La pyrolyse et la gazéification sont les deux procédés les plus prometteurs pour une valorisation thermique des déchets organiques solides en réponse aux objectifs énergétiques environnementaux actuels et futurs. Si pour la pyrolyse, les déchets traités sont aussi synthétiques (plastiques, composites) que naturels (biomasse), pour la gazéification c'est la biomasse qui est la matière première la plus rencontrée. Les travaux expérimentaux de cette thèse ont été réalisés dans deux types d'installations : une installation à échelle laboratoire (analyseur thermique : TG, ATD, EGA) et une installation à échelle pilote (nommée four « Aubry »). Les traitements thermiques ont été effectués dans les conditions spécifiques pour la pyrolyse (atmosphère d'azote) et la gazéification (vapeurs d'eau). Les matériaux testés ont été le polychloroprène, les composés de la biomasse (hémicellulose, lignine, cellulose), seuls où en mélange, ainsi qu'un bois naturel (le bouleau) et son « modèle » (mélange en proportions équivalents de ses constituants). Deux modèles cinétiques pour la pyrolyse du polychloroprène ont été choisis de littérature et testés. La différence primordiale entre les deux modèles est leur degré de complexité. Le premier est un modèle empirique simplifié, tandis que le deuxième, très détaillé, est un modèle radicalaire Le modèle cinétique utilisé pour modéliser le processus de pyrolyse de la cellulose, pris aussi de la littérature, a montré une concordance très bonne avec nos résultats expérimentaux. L'étude hôte de la gazéification à la vapeur d'eau a nécessité des modifications de nos installations expérimentales, tout particulièrement à l'échelle pilote, pour assurer une atmosphère confinée en vapeur d'eau. Les expériences réalisées en conditions expérimentales spécifiques ont données des résultats excellents pour la composition finale du gaz de synthèse. La simulation, à l'échelle pilote, de la gazéification a été obtenue par adaptation d'un modèle existant, à la réalisation de nos conditions opératoires, prenant en compte les transferts matières et basé sur l'évolution de la porosité d'une particule sphérique équivalente. Le modèle a montré une concordance raisonnable avec nos données expérimentales. La dernière partie de cette thèse présente une étude dans lequel on compare les analyses thermiques pour les constituants purs, un modèle de bois et un bois naturel afin d'établir les interactions possibles entre ces composants lors de la dégradation thermique du bois naturel. Les résultats ont montré que pour les mélanges cellulose-lignine et lignine-hémicellulose, le premier composé inhibe la dégradation du dernier tandis que, pour les mélanges cellulose-hémicellulose, cet effet se manifeste à l'inverse. Tous les modèles testés et les résultats enregistrés dans cette thèse représentent des instruments très utiles pour l'aide au dimensionnement des installations de pyrolyse à échelle laboratoire ainsi que pour des installations de gazéification à la vapeur d'eau à échelle pilote. / The pyrolysis and gasification are the most actual techniques used for valorization of organic wastes. If for pyrolysis the raw materials are both synthetic (plastics) and natural (biomass), in the case of gasification mainly the biomass is used. The experiments presented in this thesis were carried out in two type of plants: a laboratory scale plant (thermal analyses: TGA, DTA, EGA) and a pilot scale plant (so-called “Aubry” furnace). The thermal treatments implemented both the conditions of pyrolysis (nitrogen atmosphere) and gasification (water vapors). The materials tested in the experimental part were: polychloroprene, biomass constituents (hemicelluloses, lignin and cellulose), alones and in mixture, and a natural wood (the birch) with it's “model” (a mixture of it's components in different proportions). For the polychloroprene pyrolysis, two kinetic models chosen from the published literature were tested. The difference in the two models is given by their degree of complexity. The first one was a simplified empirical model. The second one was a free-radical model. For the cellulose pyrolysis was also tested a model proposed in the literature and the model showed a good accuracy in representing our experimental data. The study of gasification at pilot scale needed an appropriate modification of the experimental set-up to create a saturated atmosphere in water vapor inside the Aubry furnace. The experimental work concerning the gasification followed a specific protocol and gave excellent results for the syngas composition. A gasification mathematical model for pilot scale was proposed and tested. This model, based on the evolution of equivalent spherical particles porosity, take supplementary into account the mass transfer. The results given by the last model were in reasonable agreement with our experimental results. The last part of this thesis presents a comparative study of the thermal analyses of pure biomass components, of a wood model and also of a natural wood. The goal is to identify the interactions that could take place between these compounds during the thermal degradation of the natural wood. Our results showed that for the mixtures cellulose-lignin and lignin-hemicelluloses the first compound inhibits the second one. For the mixtures cellulose-hemicelluloses this effect is inverse. All the kinetic models tested in this thesis are useful tools for dimensioning laboratory scale pyrolysis plants and pilot scale set-up for water vapors gasification.

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