Les dysfonctionnements observés dans les enceintes de conversion thermochimique tels que les zones mortes et les courts-Circuits conduisent en général à une mauvaise valorisation de la ressource énergétique et à une pollution atmosphérique. Ils trouvent leur origine dans les conditions aérauliques au sein de ces enceintes. Ils pourront alors être évités par une meilleure maîtrise de ces écoulements. Nous proposons dans ce travail d’une part, le développement d’un nouvel outil pour la détermination de la distribution des temps de séjour de la phase solide, basé sur la luminescence de particules préalablement enrobées de pigments phosphorescents. Cette méthode systémique, optique, non intrusive et souple d’emploi a été mise en place à l’échelle laboratoire sur un banc d’essais aéraulique. D’autre part, nous avons développé un modèle numérique permettant de déterminer la distribution des temps de séjour afin de maîtriser les écoulements à la sortie des enceintes en vue de les optimiser et les extrapoler à l’échelle industrielle. Cette approche analytique est basée sur une modélisation par couplage MFN de type volumes finis du comportement d’un fluide à l’aide du Code Saturne et DEM de type éléments discrets du comportement du solide à l’aide du code SIGRAME. Enfin une confrontation de la DTS du modèle numérique avec laDTS expérimentale a été réalisée. / Dysfunctions observed in thermochemical conversion reactors like dead zones and short circuits generally lead to inaccurate pricing of energy resources and air pollution. They originate in the air flow conditions in these aeraulic reactor. They can then be avoided by a better control of these flows. We propose in this work to develop a new tool for determining the distribution of residence time of the solid phase, based on the luminescence of particles previously coated with phosphorescent pigments. This optical method, non-Intrusive and flexible, has been implemented at a laboratory scale, on an aeraulic test bench.On the other hand, we have developed a numerical model allowing to determine the distribution of the residence time to master the flows at the exit of surrounding walls to optimize them and extrapolate them at the industrial scale. This analytical approach is based on a modelling by coupling MFN by finite volume types via the Code Saturn and DEM by discrete elements of the solid behavior by means of the code SIGRAME. Finally a confrontation of the DTS of the digital model with the experimental DTS has been done.

Orientador: Maria Regina Wolf Maciel / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-27T09:30:10Z (GMT). No. of bitstreams: 1 JaimesFigueroa_JaiverEfren_D.pdf: 4291833 bytes, checksum: dc5592f8288a01f2f792aac9bf02f01b (MD5) Previous issue date: 2015 / Resumo: Os processos termoquímicos permitem a conversão da biomassa em outros produtos de maior interesse e valor agregado. Dentre os processos termoquímicos destacam-se a pirólise e a gaseificação, sendo o alcatrão e gases, os principais produtos resultantes. Estes produtos possuem um grande potencial como intermediários químicos, combustíveis, lubrificantes e energia, tornando os processos termoquímicos muito atrativos. Este trabalho teve como objetivo avaliar experimentalmente dois processos termoquímicos: pirólise e gaseificação, usando bagaço de cana-de-açúcar como matéria-prima. Foram avaliados dois tipos de reatores: leito fixo e leito fluidizado. Inicialmente, foi realizada uma revisão bibliográfica para a obtenção das propriedades físico-químicas da matéria-prima, valores típicos sobre dimensionamento de reatores, cinéticas de reação e características dos produtos obtidos pela via termoquímica, com a finalidade de estudar o comportamento fluidodinâmico do sistema. Posteriormente, foi realizada uma simulação no software comercial ANSYS-FLUENT V12TM, obtendo-se pequenos desvios entre os valores preditos e os encontrados na literatura, o que gerou uma ferramenta computacional com potencial para avaliação dos processos termoquímicos utilizando material lignocelulósico. Após o estudo computacional, foram realizados dois estudos experimentais: um do processo de pirólise e outro de gaseificação. Os estudos experimentais foram realizados usando dois tipos de reatores com características diferentes, quando comparados aos reatores encontrados na literatura. A pirólise lenta a altas temperaturas do bagaço foi desenvolvida em reator de leito fixo em batelada, contendo uma mistura de bagaço e alumina/sílica (carga máxima de bagaço 4 g). Foram testadas várias temperaturas, superiores a 500 °C, e encontrado que um aumento nesta variável significou em um aumento da quantidade de gases e diminuição de carvão produzido. O alcatrão obtido foi independente da temperatura (20 % mássico). Utilizando o mesmo reator, foi realizada uma reação de gaseificação de bagaço de cana-de-açúcar a 900 °C e relação mássica vapor/bagaço igual a 2,0, obtendo-se maior rendimento de gases e menor de carvão. Além disso, o gás produzido continha porcentagem maior de hidrogênio quando comparado ao gás obtido por pirólise empregando a mesma temperatura. A gaseificação do bagaço foi realizada em um reator de leito fluidizado (elaborado e desenvolvido pelo grupo de pesquisa LOPCA/BIOEN/FEQ/UNICAMP para esta tese). Este reator foi instalado, testado e colocado em funcionamento com uma vazão de bagaço de até 3 kg/h. As reações foram feitas usando diferentes relações ER (razão mássica entre as relações (ar/bagaço) e (ar necessário para combustão completa/bagaço). Cada relação ER testada proporcionava uma temperatura de reação diferente, obtendo-se uma distribuição de produtos com características diferentes entre si. Os produtos da gaseificação foram caracterizados. Valores de ER mais elevados ofereceram maiores temperaturas de reação e, consequentemente, maiores rendimentos de gases e porcentagens de H2 e CO / Abstract: The thermochemical processes allow the biomass conversion in others products, producing simpler structures, which are more interesting. Two main thermochemical processes are the pyrolysis and gasification, which produce tar and gases. These products have an enormous potential as intermediate chemical compounds, fuels, lubricants and energy, making the thermochemical processes very relevant. In this work, both processes aforementioned were object of experimental study, using sugarcane bagasse as raw material. Two different reactors were analyzed: fixed bed and fluidized bed. A bibliographic research was made as a starting point, collecting enough information about the properties of the raw material, typical dimensions of the reactors, reaction kinetics and characteristics of the products. In order to study the fluid-dynamic behavior of the system some simulations were performed, using the ANSYS-FLUENT V12TM software. The simulation results presented small deviation compared to the experimental results reported on the literature, which indicates that the simulated system is a powerful tool to validate thermochemical processes that involve lignocellulosic materials. Subsequently, two experimental studies were developed: one for pyrolysis and other for gasification. For each process mentioned before, we used two types of reactors that differ from the reactors found on the literature. Bagasse pyrolysis was made on a fixed bed batch reactor, using a mixture of bagasse and alumina-silica (the bagasse does not exceed 4 grams). Different temperatures above 500 ºC were used, showing that the quantity of obtained gases were proportional to the temperature, while the quantity of carbon was inversely proportional. On the other hand, the tar produced in the reaction does not depend on the temperature (20 % mass). The same reactor was used to do the gasification of sugarcane bagasse at 900 ºC and a steam/bagasse mass ratio of 2.0, obtaining a bigger production of gas and smaller production of carbon. Additionally, the obtained gas contains a bigger proportion of hydrogen than the gas produced with pyrolysis, using the same temperature. Finally, other gasification were performed, using a fluidized bed reactor acquired by the LOPCA/BIOEN/FEQ/UNICAMP research group, which produces a bagasse output up to 3 kg/h. All reactions were made using different ER relations (air/bagasse mass ratio). Each ER relation produced a different reaction temperature, obtaining a product distribution with different characteristics between them. The products obtained were characterized. The higher ER values offered bigger temperatures of reaction and consequently, higher yield of gas and percentages of H2 and CO proportions / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientadores: Maria Regina Wolf Maciel, Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-28T02:11:55Z (GMT). No. of bitstreams: 1 Miranda_JulioCesardeCarvalho_D.pdf: 11420052 bytes, checksum: 1d66d50744b41020ecf572a3b96b2561 (MD5) Previous issue date: 2015 / Resumo: O gás de síntese (syngas) é conhecido principalmente pelo seu uso na produção de amônia (Processo Harber-Bosch) e hidrocarbonetos (Processo Fischer-Tropsch). No entano, uma rota menos explorada para a produção de produtos químicos, entre eles alcoóis e outros oxigenados, a partir do gás de síntese, vem ganhando atenção nos últimos anos. Nessa rota, a matéria-prima inicial, como a biomassa é inicialmente gaseificada ao syngas, o qual é reformado, limpo, comprimido e finalmente convertido cataliticamente em uma mistura de alcoóis e produtos oxigenados que, após os passos de separação, atingem a pureza necessária para sua comercialização. Nesse trabalho, a rota termoquímica, como é conhecida, é utilizada com o objetivo de se produzir etanol a partir do syngas. Utilizando o simulador comercial ASPEN Plus v7.3, foram propostos 9 casos de estudo utilizando 3 categorias diferentes de catalisador em 4 diferentes layouts de processo. Todos os casos de estudo foram avaliados quanto à sua produtividade, ao seu consumo de energia e aspectos de importância econômica. Foi possível concluir a partir das análises feitas que cada uma das categorias de catalisador possui vantagens e desvantagens dependendo do contexto econômico, podendo-se citar a diferenciada produção de hidrocarbonetos e outros oxigenados além do etanol, a geração de água, o número de unidades de separação e o consumo de energia / Abstract: Synthesis gas (syngas) is mostly known by its use on ammonia (Harber-Bosch process) and hydrocarbons (Fischer-Tropsch process) production processes. However, a less explored route to produce chemical products, among them alcohols and other oxygenates, from syngas is gaining attention over the last few years. In this route, an initial feedstock as biomass is firstly gasified to synthesis gas, which is reformed, cleaned, compressed and finally catalytically converted in a mixture of alcohols and oxygenated products that after separation steps attain sufficient purity to be sold. In this work, the thermochemical route, as it is known, is used aiming ethanol production from syngas. Using the commercial simulator ASPEN Plus v7.3, 9 case studies were proposed using 3 different categories of catalysts in 4 different process layouts. All the cases were evaluated regarding their productivity, their energy consumption, and aspects of economic importance. It was possible to conclude from the analysis that each of the catalyst categories has advantages and disadvantages depending on the economic context, among them the different proportion of hydrocarbons and other oxygenated products besides ethanol, water generation, number of separation unities and energy consumption / Doutorado / Engenharia Química / Doutor em Engenharia Química

This thesis comprises an assessment of a novel concept to produce high purity hydrogen using mixed oxide ion/electronic conductor (MIEC) membranes and energy provided by solar concentrators (i.e. parabolic troughs or parabolic dishes). The vision of this concept is that it will be used to produce tons of high purity hydrogen for fuel cells, which is a scarce commodity with an increasing demand from residential and transportation power generation applications. The MIEC membrane activates a steam reforming reaction between water and methane to produce hydrogen of high purity on the water side and syngas on the fuel side. Expectations are that this concept has cost advantages over other thermo-chemical water-dissociation methods, using a lower temperature and no electricity for the reaction process. The thesis’ focus is on techno-economic aspects of the concept, as part of an application process for project financing by the European Commission of Research and Innovation. The assessment in the thesis shows that the overall efficiency of the concept is expected to be very low. It also identifies the difficulties of providing stable working conditions for the concept. Suggestions to improve the concept are proposed to address the most urgent problems of the concept. These suggestions illuminate the opportunities that actually do exist to combine MIEC membranes, solar energy and thermo-chemical water splitting into a working concept. These improvements include using parabolic dishes instead of parabolic troughs, using furnaces with control systems and using a viable flow rate. The production capacity of high purity hydrogen is expected to be approximately 89 mg per minute in a membrane bundle (i.e. 150 thin membrane fibers with an oxygen permeation flux of 1 ml cm-2 min-1) if these improvements were implemented. This would imply that the studied concept needs further development to produce high purity hydrogen in quantities that could meet the shortage on the commercial fuel cell markets.

Thermochemical technologies have been proven effective in treating municipal solid waste (MSW) for many years. China, with a rapid increase of MSW, plans to implement more environmental friendly ways to treat MSW than landfill, which treats about 79 % of total MSW currently. The aim of this master thesis was to find out a suitable thermochemical technology to treat MSW in Shanghai, China. Several different thermochemical technologies are compared in this thesis and plasma gasification was selected for a case study in Shanghai. A model of the plasma gasification plant was created and analysed. Other processes in the plant including MSW pre-treating and gas cleaning are also proposed. By calculating the energy balance, it is demonstrated that plasma treatment of 1000 ton/day MSW with 70 % moisture reaches an efficiency of 33.5 % when producing electricity, which is higher than an incineration WtE plant (27 % maximum) and a gasification WtE plant (30 % maximum). Besides of the efficiency comparison, costs and environmental impacts of different technologies are also compared in this paper. The result indicated that given the characteristics and management situation of MSW in Shanghai, plasma gasification is a better choice to treat MSW in Shanghai.

No description available.

With the global deployment of renewable energy generation at record rates, clean energy is steadily becoming competitive with its fossil-fuel counterparts. However, further expansion is limited by the inherent intermittency of renewable energy sources (solar, wind, wave, etc.), which typically do not match with daily and seasonal variations of global (and local) energy demand. Thermochemical energy storage (TCES) has demonstrated strong potential in being a technological pathway to provide on-demand process heat and handle the intrinsic variations in renewable energy generation and energy demand. TCES works on the premise of excess renewable heat driving an endothermic reduction reaction, in which thermal energy is converted to chemical potential energy. The reversed exothermic oxidation reaction is subsequently triggered (on-demand) to recover thermal energy which can be used as process heat. While the benefits of TCES have been demonstrated experimentally at the lab-scale, accurate numerical modeling of TCES reactors is key for future development, optimization, and implementation of large industrial-scale energy storage systems. This dissertation focuses on the development of continuum-scale models to accurately simulate and predict performance of high temperature (up to 1500 °C) moving-bed reactors for TCES. The efficacy of present volume- averaging approaches is briefly reviewed, with the major focus of the work on the development of multi-dimensional multi-physics models of increasing complexity for moving-bed TCES reduction and oxidation reactors.

[pt] O presente trabalho consiste de um modelo matemático termoquímico de simulação do processo Tecnored de produção de ferro primário, construído através do estudo e equacionamento da fenomenologia do processo, levando em consideração os aspectos termodinâmicos e operacionais, bem como a geometria do reator. Apesar de ser um modelo estático, considerações cinéticas de laboratório e de planta piloto foram usadas para estimar a extensão das principais reações químicas nas diferentes regiões do forno. Para construção do modelo o reator foi dividido em três zonas, a saber: cuba superior, zona de amolecimento e fusão, e cuba inferior. Para cada uma das zonas foram descritas as fenomenologias e reações químicas envolvidas, condicionadas ao balanço global das espécies químicas presentes no processo. As saídas do programa permitiram uma análise da engenharia de processo global e estagiada. Através do modelo construído é possível prever o comportamento do processo com diferentes tipos de matériasprimas e em diferentes condições operacionais. Adicionalmente, o modelo servirá para a checagem da operação do primeiro forno industrial desta tecnologia, atualmente em construção, comparando com os dados obtidos através da operação da planta piloto. Os resultados obtidos mostraram que a técnica de modelagem utilizada constitui-se em uma poderosa ferramenta de análise global e estagiada, confirmando as vantagens de consumo de combustível, eficiência energética e de geração de gases do processo Tecnored em relação à tecnologia tradicional do alto-forno. / [en] The present work consists of a Tecnored ironmaking process oriented thermo-chemical modeling, built after a thorough assessment of the process phenomena and considering besides the peculiarities of the reactor, a number of applicable thermodynamic and operational aspects. In spite of being a thermochemical model, bench scale and pilot plant based kinetics considerations have been taken in account in order to estimate the extension of the main reactions in different parts of the furnace. The framework involved the division of the furnace in three main zones, namely Solid-state Reduction Zone (SRZ), Softening and Melting Zone (SMZ) and Dripping and Hearth Zone (DHZ). In each of the zones the existing chemical processes and overall process phenomena have been evaluated conditional to the global mass balance ruling the process. The model developed shall be used onwards to predict the behavior of the process under different conditions of raw material usage and operational modes. Moreover, the model shall be applied to compare the results of the industrial plant (under construction) with the available bench and pilot plant data, with the intention of gathering information to be used in the optimization of the model and subsequently the process. The results obtained thus far show that the applied modeling technique is a powerful tool for the global and stage-wise analysis of the process, confirming the advantageous performance of the technology as far as fuel-rate, thermal efficiency and environmental soundness are concerned.

The air intake manifold is an integral part of modern internal combustion engines. Currently manufactured in glass fibre reinforced PA66, inquiries have been raised regarding a change of material to glass fibre reinforced PP. A new engine project is the purpose for which this proposed material is evaluated. The thermochemical environment in the air intake system puts high demands on the material. Ageing treatments and tensile testing was conducted on samples of the new material, as well as on the currently used PA66 to evaluate mechanical response of each material to treatments made to simulate the air intake environment. Furthermore, understanding of the chemical setup is lacking and needs to be studied. Experiments was performed to study the chemistry of the intake environment. Results indicated that PP can retain sufficient mechanical rigidity and strength when subjected to parameters made to simulate the air intake. Moreover, results regarding the chemical environment in the air intake system provided limited information.

This dissertation as a whole aims to provide the means to better understand hot-Jupiter planets through observing, performing thermochemical calculations, and modeling their atmospheres. We used Spitzer multi-wavelength secondary-eclipse observations to characterize planetary atmospheres. We chose targets with high signal-to-noise ratios, as their deep eclipses allow us to detect signatures of spectral features and assess planetary atmospheric structure and composition with greater certainty. Chapter 1 gives a short introduction. Chapter 2 presents the Spitzer secondary-eclipse analysis and atmospheric characterization of WASP-14b. The decrease in flux when a planet passes behind its host star reveals the planet dayside thermal emission, which, in turn, tells us about the atmospheric temperature and pressure profiles and molecular abundances. WASP-14b is a highly irradiated, transiting hot Jupiter. By applying a Bayesian approach in the atmospheric analysis, we found an absence of thermal inversion contrary to theoretical predictions. Chapter 3 describes the infrared observations of WASP-43b's Spitzer secondary eclipses, data analysis, and atmospheric characterization. WASP-43b is one of the closest-orbiting hot Jupiters, orbiting one of the coolest stars with a hot Jupiter. This configuration provided one of the strongest signal-to-noise ratios. The atmospheric analysis ruled out a strong thermal inversion in the dayside atmosphere of WASP-43b and put a nominal upper limit on the day-night energy redistribution. Chapter 4 presents an open-source Thermochemical Equilibrium Abundances (TEA) code and its application to several hot-Jupiter temperature and pressure models. TEA calculates the abundances of gaseous molecular species using the Gibbs free-energy minimization method within an iterative Lagrangian optimization scheme. The thermochemical equilibrium abundances obtained with TEA can be used to initialize atmospheric models of any planetary atmosphere. The code is written in Python, in a modular fashion, and it is available to the community via http://github.com/dzesmin/TEA. Chapter 5 presents my contributions to an open-source Bayesian Atmospheric Radiative Transfer (BART) code, and its application to WASP-43b. BART characterizes planetary atmospheres based on the observed spectroscopic information. It initializes a planetary atmospheric model, performs radiative-transfer calculations to produce models of planetary spectra, and using a statistical module compares models with observations. We describe the implementation of the initialization routines, the atmospheric profile generator, the eclipse module, the best-fit routines, and the contribution function module. We also present a comprehensive atmospheric analysis of all WASP-43b secondary-eclipse data obtained from the space- and ground-based observations using BART.