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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
401

Produção de hidrogênio a partir da manipueira em reator anaeróbico de leito fluidificado / Hydrogen production from manipueira in anaerobic fluidized bed reactor

Amorim, Norma Candida dos Santos 21 June 2012 (has links)
Hydrogen has been studying as an alternative energy source to replace fossil fuels. This is justified because, in its combustion is generating primarily water vapor and by its energy content is approximately 2.5 times greater than any fossil fuel. Besides these advantages, hydrogen can be produced from renewable sources, such as various types of industrial and domestic waste rich in carbohydrates. Thus, the purpose of this study was to evaluate the production of hydrogen from a substrate real, the manipueira (wastewater processing cassava), as carbon source in anaerobic fluidized bed reactor (AFBR) operated under a progressive increase in the organic loading rate (OLR). The support material for the adhesion of biomass has been expanded clay (2.8 to 3.35 mm) and the reactor was inoculated with anaerobic sludge thermal pretreatment. The reactor was operated for 164 days and gradually increasing the organic loading rate was obtained by maintaining a constant influent COD (4000 mg. L-1) throughout the operation of the reactor and varying the hydraulic retention time (HRT) of 8 to 1 hour. The production of hydrogen ranged from 0.20 to 2.04 L.h-1.L-1, when the HRT reduced from 8 h to 1 h. The yield had an increase from 0.31 to 1.91 mol H2.mol glucose-1 by reducing the HRT from 8 to 2 h. By lowering the HRT for 1 h, the yield was reduced, reaching a value of 1.20 mol H2.mol glucose-1. The soluble metabolites present during the operation of the reactor were acetic acid, butyric acid, propionic acid and ethanol. The microscopic analysis indicated the presence of bacilli, which are morphologies similar to species of the genus Clostridium sp. and Enterobacter sp., which are known as potential production of hydrogen in fermentation processes. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O hidrogênio vem sendo estudado como fonte alternativa de energia em substituição aos combustíveis fósseis. Isso porque, na sua combustão há geração principalmente de vapor de água e por seu conteúdo energético ser aproximadamente 2,5 vezes maior do que qualquer combustível fóssil. Além dessas vantagens, o hidrogênio pode ser produzido a partir de fontes renováveis, tais como os diversos tipos de resíduos industriais e domésticos ricos em carboidratos. Dessa forma, o objetivo da pesquisa foi avaliar a produção de hidrogênio a partir de um substrato real, a manipueira (água residuária do processamento da mandioca), como fonte de carbono em reator anaeróbio de leito fluidificado (RALF) operado sob aumento progressivo da taxa de carregamento orgânico (TCO). O material suporte para a aderência da biomassa foi argila expandida com diâmetro entre 2,8 3,35 mm e o reator foi inoculado com lodo anaeróbio pré-tratado termicamente. O reator foi operado por 164 dias e o aumento progressivo da taxa de carregamento orgânico foi realizado mantendo a DQO afluente constante (4000 mg. L-1) durante toda a operação do reator e variando o tempo de detenção hidráulica (TDH) de 8 horas até 1 hora. Foi constatado que a produção volumétrica de hidrogênio aumentou de 0,20 até 2,04 L.h-1.L-1, quando foi reduzido o TDH de 8 h para 1 h. E o rendimento sofreu um incremento de 0,31 até 1,91 mol H2.mol glicose-1, com a redução do TDH de 8 para 2 h. Ao reduzir o TDH para 1 h, o rendimento sofreu uma redução, atingindo o valor de 1,20 mol H2.mol glicose-1. Os metabólitos solúveis presentes durante a operação do reator foram o ácido acético, ácido butírico, ácido propiônico e etanol. As análises microscópicas indicaram a presença de bacilos, os quais são morfologias semelhantes às espécies dos gêneros Clostridium sp. e Enterobacter sp., que são conhecidas como potenciais produtoras de hidrogênio em processos fermentativos.
402

Hydrodynamic modeling of poly-solid reactive circulating fluidized beds : Application to Chemical Looping Combustion / Modélisation hydrodynamique de lits fluidisés circulants poly-solides réactifs : application à la combustion en boucle chimique

Nouyrigat, Nicolas 28 March 2012 (has links)
Une étude précise des écoulements gaz-particules poly-solides et réactifs rencontrés dans les lits fluidisés circulants (LFC) appliqués au procédé de Chemical Looping Combustion (CLC) est indispensable pour prédire un point de fonctionnement stable et comprendre l'influence de la réaction et de la polydispersion sur l'hydrodynamique des LFC. Dans ce but, des simulations avec le code NEPTUNE_CFD ont été confrontées aux expériences menées à l'Université Technologique de Compiègne par ALSTOM. Cette modélisation a été validée sur des LFC non réactifs mono-solides et poly-solides. L'influence des caractéristiques des particules et de la position des injecteurs sur l'entrainement de solide est étudiée. Un modèle de prise en compte de la production locale de gaz au cours de la réaction est présenté. L'étude locale de l'écoulement a permis de comprendre l'influence des collisions interparticulaire et de la production locale de gaz sur l'écoulement. Finalement, un point de fonctionnement a été proposé pour le pilote CLC en construction à Darmstadt. Ce travail a montré que NEPTUNE_CFD pouvait prédire l'hydrodynamique de LFC poly-solides à l'échelle du pilote industriel et participer au dimensionnement de centrales de types CLC. / This work deals with the development, validation and application of a model of Chemical Looping Combustion (CLC) in a circulating fluidized bed system. Chapter 1 is an introduction on Chemical Looping Combustion. It rst presents the most important utilizations of coal in the energy industry. Then, it shows that because of the CO2 capture policy, new technologies have been developed in the frame of post-combustion, pre-combustion and oxy-combustion. Then, the Chemical Looping Combustion technology is presented. It introduces multiple challenges: the choice of the Metal Oxide or the denition of the operating point for the fuel reactor. Finally, it shows that there are two specicities for CFD modeling: the influence of the collisions between particles of different species and the local production of gas in the reactor due to the gasication of coal particles. Chapter 2 outlines the CFD modeling approach: the Eulerian-Eulerian approach extended to flows involving different types of particles and coupled with the chemical reactions. Chapter 3 consists in the validation of the CFD model on mono-solid (monodisperse and poly-disperse) and poly-solid flows with the experimental results coming from an ALSTOM pilot plant based at the Universite Tchnologique de Compiegne (France). The relevance of modeling the polydispersity of a solid phase is shown and the influence of small particles in a CFB of large particles is characterized. This chapter shows that the pilot plant hydrodynamics can be predicted by an Eulerian-Eulerian approach. Chapter 4 consists in the validation of the CFD model on an extreme bi-solid CFB of particles of same density but whith a large particle diameter ratio. Moreover, the terminal settling velocity of the largest particles are twice bigger than the fluidization velocity: the hydrodynamics of the large particles are given by the hydrodynamics of the smallest. An experiment performed by Fabre (1995) showed that large particles can circulate through the bed in those operating conditions. Our simulations predicted a circulation of large particles, but underestimated it. It is shown that it can be due to mesh size eect. Finally, a simulation in a periodic box of this case was dened and allowed us to show the major influence of collisions between species. Chapter 5 presents the simulation of a hot reactive CLC pilot plant under construction in Darmstadt (Germany). The simulations account for the chemical reactions and describe its eect on the hydrodynamics. Different geometries and operating conditions are tested.
403

Développement d’un procédé de stockage d’énergie thermique haute température par voie thermochimique / Development of a high temperature thermochemical heat energy storage process

Pardo, Pierre 09 December 2013 (has links)
Les travaux présentés dans cette thèse concernent le développement d’un procédé de stockage d’énergie thermique haute température par voie thermochimique en vue d’une application dans une centrale solaire à concentration. Un état de l’art des technologies de stockage d’énergie thermique haute température par voie thermochimique a permis de définir le couple réactionnel et la technologie les mieux adaptés au procédé. Ainsi, la réaction réversible Ca(OH)2(s) = CaO(s) + H2O(g) est mise en oeuvre dans un réacteur à lit fluidisé. Une étude expérimentale a permis de démontrer la faisabilité du procédé en stockant et en déstockant l’énergie à une même température et en mettant en oeuvre 50 cycles de charge/décharge de l’énergie sans perte de réversibilité. L’utilisation d’un modèle monodimensionnel couplant les phénomènes chimiques, thermiques et hydrodynamiques à l’intérieur du réacteur a permis de mettre en évidence l’influence des conditions opératoires sur les performances du système. Les premiers pas vers une extrapolation industrielle font l’objet de la dernière partie de ces travaux, en présentant l’analyse énergétique d’une centrale solaire à concentration intégrant le procédé de stockage développé et en présentant une étude expérimentale mettant en oeuvre un solide de type industriel dans le réacteur. / This PhD thesis concerns the development of a high temperature thermochemical heat energy storage process for an application in concentrated solar power plants. A literature review allows the identification of both the best reaction couple and technology to operate the process. Thus, the Ca(OH)2(s) = CaO(s) + H2O(g) reversible reaction is carried out in a fluidized bed reactor. The experimental study demonstrated the process feasibility. Thermal energy has been charged and discharged at the same temperature and 50 cycles have been performed without any loss of reversibility. A 1D model coupling the chemical, thermal and hydrodynamic phenomena inside the reactor has been developed to study the operating parameter effects on the process performance. The last section of this work deals with the first steps towards an industrial scale-up. An energetic analysis of a concentrated solar power plant integrating the developed storage process is detailed as well as the reactions implementation with an industrial solid.
404

Approche multi-échelle pour les écoulements fluide-particules / Multiscale approach for particulate flows

Bernard, Manuel 06 November 2014 (has links)
Cette thèse porte sur l’étude numérique de la dynamique des écoulements fluide-particules au sein des lits fluidisés denses. Le but de ces travaux est d’améliorer la compréhension des phénomènes qui s’y déroulent afin d’optimiser les performances des procédés industriels confrontés à ces écoulements diphasiques. En effet, la diversité des échelles de longueur et les différents types d’interaction fluide-solide et solide-solide rencontrées dans ce type de configuration rendent cette catégorie d’écoulement particulièrement complexe et intéressante à étudier. Le modèle développé à cet effet permet de suivre individuellement la trajectoire des particules et de traiter les collisions avec leurs voisines tandis que la phase fluide est décrite de façon localement moyennée. Dans ce mémoire, nous présentons tout d’abord les origines physiques du phénomène de fluidisation d’une population de particules et les grandeurs physiques qui le caractérisent. Puis nous détaillons le modèle Euler-Lagrange implémenté et présentons une série de tests de validation basés sur des résultats théoriques et des comparaisons à des résultats expérimentaux. Cet outil numérique est ensuite employé pour simuler et étudier des lits fluidisés comportant jusqu’à plusieurs dizaines de millions de particules. Enfin, nous comparons des simulations réalisées conjointement à l’échelle micro et avec le modèle développé au cours de cette thèse à l’échelle méso. / This thesis deals with numerical analysis of particulate flows within dense fluidized beds. The aim of this work is to improve phenomena understanding in such flows in order to optimize engineering processes design. Wide variety of length scales and various fluid-solid and solid-solid interactions makes complex and challenging this type of flows study. The present developed model permits individual particle tracking and handle particles collisions whereas fluid flow is space averaged. In this manuscript, we first present origins of fluidization phenomenon and describe the macroscopic quantities which characterize it. Then we introduce the Euler-Lagrange model we developed and detail its numerical implementation. Moreover, we present a bench of validation tests based both on theoretical results and experimental data comparison. This numerical tool is then used to simulate and study fluidized beds containing up to several tenth of millions particles. Finally, we compare simulations performed both at micro and meso scales, i.e. with the model developed during this thesis.
405

Simulação numérica de escoamentos gás-sólido em leito fluidizado borbulhante utilizando a teoria cinética dos escoamentos granulares

Mineto, Andreza Tangerino [UNESP] 12 January 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:25:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-12Bitstream added on 2014-06-13T18:26:27Z : No. of bitstreams: 1 mineto_at_me_bauru.pdf: 1189778 bytes, checksum: 6d950fce04e9cbf0b24c319a7847ead4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No presente trabalho desenvolve-se um estudo de modelagem matemática e simulação numérica do escoamento gás-sólido em um leito fuidizado borbulhante. É apresentado o modelo hidrodinâmico, A, para escoamentos bifásicos gás-solido considerando a Teoria Cinética dos Escoamentos Granulares. É usado o modelo Euleriano de duas fases separadas considerando a modelagem do tensor das tensões da fase sólida através do atrito entre as partículas e da teoria cinética dos escoamentos granulares. O código fonte MFIX (Multiphase Flow with Interphase eXchanges) desenvolvido no NETL (National Energy Technology Laboratory) é utilizado para as simulações numéricas. Os resultados de simulação são obtidos resolvendo a temperatura granular algebricamente ou através de uma equação diferencial parcial. Obtêm-se resultados mais realísticos no uso da EDP com condição de contorno de deslizamento parcial na parede. Uma variação no diâmetro das partículas (partículas do grupo B e do grupo A/B) é investigada, concluindo-se que deve ser acrescentado ao código MFIX outros parâmetros físico para simulações com partículas do grupo A/B. / In the present work is described a mathematical model and numerical simulation of gas-solid flow in the bubbling fluidized bed. It is presented the hydrodynamic model, A, for gas-solid flow considering the Kinetic Theory of Granular Flows. It is used the two fluids Eulerian model where the solid phase stress tensor is modeled considering the friction between the particles and the kinetic theory of granular flows. The code MFIX (Multiphase Flow with Interphase eXchanges) developed in NETL (National Energy Tecnology Laboratory) is used for numerical simulations. The results are obtained with the compute of the granular temperature using a partial differential equation or an algebraic expression. It was obtained more realistic results when is used a PDE with boundary conditions of the partial slip. A variation in the diameter of the particles (particles in Group B and Group A/B) it is analyzed. It is also concluded that should be added to the code MFIX other physical parameters for simulations with particles of group A/B.
406

Produção microbiológica de ácido propiônico, 1,3-propanodiol e hidrogênio a partir de glicerol bruto em reator anaeróbio de leito fluidizado

Nazareth, Talita Corrêa 24 April 2015 (has links)
Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-30T18:55:37Z No. of bitstreams: 1 DissTCN.pdf: 1750863 bytes, checksum: 7f270955d14599a5df96c67c05642037 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-30T19:05:44Z (GMT) No. of bitstreams: 1 DissTCN.pdf: 1750863 bytes, checksum: 7f270955d14599a5df96c67c05642037 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-30T19:05:52Z (GMT) No. of bitstreams: 1 DissTCN.pdf: 1750863 bytes, checksum: 7f270955d14599a5df96c67c05642037 (MD5) / Made available in DSpace on 2016-09-30T19:11:43Z (GMT). No. of bitstreams: 1 DissTCN.pdf: 1750863 bytes, checksum: 7f270955d14599a5df96c67c05642037 (MD5) Previous issue date: 2015-04-24 / Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM) / This study aimed to produce propionic acid, 1,3-propanediol and hydrogen in anaerobic fluidized bed reactor with grounded tire as support material for immobilization of biomass. The experiment took place during 278 days in six distinct phases distributed according to the hydraulic retention time (HRT), which ranged between 8 and 0.5 h. The reactor was maintained at mesophilic conditions (30 ° C) with controlled pH between 4.5 and 5.5 and crude glycerol as carbon source at a concentration of 5 g L-1. The inoculum used in the experiment was derived from the processing of poultry slaughterhouse wastewater station. The results show that the consumption of substrate conversion reached the highest value (89.8 %) in HRT of 6 hours. The biogas produced was composed of H2 and CO2 and the greatest recorded content of H2 has been reached (81.2%) in HRT of 4 hours. The principal soluble metabolite produced were propionic acid and 1,3-propanediol, with maximum yields of 1,77 and 0,82 mol.molglicerol -1, respectively. Both maximum yields were achieved in HRT of 8 h. At all stages of this work occurred predominantly propionic acid, with maximum molar percentage (96,9 %) achieved in HRT of 0,5 h. The second predominant metabolite obtained was 1,3- propanediol, achieving greater molar percentage (29.4%) in HRT of 6 hours. / O presente trabalho teve por objetivo produzir ácido propiônico, 1,3-propanodiol e hidrogênio em reator anaeróbio de leito fluidizado com pneu triturado como material suporte para adesão da biomassa. O experimento ocorreu durante 278 dias, em seis fases distintas distribuídas em função do tempo de detenção hidráulica (TDH), que variou entre 8 e 0,5 h. O reator foi mantido em condições mesofílicas (30 °C), com pH controlado entre 4,5 e 5,5 e possuía glicerol bruto como fonte de carbono na concentração de 5 g L-1. O inóculo utilizado no experimento foi proveniente de estação de tratamento de efluente de abatedouro de aves. Os resultados obtidos mostram que o consumo de substrato atingiu o maior valor de conversão (89,8 %) no TDH de 6 h. O biogás produzido foi composto de H2 e CO2, tendo o maior conteúdo de H2 registado (81,2 %) no TDH de 4 h. Os principais metabólitos solúveis obtidos foram ácido propiônico e 1,3-propanodiol com rendimentos máximos de 1,77 e 0,82 mol.molglicerol -1, respectivamente. Ambos os rendimentos máximos foram atingidos no TDH de 8 h. Em todas as fases apresentadas, ocorreu a predominância de ácido propiônico, sendo a maior porcentagem molar (96,9 %) atingida no TDH de 0,5 h. O segundo metabólito mais produzido foi o 1,3-propanodiol, alcançando maior porcentagem molar (29,4 %) no TDH de 6 h.
407

Estudo da dinâmica do escoamento gás-sólido em resfriadores de catalisador de FCC usando fluidodinâmica computacional (CFD)

Lucar Monzón, Edgar Manuel 26 January 2017 (has links)
Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-06-05T18:05:00Z No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-05T18:19:12Z (GMT) No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-05T18:19:18Z (GMT) No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) / Made available in DSpace on 2017-06-05T18:24:29Z (GMT). No. of bitstreams: 1 DissEMLM.pdf: 4999609 bytes, checksum: 95744c602244ec5bde3892ae1ab471e5 (MD5) Previous issue date: 2017-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The fluid catalytic cracking (FCC) is an important process in oil industry, since it converts heavier fractions in lighter ones, which are more valuable. The catalyst particles (typically m) are deactivated during the reacting process and need to be regenerated before returning to the reactor. Temperature is a key factor that promotes coke formation and deactivation inside the reactor. As a consequence, it is necessary to cool down the solid catalyst particles before returning them to the reactor. The cooling system is usually outside the regenerator in a specific designed heat exchanger, that uses water as cold fluid. The catalyst cooler was not much studied before and many contributions can be made for improvements and intensification. The goal of this work was to contribute with this topic, using Computational Fluid Dynamics (CFD) to evaluate the gas-solid flow behavior in characteristic geometries of the catalyst cooler. Commercial package Fluent by ANSYS v14.5 was used during simulation and Eulerian model was applied for the solid phase. The volume fraction phase for the solid phase, solid and gas velocities were evaluated and described. The results were compared in terms of gas-solids flow in different geometries and showed a hydrodynamic explanation different from that currently used by the authors to justify the intensification of thermal exchange in this type of equipment. In short, longer solid-wall contact time will be primarily responsible for efficient heat transfer. / O craqueamento catalítico fluidizado é um processo amplamente utilizado no campo do refino de petróleo. Na unidade de craqueamento, frações pesadas são transformadas em outras mais leves e com maior valor de mercado (gasolina, diesel, naftas). Após o craqueamento, o catalisador é regenerado e retorna ao reator. A temperatura do catalisador é um parâmetro que possui forte influência sobre o processo. O resfriamento de catalisador é feito em unidades externas a fim de controlar a temperatura de entrada do catalisador no reator. O funcionamento deste sistema ainda foi pouco explorado e o objetivo deste trabalho foi o de simular o escoamento gás-sólido em geometrias características de colunas para resfriamento de catalisador com diferentes condições de operação, assim tentando contribuir com o conhecimento sobre este processo. Técnicas de Fluidodinâmica Computacional foram usadas para a simulação de diferentes geometrias com o programa comercial FLUENT do pacote ANSYS v14.5. As distribuições fração volumétrica dos sólidos e de velocidades do gás e fase particulada foram analisados como parâmetros de interesse hidrodinâmico. Os resultados foram comparados em termos de escoamento gás-sólido em diferentes geometrias e mostraram uma explicação hidrodinâmica diferente da atualmente utilizada pelos autores para justificar a intensificação de troca térmica em este tipo de equipamentos. Em suma, maior contato sólido-parede seria o principal responsável pela transferência eficiente de calor.
408

Construção e desenvolvimento de um secador de leito pulso-fluidizado para secagem de pastas e polpas

Martinelli, Leandro [UNESP] 08 July 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-08Bitstream added on 2014-06-13T19:11:27Z : No. of bitstreams: 1 martinelli_l_me_sjrp.pdf: 1675808 bytes, checksum: cfe68f960177993855a48c3037727299 (MD5) / 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)
409

Produção de hidrogênio e etanol através da fermentação acidogênica de águas residuárias agroindustriais em reator anaeróbio de leito fluidizado

Rosa, Paula Rúbia Ferreira 28 March 2014 (has links)
Made available in DSpace on 2016-06-02T19:55:39Z (GMT). No. of bitstreams: 1 5956.pdf: 2655473 bytes, checksum: dfaa0329652cfa24fb1dd3934c5b664b (MD5) Previous issue date: 2014-03-28 / Universidade Federal de Sao Carlos / The aim of this study was to evaluate the influence of hydraulic retention time (HRT), the origin of different inoculum (sludge from a UASB reactor for swine wastewater treatment and poultry slaughterhouse), and different carbon source (glucose, cassava processing wastewater and cheese whey) on the stability and efficiency of the anaerobic fluidized bed reactor (AFBR) for producing hydrogen. Twelve identical reactors were used, and in two reactors the mixture of glucose with cheese whey (R1S, R2S) was used as a substrate, six reactors were used with mix cassava processing wastewater and glucose (R1M, R2M, R3M and R4M). It was evaluated use of cheese whey (R3S, R4S, R5s and R6S) and cassava processing wastewater (R5M and R6M). The AFBRs were inoculated with sludge from a UASB reactor used in the treatment of swine wastewater (R1S, R3S, R1M, R3M, R5S, R6S, R5M and R6M) and sludge from a UASB reactor that treated poultry slaughterhouse wastewater (R2S, R4S, R2M, R4M), both heat treated. Variations of HRT (12-1 h) and substrate concentrations were performed (2-15 g .L -1), with temperature control at 30 ° C. The reactors that used cheese whey as substrate showed a greatest potential for hydrogen production, with yields (HY) of 3.2 mmolH2.g-1COD (R6S) and 2.6 mmolH2.g-1COD (R5S) were obtained by applying a HRT of 6 and 14 hours, with a concentration of 3 and 5 g.L-1, respectively. Both substrates showed potential for the production of ethanol with yields (EtOHY) of 4.2 mmolEtOH.g-1COD (R6M) and 3.5 mmolEtOH.g-1COD (R2S). In the comparison between the two inocula used, both showed a balance in terms of hydrogen production, but in terms of ethanol production, the sludge from poultry slaughterhouse showed highest potential. By cloning and sequencing of the 16S rRNA gene for bacteria domain reactor R4S (whey), there was a predominance of the genus Selenomonas (69 % of the sequences) and Clostridium (8 % of the sequences). For the reactor R3M (glucose and cassava) analyzes cloning and sequencing of bacterial consortium revealed similarities with Lactobaccilus. As for the archaeal domain, the sequencing of the 16S rRNA gene had highly similar to the genus Methanobacterium (98.5 % and 95 % of the sequences), for R4S and R3M, respectively reactors. / O objetivo deste estudo foi avaliar a influência do tempo de detenção hidráulica (TDH), da origem de diferentes inóculos (lodo de suínos e lodo de aves), e da fonte de carbono (glicose, manipueira e soro de queijo) sobre a estabilidade e eficiência do reator anaeróbio de leito fluidizado (RALF) na produção de hidrogênio e etanol. Foram utilizados doze reatores idênticos, sendo que em dois reatores foram utilizados mistura de glicose com soro de queijo (R1S, R2S), seis reatores foram utilizados a mistura de água do processamento da mandioca (manipueira) e glicose (R1M, R2M, R3M e R4M). Também foi avaliado o uso individual do soro de queijo (R3S, R4S, R5S e R6S) e da manipueira (R5M e R6M). Os RALFs foram inoculados com lodo proveniente do tratamento de águas residuárias de suinocultura (R1S, R3S, R1M, R3M, R5S, R6S, R5M e R6M) e de águas residuárias do abatedouro de aves (R2S, R4S, R2M, R4M), ambos tratados termicamente. Foram realizadas variações de TDH (14-1 h) e concentrações de substrato (2- 15 g. L-1), com controle de temperatura a 30°C. Os reatores que utilizaram soro de queijo como substrato apresentaram um maior potencial para a produção de hidrogênio, com rendimentos (HY) de 3,2 mmolH2.g-1DQO (R6S) e 2,6 mmolH2.g-1DQO (R5S), por meio da aplicação de um TDH de 6 e 14 horas, com uma concentração de 3 e 5 g.L-1, respectivamente. Ambos os substratos apresentaram potencial para a produção de etanol, com rendimentos (EtOHY) de 4,2 mmolEtOH.g-1DQO (R6M) e 3,5 mmolEtOH.g-1DQO (R2S). Na comparação entre os dois inóculos utilizados, ambos apresentaram um equilíbrio em termos de produção de hidrogênio, porém em termos de produção de etanol, o lodo proveniente do abatedouro de aves apresentou um maior potencial. Por meio da clonagem e sequenciamento do gene RNAr 16S para o domínio bactéria do reator R4S (soro de queijo), houve a predominância do gênero Selenomonas (69% das sequências) e do gênero Clostridium (8% das sequências). Para o reator R3M (glicose e manipueira) as análises de clonagem e sequenciamento do consórcio bacteriano revelaram semelhanças com Lactobaccilus. Já para o domínio archaea, o sequenciamento do gene RNAr 16S, teve altas similaridades com gênero Methanobacterium (98,5% e 95% das sequências), para os reatores R4S e R3M, respectivamente.
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Efeito da velocidade ascensional na produção de hidrogênio em reator anaeróbio de leito fluidizado

Reis, Cristiane Marques dos 30 August 2010 (has links)
Made available in DSpace on 2016-06-02T19:56:41Z (GMT). No. of bitstreams: 1 3335.pdf: 2600508 bytes, checksum: 7bd7dedf1baa69c50930a1552ca3cb12 (MD5) Previous issue date: 2010-08-30 / Financiadora de Estudos e Projetos / This study evaluated the influence of the upflow velocity in anaerobic fluidized bed reactor to produce hydrogen. In order to compare that effect, four reactors were used under different upflow velocities each: 0.30; 0.60; 1.24 and 1.88 cm.s-1. Expanded clay was used as support material for immobilization. A synthetic wastewater containing glucose (5000 mg.L-1) was used as substrate. Reactor R124 that was operated under minimum fluidization velocity (1.24 cm.s-1) showed the best values for hydrogen production. The maximum hydrogen production rate was found to be 1.22 L.h-1.L-1. The maximum hydrogen yield was 2.55 mol H2 mol-1 glucose and the biogas content ranged between 30,5 and 61,8 %. No methane was generated. The optimum TDH for expanded bed reactors was 1h while in fluidized bed reactors were 2h. Ethanol was the main metabolite produced, suggesting an ethanol-type fermentation. No trends were shown regardless of the upflow velocity imposed to the system. However, the higher the velocity applied, the higher the hydrogen production rate. / Neste trabalho foi analisada a influência da velocidade ascensional em reator anaeróbio de leito fluidizado para a produção de hidrogênio. A fim de comparação foram empregados quatro reatores apresentando diferentes valores de velocidade de ascensão do fluido, a saber: 0,30 (R030); 0,60 (R060); 1,24 (R124) e 1,88 cm.s-1 (R188). Como material suporte de imobilização foi utilizada a argila expandida. Uma água residuária sintética contendo glicose (5000 mg.L-1) foi utilizada como substrato. O reator R124 trabalhando na velocidade de mínima fluidização foi o reator que apresentou as melhores condições para a produção de hidrogênio. O valor máximo de produção volumétrica de hidrogênio foi de 1,22 L.h-1.L-1. O rendimento foi de 2,55 mol H2 .mol-1 glicose e o conteúdo no biogás entre 30,5 e 61,8 %. Não houve produção de metano em nenhum dos reatores empregados. O TDH ótimo observado para os reatores expandidos foi em 1h enquanto que nos reatores fluidizados o TDH ótimo foi de 2h. Etanol foi o principal metabólito produzido, sugerindo que a rota etanólica de produção foi predominante. Em relação à velocidade ascensional aplicada não foi observada relação com o rendimento nem com o conteúdo do biogás. Porém, quanto maior a velocidade ascensional aplicada, maior a produção volumétrica de H2.

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