. Looking for a better product quality, studies on combined process fixed bed/spouted bed and fixed bed/fluidized bed for guava cubic pieces drying were performed in a second step. The guava slices were obtained by cutting the fruit pith in approximately 1cm cubic form. A fluid-dynamic study in spouted bed and fluidized bed showed the feasibility of this technique, although the physical properties of guava cubic pieces after pre-drying in fixed bed affected the fluid-dynamics behavior causing structural alteration. The minimum spouting velocity, the maximum spoutable height and the minimum fluidization velocity as well, were determined and the obtained results showed good agreement with literature correlations. In order to characterize the fruit cubic pieces, the physical properties, thermal properties and hygroscopic equilibrium were determined as a function of the moisture content. The results of density and diameter pointed out that the particles were classified as type D according Geldart. In such situation, one may expect a stable spouting with incipient fluidization. In relation to the study of the shrinking and deformation it was observed a linear volume contraction with the moisture reduction at all levels of product moisture content during drying, together with a rapid rounding of the cube vertices. Spite the linear behavior, two distinct regions, limited by 1,5 (db) moisture content, had been observed during the spouted bed drying, characterized by the change in the curve slope. The thermal properties, thermal conductivity, thermal diffusivity and specific heat, were measured as a function of moisture content. All three presented the same trend: it was observed a region of increasing value of the property with the moisture content with a maximum in the region of maximum density. The Henderson model was adjusted to the hygroscopic equilibrium isotherms; the results showed a good fitting and little effect of temperature was observed within the studied temperature range. A diffusional model for spheres was proposed to describe the drying kinetics. The Fick's solution, truncated in four terms of the series and including the shrinking effect, was used in the modeling. The fixed bed/spouted bed experimental data showed a good fitting whereas this model does not satisfactorily predict the drying behavior in the fixed bed/fluidized bed system. The failure in this case is probably due to the shrinking factor was not considered in the model for fixed/fluidized bed. The effective diffusion coefficient for high levels of moisture presented the same order of magnitude for both processes, independent of the bed height. The internal diffusional control hypothesis for the mass transfer was then confirmed by the high mass Biot number, calculated for both processes. The driers performance was evaluated by means of analysis of the vitamin C loss and process energetic efficiency. It was verified that the acid ascorbic degradation is more significant in the fluidized bed, probably due to the instable behavior of this configuration. With regard to the energy efficiency higher values were found for the highest moisture content levels. In general, it is concluded that the combined system fixed/spouted or fixed/fluidized bed drying of guava pieces is an expecting suitable process to obtain a new product by a simple technology, getting products with adequate characteristics to the commercialization.

Les nouvelles molécules thérapeutiques présentent la plupart du temps une faible solubilité aqueuse, à l’origine d’une biodisponibilité restreinte lors de leur administration orale. La réduction de taille des cristaux de substance active à l’échelle submicronique (= production de nanocristaux) s’est imposée comme une voie majeure de formulation au cours de ces dernières années.Afin de pallier des problèmes d’instabilité et d’aboutir à des formes solides pratiques d’utilisation pour les patients, une étape de séchage est généralement effectuée après production des nanocristaux en suspension. L’objectif principal de cette étape est de générer un produit présentant à la fois des propriétés facilitant le déroulement d’étapes procédés avales mais aussi et surtout de prévenir l’agrégation des nanocristaux au risque de compromettre leur dissolution après administration.Plusieurs techniques sont aujourd’hui utilisées dans l’industrie pharmaceutique telle que l’enrobage/granulation en lit d’air fluidisé et le spray drying. Parallèlement à l’élaboration d’une « formulation standard » pour ces deux méthodes de référence, deux techniques innovantes de lyophilisation ont été investiguées dans ce travail. La stabilisation de nanocristaux de kétoconazole par cryopelletization et active freeze drying a été démontrée et les paramètres clefs identifiés. Les produits générés par ces deux techniques, respectivement sous forme de pellets ou de poudre fine, ont été comparés à ceux conçus par enrobage en lit d’air fluidisé et spray drying. En conclusion, ces travaux indiquent que la cryopelletization et l’active freeze drying se positionnent comme des procédés d’intérêt de seconde intention, permettant de traiter des cas particuliers (molécules sensibles au stress thermique, à l’humidité et/ou couteuses)
Newly active pharmaceutical ingredients very often suffer from low aqueous solubility, a fact that in many cases can lead to poor oral bioavailability. Nanosizing, referring to drug nanocrystals production by size reduction, has demonstrated over the past few years a great potential to overcome this major issue.Since solid oral dosage forms are generally preferred due to stability reasons and patient convenience, the production of nanocrystals in a liquid medium is usually followed by a drying step. The main objective of this drying step is to generate a product suitable for downstream processing operations while at the same time preventing nanocrystal aggregation which can adversely affect the dissolution performance of the dry product in vivo.Several drying techniques such as spray drying and coating/granulation in fluidized bed have been successfully implemented in the pharmaceutical industry. In this work, two innovative freeze drying techniques were investigated and compared to the two above mentioned reference methods. The suitability of cryopelletization and active freeze drying to stabilize ketoconazole nanocrystals has been demonstrated and the key process parameters identified. The formulations generated by these two innovative techniques in the form of pellets or fine powder particles, respectively, were compared to the previously manufactured by fluidized bed and spray drying. In conclusion, this work presents cryopelletization and active freeze drying as suitable second-line processes with potential to address the drying of formulations containing problematic molecules sensible to thermal stress, moisture and/or presenting high production costs

Esta tese de doutorado trata do desenvolvimento inédito de formas farmacêuticas sólidas contendo nanocápsulas de núcleo lipídico, facilmente redispersíveis em água, empregando a secagem por aspersão ou granulação em leito fluidizado. A estratégia visa superar limitações tecnológicas associadas às suspensões de nanocápsulas poliméricas, pela sua natureza coloidal, e avançar na fronteira do conhecimento, buscando o desenvolvimento de formulações inovadoras para a administração oral de fármacos. Foram produzidos pós e grânulos contendo nanocápsulas de núcleo lipídico (LNC), empregando a secagem por aspersão e granulação em leito fluidizado, respectivamente. A influência do número de partículas das suspensões de nanocápsulas nas propriedades de redispersão dos pós produzidos pela secagem por aspersão foi investigada. Uma mistura de maltodextrina e L-leucina (90:10 m/m) foi utilizada como adjuvante de secagem. A formulação que obteve os melhores perfis de redispersão consistiu de uma mistura da suspensão de nanocápsulas de núcleo lipídico e de uma solução contendo maltodextrina/L-leucina (10% m/v) em uma proporção 1:1 v/v. Após a redispersão dos pós produzidos em água, 75% do número inicial de partículas de nanocápsulas foi recuperado. Análises de área superficial, microscopia eletrônica de varredura e microscopia confocal Raman permitiram compreender as diferenças na organização estrutural destes pós. Estes dados, em conjunto com análises de diâmetro médio de partículas, obtidos por difratometria de laser, confirmaram a influência do número inicial de partículas das suspensões de nanocápsulas na qualidade de sua redispersão, a partir de formulações sólidas obtidas pela secagem por aspersão. Para compreender as influências dos processos de secagem e redispersão da formulação proposta no perfil de liberação in vitro e na atividade biológica de fármacos associados ao sistema, novos pós foram preparados, substituindo-se a suspensão de nanocápsulas sem fármaco (LNC) por nanocápsulas contendo uma substância ativa modelo (curcumina) (LNC-C 1 mg mL-1). A formulação seca demonstrou adequada redispersão em água e o perfil de liberação in vitro manteve-se semelhante ao da suspensão original (LNC-C), seguindo um modelo cinético de ordem zero. A atividade da curcumina nanoencapsulada foi avaliada empregando um modelo de inflamação induzida por LPS em cultura organotípica de cultura de hipocampo cerebral de ratos. Não houve alterações nas concentrações de biomarcadores pró-inflamatórios (TNF-α e IL-1β) liberados nos meios de cultura, comparando-se as LNC-C em suspensão ou a redispersão dos pós secos. Portanto, a produção de pós facilmente redispersíveis não implica em alterações no controle da liberação in vitro e na atividade biológica da substância ativa nanoencapsulada. Na última etapa, a obtenção dos grânulos empregando granulador em leito fluidizado foi estudada utilizando maltodextrina, como material de suporte, e suspensões de nanocápsulas de núcleo lipídico estabilizadas com polissorbato 80 (LNC) ou com revestimento catiônico (C-LNC), como líquidos aglutinantes. A influência do revestimento catiônico das nanocápsulas nas características tecnológicas dos grânulos obtidos foi avaliada. Propriedades como o tamanho de partícula, rendimento, teor de umidade, características morfológicas, propriedades de fluxo e perfil de redispersão foram estudados. Os rendimentos do processo de granulação foram próximos a 90%, resultando em grânulos com teor de umidade inferior a 4%. Valores calculados de índice de Carr, fator de Hausner e índice de coesão indicaram que as formulações de grânulos propostas neste estudo apresentam melhores características de fluxo em relação à maltodextrina (matéria-prima). O revestimento catiônico das nanocápsulas melhorou tanto as propriedades de fluxo quanto o perfil de redispersão em água dos grânulos contendo C-LNC, demonstrado a partir das análises de diâmetro médio de partículas por difratometria de laser. Em conclusão, os processos de secagem por aspersão e granulação em leito fluidizado, empregados neste estudo, para a produção de formas farmacêuticas sólidas intermediárias e/ou finais contendo nanocápsulas de núcleo lipídico, mostraram-se alternativas viáveis para a produção de pós e grânulos facilmente redispersíveis em água, com potencial aplicação para administração oral de fármacos nanoencapsulados.
This thesis proposes the development of novel easily redispersible solid dosage forms containing lipid-core nanocapsules, produced by spray drying or fluidized bed granulation. The strategy aims to overcome the technological limitations associated to polymeric nanocapsule suspensions, due to their colloidal nature, aiming the development of innovative oral formulations. Powders and granules containing lipid-core nanocapsules (LNC) were produced by spray-drying and fluidized bed granulation, respectively. The influence of the number of particles of the nanocapsule suspensions on the redispersion properties of the spray-dried powders was investigated. A mixture of maltodextrin and L-leucine (90:10 m/m) was used as a drying adjuvant. The formulation that obtained the best redispersion profiles consisted of a mixture of the lipid-core nanocapsule suspension and a solution containing maltodextrin/L-leucine (10% w/v) in a 1:1 v/v ratio. After the aqueous redispersion, 75% of the initial number of particles in the nanocapsules suspension was recovered. Analysis of surface area, by scanning electron microscopy and by Raman confocal microscopy allowed understanding the differences in the structural organization of the powders produced. These results along with the mean diameter analysis by laser diffractometry confirmed the influence of the initial number of particles of the nanocapsule suspensions on the redispersion properties of the spray-dried powders. In order to understand the influence of the drying and redispersion processes on the in vitro release profile and the biological activity of substances associated to this system, new powder formulations were prepared by replacing the unloaded suspension of nanocapsules (LNC) by nanocapsules containing an active substance (curcumin) (LNC-C 1 mg mL-1). The spray-dried powder showed good aqueous redispersion profile and its in vitro release profile remained similar to that of the original LNC-C suspension, according to the zero-order kinetic model. The biological activity of nanoencapsulated curcumin was assessed by a model of LPS-induced inflammation in organotypic hippocampal slice cultures. There were no changes in the concentration of pro-inflammatory biomarkers (TNF-α and IL-1β) released in the culture media, comparing the LNC-C as the initial suspension or the aqueous redispersion of their spray-dried powders. The drying process does not imply changes in the control of in vitro release and in the biological activity of the nanoencapsulated active substance. In the last stage, granules were produced using a fluidized bed granulator and maltodextrin, as support material. Lipid-core nanocapsules suspensions stabilized with polysorbate 80 (LNC) or with a cationic coating (C-LNC) were used as binder liquids. The influence of the cationic coating of the nanocapsules on the technological characteristics of the produced granules was evaluated. Properties such as particle size, yield, moisture content, morphological characteristics, flow properties and redispersion profile were also studied. Granulation process yields were close to 90%, resulting in granules with moisture content of less than 4%. Calculated values of Carr index, Hausner ratio and cohesion index indicated that the granule formulations proposed in this study present better flow characteristics in relation to the maltodextrin raw material. The cationic coating of the nanocapsules improved the flow properties and the aqueous redispersion profile of the granules containing C-LNC, as demonstrated by laser diffraction analysis. In conclusion, the spray-drying and fluidized bed granulation processes used in this study are viable alternatives for the production of easily redispersible powders and granules containing lipid-core nanocapsules, showing potential application for oral administration of drug-loaded lipid-core nanocapsules.

Orientadores: Sandra Cristina dos Santos Rocha, Nadia Rosa Pereira
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-13T12:37:55Z (GMT). No. of bitstreams: 1 Godoi_FernandaCondide_M.pdf: 8309659 bytes, checksum: f684e63fdb8ecb9b104155ad92580055 (MD5) Previous issue date: 2009
Resumo: Polihidroxibutirato (PHB) é um poliéster completamente biodegradável e biocompatível. O interesse no desenvolvimento, produção e comercialização do PHB vem crescendo por ser um produto biodegradável e de produção integrada à cadeia de açúcar e álcool. A secagem é uma importante etapa do processo de produção do PHB, pois para o adequado pósprocessamento desse material deve-se garantir um teor de umidade limite de 0,5%. Neste contexto, este trabalho teve como objetivo estudar uma tecnologia de secagem, em um produto inovador e de importância na preservação ambiental. Foi realizado um estudo da fluidodinâmica e dos mecanismos de secagem do PHB em um leito fluidizado pulsado rotativo (LFPR). A escolha do equipamento baseou-se no fato de que o PHB úmido é coesivo e não apresenta fluidização convencional de qualidade. O secador de LFPR utiliza a pulsação do ar para desfazer os aglomerados de PHB melhorando a circulação das partículas dentro do leito. O presente estudo também incluiu a caracterização física do material antes e após a secagem. Para os ensaios de caracterização em que os equipamentos não trabalham em presença de umidade, a liofilização do PHB foi a alternativa encontrada para se caracterizar o material antes da secagem. O PHB apresentou um excelente comportamento fluidodinâmico em LFPR. A frequência de pulsação de 10 Hz foi a que apresentou comportamento mais favorável, com queda de pressão moderada e patamares de estabilidade. Por meio dos ensaios fluidodinâmicos foi possível determinar a velocidade de mínima fluidização vigorosa pulsada (VMV), parâmetro que ajudou a estabelecer a velocidade empregada para os experimentos de secagem. Durante a secagem do PHB foi avaliada a influência que a temperatura, velocidade e frequência de pulsação do ar exercem na cinética de secagem. Verificou-se excelente contato entre as partículas de PHB e o ar aquecido, com elutriação somente nos primeiros 10 minutos de secagem. As curvas de secagem do PHB indicaram períodos de taxa de secagem constante e decrescente. A temperatura e a velocidade do ar influenciaram positivamente o processo. Além disso, foi detectada a existência de um outro solvente além da água nas amostras de PHB, por meio da comparação entre as curvas de secagem obtidas com medidas de umidade feitas em estufa e em Karl Fischer. A análise termogravimétrica (TGA) também ajudou a detectar a presença de outro solvente além da água nas amostras de PHB. Os ensaios de caracterização física mostraram que as condições operacionais de secagem testadas não provocaram a degradação das partículas de PHB. Sob as condições consideradas ótimas de secagem, temperatura de 90 ºC, frequência de 7 Hz e velocidade do ar 0,40 m/s, foi atingida umidade igual a 0,56%, demonstrando a viabilidade do secador LFPR.
Abstract: Poly-hydroxybutyrate (PHB) is polyester, completely biodegradable and biocompatible. The interest on its development, production and commercialization has arisen due to its biodegradability and production integrated to the sugar and alcohol chain. Drying is an important step of the PHB production because an adequate post-processing is achieved only at moisture contents less than 0.5%. The goal of this work was to study a drying technology for this innovative product of relevant importance for the environmental preservation. The fluid-dynamic and drying mechanisms analyses were made in a rotating-pulsed fluidized bed (RPFB). The equipment was chosen based on the fact that the wet PHB is cohesive and doesn't work properly in a conventional fluid bed. The RPFB dryer uses the air pulsation to undo the PHB agglomerate improving the circulation of the particles inside the bed. This study also included the physical characterization of the material before and after the drying. For the characterization tests that wouldn't work with moisture presence, the liophilization was the best alternative to characterize the material before the drying process. The PHBshowed an excellent dynamic behavior in RPFB. The pulsation frequency of 10 Hz presented the most favorable fluid dynamic conditions, resulting in moderate pressure drop and regime stability. Based on the fluid-dynamic study it was possible to determine the minimum vigorous fluidizing air flow (MVF), an important parameter to set the air velocity range for the drying experiments. An excellent contact between the PHB particles and the hot air was obtained during the drying runs, with particles elutriation only during the first 10 minutes. The influence of the temperature, velocity and frequency of air pulsation was evaluated on the drying kinetics. The PHB drying kinetics presented constant and decreasing-rate drying periods. The drying process was positively influenced by the air temperature and velocity. Furthermore, the presence of another solvent additionally to the water was detected in the PHB samples through the comparison between the drying curves obtained with moisture measurements made in an oven and in Karl Fischer equipment. The thermo gravimetric analysis also helped to detect the presence of another solvent in the PHB samples. The physical characterization tests showed that the drying operating conditions didn't cause degradation on PHB particles. The RPFB dryer showed to be a viable technique to dry PHB, as moisture content of 0.56% was reached at optimal operating conditions of air temperature of 90oC, air velocity of 0,40 m/s and frequency of pulsation of 7 Hz.
Mestrado
Engenharia de Processos
Mestre em Engenharia Química

O presente trabalho refere-se ao desenvolvimento de grânulos a partir de produto seco de A. satureioides obtido por spray drying, em escala semi-industrial, visando a superar as principais limitações tecnológicas apresentadas tais como a higroscopia excessiva do produto, baixa densidade, pequeno tamanho de partícula e instabilidade dos constituintes flavonoídicos frente à luz. Dois métodos foram empregados para a granulação: granulação em leito fluidizado e granulação via seca por desagregação. Estes métodos apresentaram, respectivamente, 15 e 60 % de rendimento do processo, levando a escolha da granulação seca para a produção dos grânulos do produto seco. A granulação seca resultou em grânulos assimétricos, de faixa granulométrica situada entre 0,3 mm e 1,9 mm e de superfície irregular e rugosa. O revestimento destes grânulos foi realizado em leito fluidizado, utilizando três tipos de polímeros, Eudragit® L 30D, Opadry® II e Opadry® AMB.O rendimento médio com o Opadry® II foi de 72 %. O revestimento com Opadry® AMB foi realizado utilizando-se um baixo e alto fluxo do líquido de revestimento, obtendo-se rendimentos de 75 e 85 %, respectivamente. A higroscopia dos grânulos foi avaliada em ambientes com umidade relativa controlada de 65 ou 99 %, comparando-se o comportamento dos grânulos revestidos com o dos grânulos sem a presença de revestimento. Ambos os filmes com Opadry® não protegeram os grânulos frente à umidade. As fotomicrografias por MEV, destes grânulos, revelaram que, ambos os tipos de revestimento, apresentaram superfícies rugosas e com presença de poros explicando, parcialmente, a falta de proteção contra a umidade. O estudo da fotoproteção indica, em um primeiro momento, que o filme de revestimento promove a proteção dos flavonóides frente a ação da luz. A avaliação preliminar da liberação dos flavonóides, a partir dos grânulos, foi realizada em células de fluxo Desaga® com os grânulos sem revestimento e revestidos com Opadry® AMB. A água não demonstrou ser o meio mais favorável para este ensaio. Em meio com pH 1,2 contendo 1 % de laurilsulfato de sódio, os flavonóides quercetina, luteolina e 3-Ometilquercetina foram liberados, respectivamente, após 90 minutos, em 70, 83 e 70 % a partir dos grânulos não revestidos, e 52, 54 e 45 % a partir dos grânulos revestidos com Opadry® AMB, denotando a influência do filme de revestimento sobre o perfil de liberação dos flavonóides. Em seu conjunto, os resultados obtidos nesta primeira abordagem deste tema abrem diversas perspectivas para oaprofundamento do estudo e desenvolvimento de granulados de A. satureioides, a partir de produto seco por spray drying.
The present work was designed to develop granules from Achyrocline satureioides spray dried powders in order to overcome the main technological limitations presented by this herbal raw material: high hygroscopy, low density, small particle diameter and flavonoid sensibility against light. Two methods were employed for granulation, fluidized bed and dry granulation. These methods presented, respectively, 15 and 60 % of process yield, leading to the selection of dry granulation for preparing the granules. By this method, the granules showed 0,3 to 1,9 mm particle mean diameter, rough surface and irregular morphology. For coating the granules, three types of polymers were employed, Eudragit® L30D, Opadry® II and Opadry® AMB, in fluidized bed. The first one resulted in atomizer obstruction becoming non viable its employment. The mean yield coating obtained with Opadry® II was 72 %. The Opadry® AMB was sprayed in low and high rates yielding, respectively, 75 % and 85 %. The hygroscopicity of the granules was evaluated in controlled conditions of 65 % or 99 % RH, comparing the behavior of the coated granules which that presented by non-coated particles. Both Opadry® coatings did not protect the granules against the humidity. The SEM photomicrographis of these granules revealed that both types of coating presented rough and porous surface explaining partially, at least, the lack of protection against the humidity. The preliminary photostability assay indicated, in a first view, that the coating promotes the flavonoid protection. The flavonoid release from the granules was performed in Desaga® flow cell from the non-coated granules and from Opadry® AMB coated granules. Water demonstrated not to be an appropriate media for both tested granules. In pH 1.2 media containing 1 % of sodium lauryl sulfate, the flavonoids quercetin, luteolin and 3-O-methylquercetin were, respectively, released, after 90 minutes, in 70 %, 83 % and 70 % from non coated granules and in 52 %, 54 % and 45 % from Opadry® AMB coated granules, denoting the influence of the coating on the flavonoid release profile. Taken together, the results of this first approach openmay perspectives for more detailed studies on Achyrocline satureioides granules from the corresponding spray dried powders.

L'étude des phénomènes fondamentaux de

transport et de thermodynamique apparaissant lors de l'évaporation

en milieu poreux permet l'investigation d'applications pratiques

variées. Dans ce travail, nous développons des modèles fondamentaux

d'évaporation en milieu poreux que nous appliquons ensuite au

séchage en lit fluidisé de deux matériaux granulaires poreux :le

PVC et la levure.

Les modèles mis au point sont réalisés suivant une approche

multiéchelle. Nous nous intéressons tout d'abord aux phénomènes se

déroulant à l'échelle d'un pore. Les modèles développés à cette

échelle sont ensuite exploités dans le cadre d'une étude à l'échelle

d'un grain poreux. Le couplage des modèles de grain avec un modèle à

l'échelle du réacteur permet alors l'étude des applications

industrielles.

A l'échelle du pore, nous étudions les phénomènes de transport dans

un capillaire initialement rempli de liquide qui s'évapore vers

l'atmosphère ambiante. L'objectif est de prédire le taux

d'évaporation dans cette configuration. Nous nous intéressons

successivement à la modélisation du transport de matière par

convection-diffusion en phase gazeuse et la modélisation de l'impact

de films liquides adsorbés à la paroi du capillaire sur le transport

de matière. Ces deux modèles sont confrontés à des expériences

d'évaporation en capillaires cylindriques visualisées à l'aide de

deux dispositifs optiques. Le premier offre un suivi d'ensemble au

cours du temps du capillaire, alors que le second, un interféromètre

de Mach-Zehnder, permet une visualisation locale de la région

entourant le ménisque.

Le modèle portant sur le transport de matière par

convection-diffusion mène à la définition d'un critère non

dimensionnel permettant d'évaluer si la convection dans la phase

gazeuse dans le capillaire doit être prise en compte pour évaluer le

taux d'évaporation. Le modèle de film permet de prédire l'impact de

celui-ci sur l'évaporation en présence d'un gaz inerte lorsque les

mouvements convectifs en phase gazeuse sont négligeables. La

confrontation de ce modèle avec les profils d'épaisseur des films

obtenus à l'aide de interféromètre de Mach-Zehnder ne permet pas de

valider le modèle, et ce, suite à une trop grande incertitude sur

l'évaluation des interactions entre la paroi et le liquide.

A l'échelle d'un grain, nous développons un modèle discret par

réseau de pores et deux modèles continus pour tenter de prédire le

taux d'évaporation et la distribution des phases dans le milieu

poreux. Le modèle par réseau de pores prend en compte les transports

de matière par diffusion en phase gazeuse, par convection dans les

pores remplis de liquide et par convection dans les films liquides.

Les effets visqueux en phase liquide sont également modelisés. Pour

la prise en compte de ces derniers, nous montrons l'importance de

l'usage d'un algorithme approprié. Nous évaluons ensuite au travers

de trois nombres sans dimensions l'impact du transport par film et

des effets visqueux sur l'évaporation et la distribution des phases.

Cette analyse dimensionnelle est ensuite appliquée à l'étude de

réseaux de pores pour lesquels la section des liaisons les

constituant est idéalisée par des polygones réguliers. Pour les

modèles continus après une vérification simplifiée de

l'applicabilité de cette démarche, nous développons deux modèles

simples. Dans les deux modèles, l'étape de séchage à vitesse

constante est supposée limitée par le transport de matière externe

au grain. Le premier modèle, dit à front pénétrant, suppose que

l'étape de séchage à vitesse décroissante correspond à l'existence

d'un front d'évaporation qui s'enfonce dans la matrice poreuse. Le

second modèle, dit à surface d'échange variable, attribue cette même

étape du séchage à une diminution progressive de la surface

d'évaporation en surface du grain.

A l'échelle du réacteur, nous présentons deux modèles visant à

simuler deux types d'essais différents :le séchage en lit fluidisé

et la thermogravimétrie analytique. Ces deux modèles sont couplés

aux différents modèles à l'échelle de grain pour étudier le séchage

de PVC et de levure tant en lit fluidisé que lors des essais de

thermogravimétrie analytique.

Dans le cas du PVC, le modèle par réseau de pores ne peut pas être

appliqué de par la nécessité d'une trop grande puissance de calcul.

Au niveau des modèles continus, nous montrons que l'application du

modèle à surface d'échange variable permet de reproduire les courbes

de séchage expérimentales des essais en lit fluidisé.

Dans le cas de la levure, nous appliquons le modèle par réseau de

pores et le modèle à front pénétrant. L'utilisation du modèle par

réseau de pores nécessite une connaissance plus détaillée de la

structure poreuse des grains. Le traitement d'une analyse par

microtomographie nous permet d'obtenir un réseau de pores

expérimental. Celui-ci est utilisé pour montrer que la méthode de

caractérisation de la porosité par intrusion de mercure ne semble

pas adaptée à un matériau deformable comme la levure. Le même réseau

est utilisé pour simuler le séchage de grains de levure à l'aide du

modèle par réseau de pores. Les simulations sont réalisées sur des

réseaux équivalents à des coupes dans le solide. Le modèle par

réseau de pores et le modèle à front pénétrant permettent tous deux

de modéliser correctement le séchage de levure en lit fluidisé

moyennant l'ajustement de leurs paramètres ajustables,

respectivement la conductibilité des films liquide et la tortuosité.

Pour l'essai de thermogravimétrie, ils ne parviennent à approcher

que la première étape de celui-ci. Les avantages, défauts et

complémentarités de ces deux modèles sont discutés.

Nous évaluons ensuite l'impact du rétrécissement de la levure et des

types d'eau sur le séchage de ce matériau. Le rétrécissement est,

pour ce faire, mesuré à l'aide d'un stéréomicroscope. Ces premières

mesures, exploratoires, mènent à la définition d'un modèle empirique

de retrait du solide au cours de son séchage. En le prenant en

compte dans les modèles déjà appliqués à la levure, nous montrons

que le retrait a un impact significatif sur l'étape de séchage à

vitesse décroissante. Cet impact

peut cependant être masqué intégralement par la réévaluation

des paramètres ajustables des différents modèles. Finalement,

l'étude des types d'eau au travers d'un modèle simple appliqué à

l'essai de thermogravimétrie analytique montre que les types d'eau

ne doivent pas être pris en compte pour modéliser le séchage de

levure.

A l'issue de ce travail, nous disposons donc de modèles fondamentaux

d'évaporation en milieu poreux. Ceux-ci peuvent être appliqués à des

cas d'intérêt industriel, comme nous le réalisons pour le PVC et la

levure. Ils peuvent servir à améliorer la

compréhension de ces procédés. Ils représentent donc des

outils de choix pour la conception, le dimensionnement et

l'optimisation du séchage.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Orientador: Antonio Carlos Luz Lisboa
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Xisto pirobetuminoso é uma rocha sedimentar que contém querogênio, um material orgânico que se encontra disseminado em sua estrutura mineral. O querogênio é extraído por aquecimento a altas temperaturas, em reatores conhecidos como retortas, 1iberando óleo e gás. Este óleo quando refinado produz destilados com as mesmas características encontradas nos de petróleo, sendo considerado uma fonte de energia alternativa. A existência de umidade no xisto na entrada do reator gera uma zona de secagem influenciando na redução da temperatura dos gases e diminuição da eficiência da retorta. O objetivo deste trabalho é investigar a perda de umidade durante a secagem de partículas de xisto, visando conhecer os mecanismos envolvidos. Para obter o perfil de umidade ao longo do tempo foram utilizadas partículas classificadas em três diferentes lotes quanto ao diâmetro médio de partícula (dp): partículas individuais do Lote A (dp = 80 mm e dp = 60 mm); partículas do Lote B que subdivide-se em quatro sublotes (~ = 5,3 mm, dp = 3 mm, dp = 1,5 mm e dp = 0,85 mm) e partículas do Lote C (dp < 0,074 mm). Os experimentos de secagem foram realizados em diversos secadores: partículas do Lote A secas em estufa com circulação de ar a 60°C e 90°C; partículas do Lote B secas em bandeja termogravimétrica a 40°C, 60 °c, 80°C e 100°C e em leito de jorro e leito fluidizado a 50°C e 70°C; partículas do Lote C secas em um analisador termogravimétrico, cujas temperaturas iniciais de 20°C variaram ao longo do tempo até atingir valores máximos de 40 °C, 70°C e 100°C. Exceto os experimentos realizados no ana1isador termogravimétrico, em todos os demais a temperatura foi mantida constante. Utilizou-se o modelo matemático de difusão de Fick, considerando geometrias uni e tri-dimensionais. Na solução destes modelos foram desenvolvidos programas em linguagem Fortran para descrever a variação de umidade das partículas de xisto ao longo do tempo e da posição, levando-se em conta a geometria da partícula e a temperatura do ar de secagem (constante ou variável). Os resultados preditos pelos modelos foram comparados com os experimentais apresentando boa concordância. Estes modelos podem contribuir na estimativa de parâmetros desconhecidos do processo. Quanto ao leito em jorro e leito fiuidizado, verificou-se que são técnicas adeqüadas para a secagem de xisto
Abstract: Oil shale is a sedimentary rock which contains kerogen, an organic matter scattered througout a mineral matrix. Kerogen is extracted by pyrolysis at high temperatures in reactors known as retorts producing oil and gas. The oil, when refined, produces distillates with the same characteristics as petroleum. Oil shale is considered an alternative energy source to petroleum. At the top of a moving bed retort oil shale moisture vaporization consumes energy, thereby reducing the retort efficiency. Oil shale drying has been investigated to optimize pyrolysis. The objective of this work was to investigate the moisture loss during oil shale particles drying to know the mechanisms involved. In order to obtain the moisture profile with time particles classified in three different categories
Doutorado
Engenharia de Processos
Doutor em Engenharia Química

Resumo: Neste trabalho foi construído e desenvolvido um secador de leito pulso-fluidizado que utilizou partículas inertes para a secagem de pastas e polpas de frutas. O sistema permitia o controle da vazão do ar de fluidização e de sua temperatura, da pulsação do ar e da vazão de injeção de pasta. Foram determinadas as curvas de fluidização de partículas de vidro e teflon no leito pulso-fluidizado sob diferentes configurações, bem como suas velocidades de mínima fluidização, as quais demonstraram-se próximas às curvas de um secador fluidizado convencional. Experimentos para a avaliação da agitação das partículas foram realizados para que fossem encontradas as melhores condições, determinando-se a existência ou não de pontos mortos no leito. Foi visto que as partículas pertenciam ao grupo D, segundo a classificação de Geldart (1973). Pasta de gesso foi seca no secador pulso-fluidizado para avaliação da produção de pó e do hold-up das esferas nas diferentes condições de operação, as quais tiveram como variáveis os períodos de injeção (fase ativa e inativa), ângulo da válvula borboleta que dava acesso do ar ao leito, temperatura do ar de secagem, velocidade do ar e vazão de pasta no leito. Foi observado que todas as variáveis testadas apresentaram influência na produção de pó e na quantidade de material aderido às partículas inertes. O secador pulsofluidizado foi testado também na secagem de suco e pastas de limão, maltodextrina e tomate, mostrando problemas de adesividade e, no caso de derivados de limão, aglomeração das partículas e colapso do leito. O secador foi utilizado ainda como vibro-fluidizado, quando o sistema de pulsação foi desligado e um sistema de vibração por eixos excêntricos foi acionado, constatando-se que o mesmo apresentou rendimento inferior ao pulso-fluidizado. Um secador do tipo spray dryer foi usado para a secagem... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: For this work, a pulse fluidized bed drier that used inert particles for drying pastes and fruit pulps was constructed and developed. The system allowed for the control of fluidized air flow and its temperature, the air pulses and the paste injection flow. The fluidization curves and minimum velocity of fluidization of glass and Teflon particles were determined in the pulse fluidized bed. Experiments to evaluate the agitation of particles were done to find the best agitation conditions, determining the existence or not of dead spots in the bed. It was seen that the particles belonged to D group, as per Geldart (1973) classification. Plaster paste was dried in the pulse fluidized dryer to evaluate the production of powder and hold-up of the spheres under different operational conditions which were variations of the periods of paste injection (active and inactive phase), angle of the butterfly valve which gave air access to the bed, air drying temperature, air speed and paste flow. All tested variables influenced the powder production and the amount of material adhered to inert particles. The pulse fluidized bed drier was also tested for drying lemon juice and paste, maltodextrina and tomato, showing adhesive problems and, with the lemons, an agglomeration of particles and a collapsed bed. The dryer was also used as a vibro fluidized bed when the pulsation system was turned off and a vibration system with eccentric axles was set in motion, it was seen that the vibro fluidized bed had a lower yield than the pulse fluidized bed. A spray drier was used to dry lemon juice with maltodextrina, and it was found that a minimum of 65% of additional maltodextrina was needed. Physic-chemical testes were done from the powders obtained from the spray drying. These testes were for humidity, flowability, degree of agglomeration, higroscopicity, dispersibility, color determination and water activity... (Complete abstract click electronic access below)
Orientador: Javier Telis Romero
Coorientador: João Cláudio Thoméo
Banca: Luis Alexandre Pedro de Freitas
Banca: Maria Aparecida Mauro
Mestre

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho foi construído e desenvolvido um secador de leito pulso-fluidizado que utilizou partículas inertes para a secagem de pastas e polpas de frutas. O sistema permitia o controle da vazão do ar de fluidização e de sua temperatura, da pulsação do ar e da vazão de injeção de pasta. Foram determinadas as curvas de fluidização de partículas de vidro e teflon no leito pulso-fluidizado sob diferentes configurações, bem como suas velocidades de mínima fluidização, as quais demonstraram-se próximas às curvas de um secador fluidizado convencional. Experimentos para a avaliação da agitação das partículas foram realizados para que fossem encontradas as melhores condições, determinando-se a existência ou não de pontos mortos no leito. Foi visto que as partículas pertenciam ao grupo D, segundo a classificação de Geldart (1973). Pasta de gesso foi seca no secador pulso-fluidizado para avaliação da produção de pó e do hold-up das esferas nas diferentes condições de operação, as quais tiveram como variáveis os períodos de injeção (fase ativa e inativa), ângulo da válvula borboleta que dava acesso do ar ao leito, temperatura do ar de secagem, velocidade do ar e vazão de pasta no leito. Foi observado que todas as variáveis testadas apresentaram influência na produção de pó e na quantidade de material aderido às partículas inertes. O secador pulsofluidizado foi testado também na secagem de suco e pastas de limão, maltodextrina e tomate, mostrando problemas de adesividade e, no caso de derivados de limão, aglomeração das partículas e colapso do leito. O secador foi utilizado ainda como vibro-fluidizado, quando o sistema de pulsação foi desligado e um sistema de vibração por eixos excêntricos foi acionado, constatando-se que o mesmo apresentou rendimento inferior ao pulso-fluidizado. Um secador do tipo spray dryer foi usado para a secagem...
For this work, a pulse fluidized bed drier that used inert particles for drying pastes and fruit pulps was constructed and developed. The system allowed for the control of fluidized air flow and its temperature, the air pulses and the paste injection flow. The fluidization curves and minimum velocity of fluidization of glass and Teflon particles were determined in the pulse fluidized bed. Experiments to evaluate the agitation of particles were done to find the best agitation conditions, determining the existence or not of dead spots in the bed. It was seen that the particles belonged to D group, as per Geldart (1973) classification. Plaster paste was dried in the pulse fluidized dryer to evaluate the production of powder and hold-up of the spheres under different operational conditions which were variations of the periods of paste injection (active and inactive phase), angle of the butterfly valve which gave air access to the bed, air drying temperature, air speed and paste flow. All tested variables influenced the powder production and the amount of material adhered to inert particles. The pulse fluidized bed drier was also tested for drying lemon juice and paste, maltodextrina and tomato, showing adhesive problems and, with the lemons, an agglomeration of particles and a collapsed bed. The dryer was also used as a vibro fluidized bed when the pulsation system was turned off and a vibration system with eccentric axles was set in motion, it was seen that the vibro fluidized bed had a lower yield than the pulse fluidized bed. A spray drier was used to dry lemon juice with maltodextrina, and it was found that a minimum of 65% of additional maltodextrina was needed. Physic-chemical testes were done from the powders obtained from the spray drying. These testes were for humidity, flowability, degree of agglomeration, higroscopicity, dispersibility, color determination and water activity... (Complete abstract click electronic access below)

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The oral administration of drugs for systemic effects is the most common way used in medical treatment. Among these, drugs as tablets are the most used. The granulation is a process that seeks to improve the transportation of powder in the compacting machine by the agglomeration of particles. The fluidized bed drying added to "spray dryer" technique is commonly used to form granules that reaches the required characteristics of a uniform grain, with strict control of final humidity of the granules and relatively short process when compared to other techniques for drugs production. Metformin is a drug displayed as hydrochloride and orally administered as coated tablets. It is indicated for the treatment of type 2 Diabetes mellitus. In order to improve productivity in an industrial fluidized bed used in the granulation and drying of Metformin, it is necessary to evaluate the effects of operation conditions used in the process, as particulate material and in the production process. For that purpose, it was performed the study of fluiddynamic granulation and drying of Metformin in fluidized bed in order to investigate the minimum fluidization velocity for the process of this drug. The influence of temperature and speed of drying air in processing time of the formula, and the average particle size were also evaluated. The experiments were elaborated based on the Evolutionary Operation Theory, proposed by Box (1957). It performed the shaping at drying stage. With these experiments was possible to reduce to zero the reworks of batches caused by the formation of preferential channels, which could occur deposition polymer solution on the particulate material. It was also possible to reduce the average processing time in 8 minutes, adding greater productivity and savings for the company where the work was developed. The results achieved, besides the gain in productivity, guide to where efforts should be directed to continue improving productivity, providing a practical methodology for applying the technique that can be applied in the production of other drugs that use the granulation process in fluidized bed.
A administração de fármacos para efeitos sistêmicos por via oral é a forma mais comum dentre os medicamentos. Dentre estes, os medicamentos na forma de comprimidos são os mais empregados. A granulação é um processo que visa melhorar o transporte do pó na máquina compressora por meio da aglomeração de partículas. A secagem em leito fluidizado acoplado à técnica de spray dryer é a técnica comumente empregada para a formação de grânulos que atendam as características necessárias de granulometria uniforme, com controle rigoroso da umidade final do granulado e tempo relativamente curto de processo quando comparado a outras técnicas para produção de medicamentos. A metformina é um fármaco, apresentado na forma de cloridrato, e administrado como comprimidos revestidos por via oral. É indicado no tratamento de diabetes, mais especificamente diabetes mellitus tipo 2. Com o objetivo de aprimorar a produtividade em um leito fluidizado industrial utilizado na granulação e secagem de metformina, faz-se necessário avaliar os efeitos das condições operacionais utilizadas no processo referentes a qualidade material particulado e o processo de produção propriamente dito. Para tanto, realizou-se o estudo fluidodinâmico da granulação e secagem de metformina em leito fluidizado investigando assim a velocidade mínima de fluidização para o processamento deste fármaco. A influência da temperatura e da velocidade do ar de secagem no tempo de processamento da fórmula e no tamanho médio da partícula também foram avaliados. Os experimentos foram elaborados a partir da teoria da Operação Evolutiva, proposta por Box (1957). A modelagem da etapa de secagem também foi realizada. Por meio dos experimentos realizados conseguiu-se reduzir a zero os reprocessos de bateladas por formação de canais preferenciais, onde poderia ocorrer deposição de solução polimérica sobre o material particulado. Foi possível também reduzir o tempo médio de processamento em 8 minutos, agregando maior produtividade e economia para a empresa na qual este trabalho foi desenvolvido. Os resultados obtidos mostram que houve ganhos em relação a produtividade, e norteiam para onde os esforços devem ser direcionados para continuidade do melhoramento de produtividade, fornecendo uma metodologia prática para aplicação da técnica que poderá ser aplicada na produção de outros fármacos que utilizam o processo de granulação por via úmida em leito fluidizado.

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Os microrganismos, além de sua importância industrial na obtenção por via biotecnológica de diversos produtos, podem ser utilizados diretamente como alimento para humanos e animais. Neste contexto, vem crescendo o interesse pelo aproveitamento de fontes proteicas não tradicionais, na formulação de ração animal. A utilização de leveduras, tem por meta suprir a carência de proteínas e vitaminas BI. A operação de secagem é importante porque prepara o produto com as características necessárias para atender as exigências de mercado e dentro deste contexto, o leito de jorro e leito fluidizado podem ser utilizados como mais uma opção dentro dos diversos tipos de secadores ora empregados nesta operação. A matéria prima utilizada neste trabalho foi à levedura do gênero Saccharomyces cerevisiae prensada do tipo comercial (fermento biológico fresco da marca Fleischmann"), com umidade média de 70% em base úmida, de cor creme, e granulometria média de 0,991 mm. Os experimentos de secagem de levedura foram realizados em leito de inertes constituído de partículas de poliestireno de 3,26 mm em coluna de 10,3 cm de diâmetro e 25,3 cm de altura. Inicialmente foram levantados dados de equilíbrio higroscópico da levedura a 25, 30, 40 e 49 °C e as isotermas de dessorção obtidas foram ajustadas pelos modelos de GAB e BET Numa segunda etapa, foi estudada a fluidodinâmica do leito de jorro e leito fluidizado para analisar o efeito da presença de leveduras sobre o comportamento do leito de inertes e definir as condições mínimas de operação de modo a estabelecer a matriz de planejamento fatorial. Com o objetivo de analisar e comparar o desempenho dos leitos fluidodinamicamente ativos foi estudada a secagem em leito de jorro e leito fluidizado. Para isto, foi seguido um planejamento fatorial tendo como variáveis de entrada a velocidade do ar e a quantidade de leveduras alimentada, e, como respostas, o rendimento, retenção, perdas, umidade do produto e teor de proteínas. A temperatura foi fixada entre 38 e 44 °C. para todos os experimentos. As taxas instantâneas de evaporação de água apresentaram flutuações na maioria dos ensaios, tanto em leito de jorro como em leito fluidizado, as eficiências energéticas de secagem foram relativamente baixas nos dois processos, em torno de 5 a 50%. A cinética de produção de pó mostrou comportamento crescente e praticamente linear em todos os experimentos. Foi obtido nos ensaios em leito de jorro, um conteúdo de umidade no produto entre 11,65 a 31,34%, em base úmida, e teor proteínas entre 50,09 e 52,68%. Para o leito fluidizado em 7,98 a 48,72% de umidade e 40,6 a 49,7% de proteínas Diante do exposto, o secador de leito de jorro apresentou melhor desempenho, visto que, na qualidade do produto, a umidade e teor de proteínas apresentaram melhores resultados, e um maior rendimento e menor retenção de pó. Comparado com outros secadores, apresentou desempenho maior em termos de proteínas e performance, sendo recomendado estudar o processamento com temperaturas maiores de modo a reduzir o teor de umidade do produto.
Microorganisms, aside from their industrial importance in obtaining several products by biotechnology, can be used directly as food for humans and animals. In this context, an interest in non-conventional sources of protein for animal feed has been growing. The use of yeasts has the aim of supplying the proteins and vitamin B1 requirement. The drying operation is important because it prepares the product with the characteristics necessary for attending to the market demands and in this context the spouted bed and the fluidized bed can be used as one more option in the various types of dryers used in this operation. The raw material used in this work was pressed Saccharomyces cerevisiae commercial type yeast (fresh biological Fleischmann yeast), with an average moisture of 70% in a wet base, cream-colored, and an average size of 0.991 mm. The yeast drying experiments were performed in inert beds constituted by polystyrene particles of 3.26 mm in a column of 10.3 cm of diameter and 25.3 cm of height. The yeast was fed at the top of the column in an intermittent regime. Initially data of hygroscopic equilibrium of the yeast were studied at 25. 30, 40 and 49 °C and the obtained desorption isotherms were adjusted by the GAB and BET models. In a second stage, the fluid dynamics of the spouted bed and the fluidized bed was studied to analyze the effect of the presence of yeast on the behavior of the inert particles bed and to define the minimal operating conditions so that the matrix of factorial design was established. With the objective of analyzing and comparing the performance of the dynamically active beds, the drying of yeast in the spouted and the fluidized bed was studied. For this, a factorial experimental design was followed. The input variables were the velocity of the air and the quantity of yeast fed and as response variables the product yield, retention, loses, moisture and protein content of the dried yeast. The temperature was fixed between 38 and 44 °C for all the experiments. The instant water evaporation rate presented fluctuations in most of the experiments, both in the spouted bed and in the fluidized bed. The drying energy efficiency was relatively low in both processes, in turn of 5 and 50 %. The powder production kinetics showed an increasing and practically linear behavior in all the experiments. The moisture content of the product varied between 11.65 and 31.34% in a wet base and a protein content between 50.09 and 52.68% was obtained in the spouted bed tests. For the fluidized bed a 7.98 to 48.72% moisture and 40.6 to 49.7% proteins were obtained. The spouted bed dryer presented a better performance, inasmuch as, in the quality of the product, the moisture and the protein content presented best results and a greater yield and less retention of powder. Compared to other dryers, it presented a better operation in terms of protein and performance. It is recommended to study the process in a higher temperature interval so as to reduce the moisture content of the product.

Fluidised bed drying is currently receiving much attention as a dewatering option after the beneficiation of fine coal (defined in this study as between 1mm and 2mm particles). The aim of this study was to investigate the removal of moisture from fine coal by using air at relatively low temperatures of between 25°C and 60°C within a controlled environment by lowering of the relative humidity of air. The first part of the experimental work was completed in a controlled climate chamber with the coal samples in a static non-fluidised state. Drying in the second part was carried out using a fluidised bed with conditioned air as the fluidising medium. Introduction of airflow to the system led to a lower moisture content in the coal samples and it also proved to have the ability to increase the drying rate. It was determined that the airflow had the ability to remove more free moisture from the filter cake. In addition more inherent moisture could also be removed by using upward flowing air, resulting in a lower equilibrium moisture content. It was proven that the airflow rate and relative humidity of the drying air contributed to faster drying rates. The effect of temperature was not as significant as expected, but higher temperatures did increase the drying rate at higher airflow and lower humidity conditions. The larger surface areas of particles create surface and capillary forces that prevent the moisture from leaving the finer coal particles. It was found that the rate of drying is independent of the moisture content in the coal sample. Just in terms of the fastest drying time and drying rate in the fluidised bed, it was concluded that the most efficient conditions is airflow above minimum fluidisation point causing vigorous mixing and maximum contact with the drying air. In addition to the high airflow it was concluded that 30% relative humidity and 55°C resulted in the fastest drying time. All the drying processes at all the airflow rates, temperature and relative humidity conditions were energy efficient. This process was shown to be energy positive, resulting in an overall energy gain. The overall energy consumption for the fluidised bed is lower than for all the dryer systems compared to and it compared favourably with other thermal drying technologies. It was therefore shown that this is a viable technology for the dewatering of fine coal.
MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

碩士
輔仁大學
食品科學系碩士班
104
Wheat germ (WG) is a highly nutritive part of wheat kernels, separated during milling as a by-product. Improper drying of WG results in acceleration of molds growth or lipid oxidation. Fluidized bed dryer (FBD) is preferred due to its even thermal distribution and short residence time. To obtain a final product with the desired moisture content (MC) and water activity (Aw) within a required time, precise understanding and control of the relationship between drying variables are vital. Industrial FBDs often allow their final product to cool down before collection, to prevent any surge of moisture absorption or condensate productions. Focusing only on the drying behavior would therefore not be sufficient. The objective of this study were to investigate the behaviors of WG during the drying process in a vertical batch FBD and to develop a model to simulate the drying process, to significantly reduce the amount of physical trial and errors often required. The model was solved using the Finite Element Method with COMSOL software. The system air temperature and humidity were observed experimentally by varying different parameters, i.e. heater temperature （50, 80 and 120 oC）, air velocity （1.21 and 3.62 m/s）, drying profile and WG particle size distribution. WG were sampled at specific time intervals with their MC and Aw measured. The experiment was designed to obtain a final product at around 40 oC with Aw of 0.3 ± 0.1. Results showed an increase in heater temperature from 50 to 120 oC, would reduce heating time from 15 to 1 minutes while the cooling time increases from 4 to 20 minutes, in order to obtain final product of the required specification. Maximizing the heater output (120 oC) took the longest time of 21 minutes for the entire process, while it took 19 and 14 minutes for 50 and 80 oC, respectively. Though system air temperature and humidity varied along the dryer height, but no major difference was observed between the middle and top of the drier, indicating homogenous mixing among the mediums. Whereby the variables are not a function of space, unlike the usually used thin layers model. Air velocity shared a direct relationship with the rate change of system air temperature and humidity. It was also realized that the particle size distribution did affect the changes in the system environment. During the drying process, WG experience both dehydration and absorption. The rate of decrease was larger than the rate of increase of both MC and Aw of wheat germ. With the water activity controlled drying profile having a higher rate of decrease of MC and Aw than the time controlled drying. The trend of decrease in MC and Aw were able to be fitted using quadratic and exponential decay equations, with the prior being a better fit. While linear equation was used to fit the rate of increase. In terms of modeling, the proposed set of ordinary differential mass and energy balance model was able to fit well with the experimental data, especially in terms of the changes in MC. It was also able to predict the change in wheat germ temperature, which is not physically possible to be measured during the experiment. Understanding of the drying process is now made easier by just changing the variables in the model to obtain graphical presentation of its effects on the system. Such advantages not only enable the optimization of systems but also the prevention any undesirable reactions to occur, such as product degradation.

碩士
大同工學院
化學工程研究所
87
The drying of sewage sludge from CPT (Chinese Picture Tube Co.) was experimentally studied in a batch fluidized bed. Experiments were carried out in a 90mm I.D., 1.36m in height laboratory-scale fluidized bed to visualize the effects of superficial air velocity (1.18~1.35 Umf), inlet air temperature (30~60oC), bed temperature (50~80oC), initial moisture content of sludge (16.5~42.8%), weight ratio of glass beads to sludge (12~20) and particle sizes of sewage sludge (0.336~0.503 mm) on the drying characteristics. In this study, sewage sludge was fed to a fluidized bed with coarse particles being fluidized by hot inlet air, then the time variations of humidity and temperature of inlet and outlet air were measured under different operating conditions. The experimental results indicate that the maximum drying rate increases with increasing of superficial air velocity, inlet air temperature, bed temperature, weight ratio of glass beads to sludge but decreases with increasing the particle sizes. The empirical correlation for the maximum drying rate is proposed to fit the experimental data with a correlation coefficient of 0.95 and standard error of estimate of 0.18.

碩士
大同大學
化學工程研究所
90
The drying characteristics of sewage sludge from CPT (Chinese Picture Tube Co.) were experimentally studied in a continuous fluidized bed. Experiments were carried out in a 90mm I.D., 1.3m in height laboratory-scale fluidized bed to visualize the effects of superficial air velocity (1.13~1.46Umf), inlet air temperature (30~60oC), bed temperature (30~60oC), feeding rate of sewage sludge (0.83~1.33g/s) and static bed height (130~190 mm). Sewage sludge was continuously fed to a fluidized bed with glass beads being fluidized by hot inlet air, then the time variations of humidity and temperature of inlet and outlet air were measured under different operating conditions. The experimental results indicate that the drying degree increases with increasing superficial air velocity, inlet air temperature, bed temperature and static bed height, but with decreasing feeding rate of sewage sludge. The performance of the continuous fluidized bed dryer can be predicted from continuous dryer kinetics and the residence time distribution of exited sludge. The calculated outlet moisture contents are in agreement with the experimental data within 15% in this study.

博士
輔仁大學
食品營養博士學位學程
107
Wheat germ (WG) is a precious by-product from wheat milling process, natural and source. The main factor to determine the storage quality of WG is water activity, which is directly related to the moisture content (MC) of WG. Appropriate drying can reduce the lipid hydrolysis and enzymatic oxidation and consequently lower the rancidity and extend the shelf life of WG. Meantime, drying is one of the effective methods for material stabilization. Fluidized bed drying (FBD) is one of the technologies to attain this goal. Its efficiency depends on the size of fluidized bed, operation conditions (heating temperature and time: time-temperature history), material loading and air humidity and temperature. The objective of this research were to develop the engineering model for analysis the dehydration and condensation during WG drying in the FBD in order to reduce the trial and error, and to evaluate the energy efficiency of different time-temperature combination and loading during WG drying. The optimization of WG drying was based on the experimental data and simulation results. The drying process of WG was divided into four stages: preheating, loading, heating and cooling stage in fluidized bed system. The methods used in this thesis were divided into two parts: experimental measurement and numerical simulation. The air temperature, water activity and moisture content of WG during drying were measured. A mathematical model coupling with the macro-heat transfer model and the bubble model were developed to simulate the dehydration and condensation phenomena during WG drying in the FBD. From the results of the experimental and theoretical studies, a mathematical model coupling with the macro-heat transfer model and the bubble model was developed to simulate the dehydration and condensation phenomena during WG drying in FBD. The thermal input of the drying process with short heating time approach was one-third of that of the drying process with traditional heating approach. All time-temperature combinations could dry the WG to the target temperature of 45 °C and water activity of 0.3 ±0.1. The WG dehydration and condensation could also be evaluated by the dehydration flux and the condensation flux, respectively. A linear relation was obtained between WG loading and heating time. An optimization condition of WG drying process had been successfully applied for an industrial-scale FBD. Meantime, with the optimization condition and the industrial-scale FBD operation lead to the development of a new design of FBD.

MSc (Eng), Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2011
Most of the remaining coalfields in South Africa are found in arid areas where process water is scarce and given the need to fully exploit all the coal reserves in the country, this presents a great challenge to the coal processing industry. Hence, the need to consider the implementation of dry coal beneficiation methods as the industry cannot continue relying on the conventional wet processing methods such as heavy medium separation. Dry coal beneficiation with an air dense-medium fluidized bed is one of the dry coal processing methods that have proved to be an efficient separation method with separation efficiencies comparable those of the wet heavy medium separation process. Although the applications of the fluidized bed dry coal separator have been done successfully on an industrial scale, the process has been characterized by relatively poor (Ecart Probable Moyen), Ep values owing to complex hydrodynamics of these systems. Hence, the main objectives of this study is to develop a sound understanding of the key process parameters which govern the kinetics of coal and shale separation in an air fluidized bed focusing on the effect of the particle size, shape and density on the performance of the fluidized separator as well as developing a simple rise/settling velocity empirical model which can be used to predict the quality of separation. As part of this study, a (40 x 40x 60) cm air fluidized bed was designed and constructed for the laboratory tests. A relatively uniform and stable average bed density of 1.64 with STDEV < 0.01 g/cm3 was achieved using a mixture of silica and magnetite as the fluidizing media. Different particle size ranges which varied from (+9.5 -16mm), (+16 -22mm), (+22 -31.5mm) and (+37 -53mm) were used for the detailed separation tests. In order to investigate the effect of the particle shape, only three different particle shapes were used namely blockish (+16 -22mm Blk), flat (+16 -22mm FB) and sharp pointed prism particles (+16 – 22mm SR).Different techniques were developed for measuring the rise and settling velocities of the particles in the bed. The Klima and Luckie partition model (1989) was used to analyze the partition data for the different particles and high R2 values ranging from (0.9210 - 0.9992) were recorded. Average Ep iii values as low as 0.05 were recorded for the separation of (+37 -53mm) and (+22 -31.5mm) particles under steady state conditions with minimum fluctuation of the cut density. On the other hand, the separation of the (+16 -22mm) and (+9.5 – 16mm) particles was characterized by relatively high average Ep values of 0.07 and 0.11 respectively. However the continuous fluctuation or shift of the cut density for the (+9.5 -16mm) made it difficult to efficiently separate the particles. Although, particle shape is a difficult parameter to control, the different separation trends that were observed for the (+16 -22mm) particles of different shapes indicate that particle shape has got a significant effect on the separation performance of the particles in the air fluidized bed. A simple empirical model which can be used to predict the rise/settling velocities or respective positions of the different particles in the air fluidized bed was developed based on the Stokes’ law. The proposed empirical model fitted the rise/settling data for the different particle size ranges very well with R2 values varying from 0.8672 to 0.9935. Validation of the empirical model indicate that the model can be used to accurately predict the rise/settling velocities or respective positions for all the other particles sizes ranges except for the (+9.5 – 16mm) particles where a relatively high average % error of (21.37%) was recorded. The (+37 -53mm) and (+22 -31.5mm) particles separated faster and more efficiently than the (+16 -22mm) and (+9.5 -16mm) particles. However, the separation efficiency of the particles can be further improved by using deeper beds (bed height > 40cm) with relatively uniform and stable bed densities. Prescreening of the coal particles into relatively narrow ranges is important in the optimization of dry coal beneficiation using an air fluidized bed since different optimum operating conditions are required for the efficient separation of the different particle size ranges and shapes. The accuracy and the practical applicability of the proposed empirical model can be further improved by carrying out some detailed rise/settling tests using more accurate and precise equipment such as the gamma camera to track the motion of the particles in the fluidized bed as well as measuring the actual bed viscosity and incorporate it in the model.

碩士
建國科技大學
機械工程系暨製造科技研究所
100
This study established a rotating gas-solid fluidized bed equipment to investigate the flow behaviors and drying efficiency of rotating granular powders. A high speed camera system is used to observe the complex flow behaviors due to the centrifugal force, the fluid drag force and the interaction forces between particles. The glass beads with different sizes are used as the granules in the experiment. The experimental parameters include the particle size, the rotation speed and the superficial gas velocity. This study is divided into two stages: firstly, the flow behaviors of rotating fluidized bed with mono-disperse and binary mixtures are performed to examine the relationship between pressure drop and critical fluidization velocity. The experimental results are compared with the theoretical value of Ergun equation. Secondly, the drying efficiency of wet particles is performed with different rotating conditions. The experimental results show that the pressure drop and critical fluidization velocity increased with the particle size and the rotating speed for both mono-disperse and binary mixtures. In the cases of binary mixtures, the pressure drop and critical fluidization velocity decreased with the concentration of small particles. The outlet temperature drop period decreased with the increase of rotating speed for both mono-disperse and binary mixtures. The outlet temperature drop period decreased with the decrease of concentration of small particles for the cases of binary mixtures.

碩士
輔仁大學
食品科學系碩士班
107
Wheat germ, the most nutritious part of wheat, is rich in unsaturated fatty acids, protein, pantothenic acid, and vitamin E. Wheat germ contains lipase and lipoxygenase, their activities are therefore necessary to be inhibited through roasting and drying treatments to prevent hydrolysis and oxidation of fatty acids. However, the thermal treatment may lead to nutrients losses. Previous studies showed that the enzyme activity in wheat germ can be effectively inhibited by fluidized-bed drying, thus prevented fatty acid rancidity and extended wheat germ shelf life. Therefore, the purpose of this study is to compare the colors, functional components and nutrient contents of wheat germ by traditional roasting and fluidized-bed drying. For the traditional roasting, a multi-functional stir frying machine was used to roast wheat germ in a condition of 220°C for 30 minutes and then 170°C for 30 minutes. For the fluidized-bed drying, the wheat germ is dried either at 80°C for 4 minutes or 120°C for 1 minute. Results showed that the browning reaction was happened in roasted wheat germ that color changed obviously, and retained the most amounts of total phenolics, total flavonoids and vitamin E. The highest vitamin B1 content was observed in the 80°C fluidized-bed dried wheat germ, however, the 120°C fluidized-bed dried wheat germ showed the best trolox equivalent antioxidant capacity (TEAC). The total dietary fiber was not significantly affected by all three thermal treatments, but increased in the percentage of soluble dietary fiber. In conclusion, the wheat germ processed by 80°C fluidized-bed drying and traditional roasting has a potential to become a health food and nutritional supplement.

碩士
輔仁大學
食品科學系碩士班
105
Wheat germ (WG) is a by-product obtained from wheat milling and it contains highly concentrated nutrients. Due to large amount of unsaturated fatty acid and the presence of highly activated lipolytic enzymes, including lipase (LA) and lipoxygenase (LOX), WG products can easily turn into rancid flavor and shorten its short shelf-life. In the fluidized-bed drying process, the solid particles behave like a fluid due to air blowing and vigorously mix with the uniform and hot drying air. As a result, the drying time is shortened due to intensive heat and mass transfer. The objective of this study was to investigate the effect of water activity-controlled fluidized-bed drying on the retardation of lipid hydrolysis and oxidation of WG. The raw WG of 2 kg was dried with a vertical batch-type fluidized bed facility with following conditions, inlet air temperature of 50, 80 and 120 oC, inlet air velocity of 1.21 m/s and 3.62 m/s. The experiment was designed to obtain a final product at around 40 oC and water activity at 0.3 ± 0.1. Changes in the color, moisture content, water activity, enzyme activity and lipid stability of dried WG during storage (0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12 weeks) were observed. Results showed that the lightness of WG was lower, the redness and yellowness were higher when the drying temperature was increased. Besides, the moisture content, water activity and the activity of LA and LOX of WG were reduced after fluidized-bed drying process.The enzyme activity in WG dried at 80 oC and 120 oC was lower than that in WG dried at 50 oC. The moisture content and water activity of WG were in the range of 5.5-8.5% and 0.25-0.48, respectively, during 12 weeks of storage. The LA activity in WG increased slowly during the first 6 weeks of storage and reached a plateau for another 6 weeks, whereas the LOX activity increased slowly during the first 2 weeks of storage and decreased after 3 weeks. As compared to the raw WG, the free fatty acid content, peroxide value and thiobarbituric acid value of dried WG was low during 12 weeks of storage. The inlet air velocity of fluidized-bed drying process affected the results significantly under the same drying temperature, except for the LOX activity. In conclusion, WG dried in the fluidized-bed drying facility with 3.62 m/s at 80 oC had the best storage stability. Therefore, the water activity of WG could be controlled at 0.3 by using the fluidized-bed drying facility within a short period of time. The above treatment could effectively inhibit the activity of LA and LOX leading to the retardation of lipid oxidation and extending the shelf-life of WG.

碩士
長庚大學
化工與材料工程研究所
97
A countercurrent continuous fluidized bed system performs different flow regimes at different operating conditions. This thesis focused on the investigation of the effect of the hole arrangement on the plate on the bed flow regimes and the application of this system to porous particles drying. The results showed that with the same plate hole opening ratio、different plate hole arrangement affected the particles flow regimes. The triangular hole arrangement required higher gas velocities and/or solid feeding rates to reach the same stable flow regimes when comparing to the equilateral hole arrangement. With the same hole arrangement、the operation window increased with the increasing of the plate opening ratio and their location in the feeding rate versus gas velocity figure moved upwards. When porous zeolite particles were dried in the countercurrent fluidized bed、the result showed that the drying rate increased with the increasing of the drying temperature and gas velocity. The drying rate was higher when using the equilateral hole arrangement plate compared to that using the triangular hole arrangement plate at similar operating conditions. This was due to the fact that longer particles resident times were obtained in the countercurrent fluidized with equilateral hole arrangement plate.