Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-04-12T16:58:50Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Ulysses.pdf: 2292611 bytes, checksum: 94f0d93357c24023b30a73414786b32e (MD5) / Made available in DSpace on 2017-04-12T16:58:50Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Ulysses.pdf: 2292611 bytes, checksum: 94f0d93357c24023b30a73414786b32e (MD5) Previous issue date: 2016-01-29 / CAPES / O processo de obtenção do gesso beta, que consiste na desidratação do minério da gipsita a uma temperatura entre 125 °C e 160°C, é realizado em fornos rotativos através de queima direta ou indireta. Os principais combustíveis utilizados neste processo no Polo Gesseiro do Araripe são a lenha, o coque de petróleo, o óleo BPF e gás natural. Esta dissertação estuda a modelagem matemática de um sistema de calcinação com aquecimento indireto utilizando dois combustíveis sólidos diferentes: a lenha e o coque de petróleo. A modelagem é feita por meio do Método dos Volumes Finitos em um modelo bidimensional de coordenadas cilíndricas. Através da simulação numérica é possível prever o perfil de temperatura em uma seção transversal do forno, tal como suas taxas de aquecimento. São observadas as influências de parâmetros como vazão mássica do combustível, percentual de excesso de ar na combustão e teor de umidade da lenha. Também é realizada uma comparação entre os processos utilizando a lenha e o coque com relação ao custo e à emissão de dióxido de enxofre (SO2). / The process of obtaining the beta plaster, which consists of dehydration of the gypsum ore under a temperature between 100°C and 160 °C, is performed in rotary kilns through direct or indirect burn. The main fuels utilized in this process at Araripe Gypsum District are firewood, petroleum coke, heavy fuel oil and natural gas. This dissertation studies the mathematical modeling of a calcination system with indirect heating using two different solid fuels: firewood and petroleum coke. The modeling is made by using the Finite Volume Method in a two-dimensional model of cylindrical coordinates. Through the simulation is possible to predict the temperature behavior in a cross section of the kiln, as well as its heating rates. It was analyzed the influence of parameter such as mass flow rate, percent excess combustion air and moisture content of the firewood. A comparison between the processes using firewood and coke is also conducted, concerning the cost and the sulfur dioxide (SO2) emission.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Lignocellulosic biomass use for obtaining biofuels has been showing itself with much more evidence during these past years through cellulosic ethanol and biooils, biogases and biochars. Aquatic plants of lignocellulosic basis, Eichhornia crassipes species, commonly known by water hyacinth, represent a major environmental problem due to their invasive nature and their high proliferation rate. In this work we evaluated the possibility of use this biomass source from pyrolysis in a rotary kilns reactor in three different temperatures. The results evidence that the major yield of the liquid fraction (bio-oil + acid extract) was obtained at 500 ºC (42.11%). For 400 ºC and 600 ºC, the biochar and biogas had major production, 37.78% and 42.36%, respectively. Bio-oils characterization by GC/MS produced in microscale allowed an investigation upon the scale-up phenomenon under the bio-oils composition. The results show that, in qualitative terms, the chemical composition of bio-oils was not changed, however, at semiquantitative aspect, show they are produced in distinguish relative percentages. The mainly chemical classes identified in biooils were: acids, alcohols, phenols and sugar derivatives. Bio-oils showed in average, 68% of calorific power of the fuels derived from petroleum, glimpsing enforcement on the energetic area. In the produced biochars, with yields between 37% and 26%, the increase on pyrolysis temperature has provided an increase upon carbon concentration, and a decreasing upon the hydrogen and oxygen concentrations, reflecting in high aromaticity of the materials. These materials ware tested in some aspects about the soils management, nutritional function and water retention. In view of this, the water hyacinth pyrolysis has associated sustainability concepts and green chemistry, putting concepts of renewable energetic sources together and glimpsing an environmental problems inhibition, to offer an alternative to the 2nd generation of bio-fuels production. / O uso de biomassas lignocelulósicas para a obtenção de biocombustíveis apresenta-se com muito mais evidência nos últimos anos através do etanol celulósico e de bio-óleos, biogás e biocarvão. As plantas aquáticas de base lignocelulósica da espécie Eichhornia crassipes, popularmente conhecida por aguapé, representam um grande problema ambiental devido ao seu caráter invasor e sua alta taxa de proliferação. Neste trabalho avaliou-se a possibilidade de aproveitamento dessa fonte de biomassa a partir do processo de pirólise em um reator cilindro rotativo em três diferentes temperaturas. Os resultados demonstraram que o maior rendimento da fração líquida (bio-óleo + extrato ácido) foi obtido a 500 ºC (42,11%). Para as temperaturas de 400 e 600 ºC, o biocarvão e o biogás tiveram maior produção, 37,78% e 42,36%, respectivamente. A caracterização por CG/EM dos bio-óleos produzidos em microescala permitiram investigar o efeito de scale-up sob a composição dos bio-óleos. Os resultados mostraram que em termos qualitativos, a composição química dos bio-óleos não foi alterada, no entanto, no aspecto semiquantitativo mostraram que são produzidos em percentuais relativos distintos. As principais classes químicas identificadas nos bio-óleos foram: ácidos, álcoois, fenóis e derivados de açúcares. Os bio-óleos apresentaram em média 68% do poder calorífico do combustível derivado de petróleo, vislumbrando uma aplicação na área energética. Nos biocarvões produzidos, com rendimento variando de 37% a 26%, o aumento da temperatura de pirólise proporcionou um aumento na concentração de C, e uma diminuição nas concentrações de H e O, refletindo em maior aromaticidade dos materiais. Estes materiais foram testados sob alguns aspectos quanto ao manejo de solos, função nutricional e retenção de água. À vista disto, a pirólise de aguapé relacionou conceitos de sustentabilidade e química verde, unindo o conceito de fontes de energias renováveis com a inibição de problemas de cunho ambientais, ao oferecer uma biomassa alternativa para a produção de biocombustíveis de 2ª geração.

Ce travail porte sur l'étude de fours tournants équipés de releveurs. Ce sont des contacteurs gaz/solide largement répandus dans de nombreux secteurs industriels mettant en oeuvre des solides divisés. Cependant en raison d'une faible connaissance du fonctionnement de ces équipements notamment en matière d'écoulement ou de transfert thermique, leur utilisation repose encore beaucoup sur le savoir faire des opérateurs acquis avec le temps. Ainsi ce travail vise à fournir aux ingénieurs des outils de connaissance et d'extrapolation pour les accompagner dans les phases de dimensionnement, mais aussi d'optimisation de procédés existants, en particulier pour des fours tournants en chauffage indirect et équipés de releveurs. La première partie de cette étude porte sur l'influence des conditions opératoires sur l'hydrodynamique des solides divisés de forme et taille différentes. Pour ce faire, des procédures expérimentales pour la mesure de distribution des temps de séjours des particules solides ont été mises en oeuvres. Deux pilotes de four tournant ont été utilisés. Ces derniers ont un ratio longueur sur diamètre équivalent mais un ratio de taille de 2. L'hydrodynamique des fours a été caractérisée quantitativement à partir des résultats expérimentaux en terme de temps de séjour des solides, taux de remplissage du four ainsi que de la dispersion axiale des particules. Ces derniers ont été modélisés par analyse dimensionnelle dans un souci de généralité en prenant en compte la présence d'éléments internes (releveurs, grille) ou diaphragmes en sortie, mais aussi des paramètres opératoires tels que la vitesse de rotation du tube, son inclinaison ou le débit des particules solides. La seconde partie de cette étude s'intéresse aux processus de transfert thermique dans les fours tournants en chauffage indirect et équipés de releveurs. Cette étude repose sur la mesure des profils de température à la paroi, dans la phase gazeuse et le lit de particules solides. L'analyse de ces profils de température se focalise sur la détermination des coefficients de transfert de chaleur entre la paroi et le lit de solides d'une part, et entre la paroi et le gaz d'autre part. Une méthode d'analyse globale de système mince et un bilan global intégrant la puissance fournie pour la chauffe sont utilisés pour la détermination de ces coefficients de transfert. Les résultats obtenus permettent d'une part de mettre en évidence l'effet des releveurs ainsi que l'influence des paramètres opératoires sur ces coefficients de transfert de chaleur et d'autre part d'établir par analyse dimensionnelle des modèles pour ces derniers. Enfin, ce travail se termine par la mise en place d'un modèle dynamique simplifié de four tournant en chauffage indirect permettant la détermination des profils de température le long du four et pouvant être facilement adapté à divers procédés. / The present work addresses a fundamental study on flighted rotary kilns. They are gas-solid reactors, used in a variety of industries to process heterogeneous media. However, operating these kilns mainly relies on the know-how of operators due to insufficient fundamental understanding. The aim of this work is to provide engineers with relevant tools and models to assist in the design stage and the performance improvement of existing operating process units, in particular indirectly heated rotary kilns, inclined and equipped with lifters. In the first part, we studied the effects of operating parameters on the flow of materials of differing properties and shape. For this purpose, residence time distribution measurements were performed through experimental stimulus response tests. Two pilot-scale rotary kilns with similar length-to-diameter ratios, but a dimension ratio of about two were used in this study. We focused on the effects of lifter shape and configurations. The effects of the rotational speed, the kiln slope, the mass flow rate and the exit dam height were also analyzed. The flow of solids was quantitatively characterized primarily by the experimental mean residence time, hold-up, and axial dispersion coefficient. Using a dimensional analysis, models were established to predict the mean residence time, the filling degree and the axial dispersion coefficient, providing basic information on the kiln design, solid particle properties and operating conditions. In the second part, we studied the heat transfer mechanisms occurring in the flighted rotary kiln by measuring temperature profiles at the wall, the freeboard gas and the bulk of solids. Analysis of the temperature profiles focused on two main issues: assessment of the heat transfer coefficient between wall and gas, and assessment of the heat transfer coefficient between wall and solid particles. The lumped system analysis and a heat balance using the power supplied for the heating were applied to determine the experimental heat transfer coefficients. The effects of operating conditions and lifting flights were analyzed. Both heat transfer coefficients were then correlated through dimensional considerations. Lastly a global dynamic model mainly based on the models developed in this study can be used to determine wall, gas and bulk solids axial temperature profiles in an indirectly heated flighted rotary kiln. This global model needs to be completed with specific models related to a reaction so as to be used as a framework for the simulation of specific industrial rotary kilns.