Ce travail traite du rôle des interactions entre les composés inorganiques (cendres) et les matériaux du lit pendant la gazéification de miscanthus en lit fluidisé. Les objectifs étaient :-1) de décrire la transformation des inorganiques à haute température ; -2) de comprendre leur rôle dans l’agglomération ; et -3) de proposer des recommandations. Les principaux éléments inorganiques présents dans le miscanthus sont K, Si Ca, Mg, P, S et Cl. Les cendres sont constituées de silice, de carbonates et de sels. Les carbonates et les sels se décomposent et se volatilisent à 700 °C. Les Ca et Mg silicates sont les phases solides majoritaires à haute température. La phase liquide est constituée de SiO2, K2O, CaO et MgO quel que soit la nature de l’atmosphère. Les résultats expérimentaux ont été comparés aux calculs thermodynamiques. Il apparait que les bases de données FToxid et FTsalt peuvent être utilisées pour prévoir les tendances des transformations de phases en température. Les interactions entre les cendres et les matériaux du lit ont été étudiées en conditions statiques et dynamiques. Les conclusions sont les suivantes : -1) la mouillabilité des cendres sur les matériaux du lit est un paramètre clé dans l’agglomération ; -2) l’adhésion augmente dans l’ordre suivant : silice → olivine → olivine calcinée ; -3) il y a peu de différences en atmosphère oxydante ou réductrice -4) la présence de deux liquides immiscibles est observée en atmosphère réductrice. Des traces de sulfures et de résidus carbonés ont aussi été observées. Des expériences ont été effectuées à haute température, en conditions dynamiques, avec un dispositif expérimental de laboratoire et avec un pilote de gazéification à lit fluidisé. En condition dynamique, la température est un paramètre très important. Le lavage de la biomasse et l’ajout de kaolin permettent de limiter l’agglomération. Dans le gazéifieur pilote, les gros agglomérats se retrouvent préférentiellement au niveau de la grille et limite la fluidisation. Les teneurs en Fe, Cr et Al de la phase liquide sont plus importantes que celles observées en laboratoire. / This work studies the role of inorganics in ash-bed material interaction during thermal conversion of miscanthus in fluidized bed. The objectives were (1) to describe the transformation of inorganics at high temperature, (2) to reveal their role in the agglomeration and (3) to provide recommendations for miscanthus gasification in fluidized bed. The main ash forming elements in miscanthus are K, Si, Ca, Mg, P, S and Cl. The ashes are composed of silica, carbonates and salts. The carbonates and salts decompose and volatilize at 700ºC, at elevated temperature the dominant solid phases are Ca and Mg silicates. The liquid phase is composed of SiO2, K2O, CaO, MgO regardless of the atmosphere. The accuracy of thermodynamic prediction tool was evaluated with the experimental results. In conclusion, FToxid and FTsalt databases can be used to follow the trends of the main phase transformations at high temperature. The ash-bed interaction was studied under static and dynamic conditions. We found that the wetting of bed material by molten ashes is the key parameter of the agglomeration. The adhesion of particles increases in the order of sand, olivine, calcined olivine. There is no significant difference in the agglomeration mechanism in oxidizing or reductive atmosphere. However, in reductive atmosphere, two immiscible liquid phases can occur and the presence of unburnt char and traces of sulphides was also observed. The ash-bed material interaction was studied under dynamic conditions in a bench scale device and in a fluidized bed gasifier pilot. The parametric investigation showed that the operating temperature has the most significant effect on the agglomeration ratio and the biomass pre washing or the addition of kaolin are the most effective tools to reduce agglomeration risks. During the trials in the gasification pilot the large agglomerates segregated on the grid accelerating the defluidization. Compared to the laboratory tests, the liquid phase is enriched in Fe, Cr and Al.

This thesis is an experimental study of the fluidization of binary mixture in particulate flows. A fluidized bed with two distributors was built with water being used as carrying fluid. Three types of solid particles of nylon, glass and aluminum of the same size and different densities are used in the experiments. The wall effect on a single particle fluidization, the fluidization of binary mixture of large density difference (nylon and aluminum of density ratio of 0.42), and the fluidization of binary mixture of close density (glass and aluminum with density ratio of 0.91) were investigated. Also, the effect of distributors on mono-disperse and bi-disperse particle fluidization was investigated. Results show that the presence of narrow walls reduces the minimum fluidization velocity for a single particle by as much as nearly 40%. Also, in the case of binary mixture of close density particles, uniform mixing was easily achieved and no segregation was observed, but in the case of large density difference particles, there exists significant segregation and separation. At high velocity, the uniform distributor behaves like a transport bed. To achieve a full bed in the single jet, it requires 1.5 times velocity of the uniform distributor. This behavior determines their application in the industries.

Orientadores: Araí Augusta Bernárdez Pécora, Emerson dos Reis / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T13:04:25Z (GMT). No. of bitstreams: 1 RuedaOrdonez_DiegoAndres_M.pdf: 19506541 bytes, checksum: 0bbc753dfedabd5800a9c9bd05c71077 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho, foi utilizada uma metodologia para a análise dos sinais de flutuações de pressão visando estudar a fluidização e o fenômeno da segregação em leitos fluidizados contendo misturas binárias de partículas de diferentes tamanhos e massas específicas. As medidas foram feitas para caracterizar o comportamento fluidodinâmico do leito fluidizado contendo misturas binárias e encontrar as velocidades inerentes ao fenômeno da segregação. Para tanto, primeiramente foram estudados os comportamentos de cada material isolado para posterior comparação com o comportamento observado para as misturas contendo tais materiais.Três tipos de sólidos particulados foram utilizados neste trabalho: microesferas de plástico (diâmetro médio de Sauter de 971 µm) e microesferas de vidro (diâmetros médios de Sauter de 462 e 959 µm).O sistema experimental utilizado consiste de uma coluna, de 0,1 m de diâmetro e 2,5 m de altura, equipada com um distribuidor de gás tipo placa porosa e possuindo seções de vidro,acrílico e aço carbono intercaladas, o que permitiu acompanhar visualmente o processo, e adquirir imagens por meio de uma câmera fotográfica. Medidas de flutuações de pressão foram feitas em diferentes velocidades superficiais do gás para cada material ou mistura estudados. Os sinais de pressão foram medidos em três pontos na coluna do leito, sendo um no plenum e dois na coluna, situado a 0,035 e a 0,115 m acima da placa distribuidora.Em todos os testes a altura do leito foi mantida fixa em 0,150 m. As flutuações de pressão foram analisadas no domínio do tempo e no domínio da frequência aplicando a transformada rápida de Fourier (FFT) o que permitiu diferenciar o comportamento dinâmico das misturas em cada velocidade superficial do gás estudada.Os resultados permitiram identificar regiões com diferentes comportamentos fluidodinâmicos e velocidades inerentes ao processo de segregação como as velocidades de fluidização inicial, fluidização completa, de segregação e de mistura completa. Este trabalho procura contribuir para melhorar o entendimento sobre a fluidização de misturas binárias e sobre o fenômeno de segregação normalmente presente em tais sistemas / Abstract: A methodology for analysis of pressure fluctuations signals was used, in the present work, to study the ?uidizing and segregation phenomena in fluidized beds containing granular binary mixtures with different sizes and densities. Pressure measurements have been made to characterize the dynamic behavior of fluidized beds and to find the velocities involved in the segregation phenomena. The analysis of each single studied material was made before analyzing of the mixtures containing such materials. Three types of solid particles were used in this work: plastic microspheres (971 µm Sauter mean diameter) and glass microspheres (462 and 959 µm Sauter mean diameters). The experimental system presents a column, 0.1m diameter and 2.5 m height, equipped with a porous plate gas distributor. The column was made by glass, acrylic and carbon-steel sections to allow visual observations of the process and acquiring images by a camera. Measurements of pressure fluctuations were made in different gas superficial velocities for each studied material or mixture. The pressure signals were measured at three points in the column: one at plenum and two above the distributor plate, at 0.035 and 0.115 m above the distributor plate. The height of the bed material was fixed in 0.15 m regarding all performed tests. Pressure fluctuations were analyzed on the time domain and on the frequency domain using the fast Fourier transform (FFT) which allows differentiating the dynamic behavior of the mixtures in each superficial gas velocity studied. The results allowed the identification of regions with different fluid dynamic behaviors as well as the determination of gas velocities inherent to the segregation process as the initial fluidization, complete fluidization, segregation and complete mixing velocities. This paper aims to contribute on understanding the fluidization process of binary mixtures and on the phenomenon of segregation normally present in such systems / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Orientador: Milton Dall'Aglio Sobrinho / Banca: Tsunao Matsumoto / Banca: Gilson Arimura Arima / Resumo: O reator aeróbio de leito fluidizado com circulação apresenta características que permitem efetuar o tratamento em apenas uma etapa. O uso deste reator torna-se atraente devido à possibilidade de mantê-lo com uma alta concentração de biomassa ativa, propiciando seu porte compacto, conseqüência do reduzido período de detenção hidráulica. A eficiência do biofilme no tratamento depende das condições hidrodinâmicas do reator, uma vez que sua espessura pode ser alterada de acordo com a velocidade de circulação, e a transferência de oxigênio através de suas camadas depende da vazão de ar injetada no sistema. O trabalho propôs-se a investigar a influência da relação entre diâmetros dos tubos concêntricos em quatro configurações, mantendo o diâmetro externo constante e igual a 250 mm e alterando o diâmetro interno entre 100, 125, 150 e 200 mm, proporcionando relações Ae/Ai iguais a 5,25; 3,00; 1,78 e; 0,56, respectivamente. O tubo interno possui 2,22 m e é posicionado 0,05m acima do fundo do reator. A altura estática da coluna de fluido foi 2,35 m. Os ensaios hidrodinâmicos - velocidade do líquido, fração volumétrica de ar, tempo de mistura - e os de transferência de oxigênio foram realizados para vazões de ar até 2500 l/h em meio bifásico e em meio trifásico com concentrações de areia iguais a 30, 70, 100 e 150 g/l. O diâmetro interno de 125 mm foi o mais eficiente na indução de velocidade de circulação do líquido. A fração volumétrica de ar aumentou com o aumento do diâmetro interno para mesmas velocidades superficiais de ar, com exceção do menor diâmetro, o qual apresentou comportamento diferenciado dos demais. Os reator com diâmetro interno de 150 mm apresentou maiores valores de KLa para as mesmas vazões de ar. Observou-se que a adição de sólidos causou um decréscimo da velocidade do líquido e da fração... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Aerobic internal-loop airlift reactor has some characteristics that allow wastewater treatment in a single stage. The attractive to use this kind of reactor is mainly because of its capacity of maintaining a high active biomass concentration into it, which induces its small structure, in a consequence of its small hydraulic detention time. The biofilm efficiency in the treatment depends on reactor's hydrodynamic conditions. The structure of the biofilm and the oxygen transfer into its layers is affected by the liquid velocity induced by the air flow rate. This work proposed an investigation about the influence of the diameter of the concentric tubes, using four geometric configurations. The model had a 250 mm external tube and the inner draft tube with diameters of 100, 125, 150 and 200 mm, which means AD/AR equals to 5.25, 3.00, 1.78 and 0.56, respectively. The draft tube's height was 2,22 m and was positioned 0,05 m above the bottom of the reactor. The static fluid height was 2,35 m. The hydrodynamic tests - liquid velocities, gas hold up, mixture time - and the oxygen transfer tests were conducted for two and three-phase systems, with variable air flow rate up to 2500 l/h. The solid phase concentrations used were 30, 70, 100 and 150 g/l. The 125 mm reactor was the most efficient in inducing the liquid circulation velocity. The gas hold up increased with the increasing of the draft tube diameter, for same superficial gas velocities, excepting the 100 mm, which showed a different behavior. The 150 mm reactor presented the highest values for KLa for the same air rate. It was noticed that the solids addiction decreased the liquid velocity, gas hold up and oxygen transfer. Hydrodynamics equations found in literature showed a limited applicability, evidencing the necessity of relations capable to reach the most different configuration for this kind of reactor. A mass transfer mathematic...(Complete abstract click electronic acces below) / Mestre

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22428号 / 工博第4689号 / 新制||工||1732(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 酒井 伸一, 教授 田中 宏明, 准教授 平井 康宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The aim of this thesis is to design a desulphurization device for the fluid boiler. In the fluid boiler, fuel with extremely high sulphur content is burnt and the combustion products are not desulphurized to the required level, therefore it is necessary to build a desulphurization device. The thesis consists of two parts – theoretical and practical. In the theoretical part I stated the emission limits of sulphur dioxide, elaborated possible desulphurization methods and described the sorbets suitable for desulphurization. In the practical part I chose a dry desulphurization method with fluid reactor, to which a dry sorbent on the basis of lime hydrate is dosed. For the required parameters, I designed the whole desulphurization equipment including cloth filters, all necessary silos and major components. It is a design proposal with a layout and a spatial model.

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Producing gasoline-type fuels from lignocellulosic biomass has two advantages over producing alcohol-type fuels from plant sugars: gasoline has superior fuel characteristics and plant lignin/cellulose does not compete with human food supplies. A promising technology for converting lignocellulose to fuel is catalytic fast pyrolysis (CFP). The process involves injecting finely ground biomass into a fluidized bed reactor (FBR) at high temperatures, which reduce the biomass to gases that react inside the catalyst particles. This entails complex hydrodynamics to efficiently mix a stream of biomass into a catalyst bed that is fluidized by a separate stream of inert gas. Understanding the hydrodynamics is complicated by the fact that the entire process occurs inside a heavily insulated, opaque, reactor vessel. Numerical simulations offer a promising approach to understanding, predicting, and optimizing hydrodynamic mixing in a CFP biomass reactor. The purpose of this research is to understand the simulation techniques and statistical measures appropriate for quantifying mixing in a CFP biomass reactor. The methodology is validated against the canonical configuration of a non-reacting, single-inlet fluidized bed. A new finding is that the minimum bubbling velocity may be predicted by a significant increase in temporal variance of the pressure drop. The methodology is then applied to a non-canonical FBR in which biomass is injected into the catalyst bed via a vertical center tube. Since no hydrodynamic mixing data exist from laboratory experiments, mixing is inferred from the aromatics yield from the laboratory reactor. Flow configurations with which simulations demonstrate the best mixing have the highest aromatic yields in the experiments. The simulations indicate that when the bed is in the bubbling regime, the gasified biomass from the center tube is efficiently mixed radially throughout the catalyst bed. If the flow rate of inert gas is insufficient to bubble the bed, then the gasified biomass exits the center tube, reverses direction, and flows upward along the tube's outside wall. Provided the bed is bubbling due to the inert gas stream, the upper limit on the flow through the center tube, and thus the aromatic yield potential, has yet to be determined.