The United States holds the world's largest estimated reserves of coal and is also a net exporter of it. Coal gasification provides a cleaner way to utilize coal than directly burning it. Gasification is an incomplete oxidation process that converts various carbon-based feedstocks into clean synthetic gas (syngas), which can be used to produce electricity and mechanical power with significantly reduced emissions. Syngas can also be used as feedstock for making chemicals and various materials. A Computational Fluid Dynamics (CFD) scheme has been used to simulate the gasification process for many years. However, many sub-models still need to be developed and improved. The objective of this study is to use the improved CFD modeling to understand the thermal-flow behavior and the gasification process and to provide guidance in the design of more efficient and cheaper gasifiers. Fundamental research has been conducted to improve the gasification sub-models associated with the volatile thermal cracking, water-gas-shift (WGS) reaction, radiation effect, low-rank-coal gasification, coal to synthetic-natural-gas (SNG), and ash deposition mechanisms. The improved volatile thermal cracking model includes H2S and COS contents. A new empirical WGS reaction model is developed by matching the result with experimental data. A new coal demoisturization model is developed for evaporating the inherent moisture inside the coal particles during low-rank-coal gasification. An ash deposition model has also been developed. Moreover, the effect of different radiation models on the simulated result has been investigated, and the appropriate models are recommended. Some improved model tests are performed to help modify an industrial entrained-flow gasifier. A two-stage oxygen feeding scheme and a unique water quench design are investigated. For the two-stage oxygen feeding design, both experimental data and CFD predictions verify that it is feasible to reduce the peak temperature and achieve a more uniform temperature distribution in the gasifier by controlling the injection scheme without changing the composition and production rate of the syngas. Furthermore, the CFD simulation can acceptably approximate the thermal-flow and reaction behaviors in the coal gasification process, which can then be used as a preliminary screening tool for improving existing gasifiers’ performance and designing new gasifiers.

Anlagen zur Herstellung von Synthesegas (CO·H2) aus kohlenstoffhaltigen Rohstoffen werden durch hohe Temperaturen bis zu 1600 °C und Drücken bis zu 50 bar beansprucht und benötigen daher Schutz durch eine feuerfeste Ausmauerung. Zur Steigerung der Effizienz und Lebensdauer solcher Vergasungsanlagen ist die Entwicklung neuer keramischer Hochtemperaturwerkstoffe erforderlich. Solch ein Material stellt eine Al2O3-reiche Gießmasse dar, welche durch den gezielten Einsatz verschiedener ZrO2- und TiO2-Gehalte optimiert wurde. Es hat sich gezeigt, dass bereits durch die Zugabe geringer Mengen an ZrO2 bzw. TiO2 sowohl die Temperaturwechselbeständigkeit als auch die Korrosionsbeständigkeit von Al2O3 gegenüber Kohleschlacken erheblich verbessert werden kann, was auf die Ausbildung einer Spinell-Schutzschicht während des Korrosionsvorgangs zurückzuführen ist.

A utilização de briquetes de misturas de carvão fóssil e biomassa em substituição ao coque como agente redutor pode contribuir para a diminuição das emissões de CO2 à atmosfera no processo de redução de minério de ferro. O fenômeno do amolecimento e fluidificação do carvão fóssil durante o aquecimento permite que o mesmo absorva certa quantidade de materiais inertes à coqueificação durante o tratamento térmico. O objetivo deste trabalho é correlacionar o efeito das principais variáveis de processo de fabricação (temperatura e tempo de tratamento térmico, tamanho de partícula dos componentes, porosidade e proporção de carvão vegetal e carvão fóssil) sobre as propriedades obtidas (resistência mecânica e reatividade ao CO2) de briquetes compostos de misturas de carvão fóssil e carvão vegetal, para uso na indústria siderúrgica. Briquetes de dois formatos diferentes foram preparados em matriz cilíndrica e em maquina briquetadeira e tratados termicamente em forno vertical aquecido com resistência elétrica sob atmosfera de nitrogênio. A resistência à compressão dos briquetes foi analisada em função das seguintes variáveis: proporção de carvão fóssil e carvão vegetal, taxa de aquecimento do tratamento térmico e tamanho de partícula dos carvões. A reatividade ao CO2 dos briquetes tratados termicamente foi analisada em função das seguintes variáveis: temperatura de ensaio e vazão de CO2. Foram comparados os resultados obtidos de ambos os formatos de briquetes. Com o aumento da proporção de carvão vegetal nos briquetes cilíndricos de biocoque, a densidade aparente e a resistência à compressão após tratamento térmico aumentaram para as misturas contendo 5, 10 e 15% de carvão vegetal. A partir dessa composição (15% de carvão vegetal) tanto a densidade final quanto a resistência à compressão apresentaram diminuição. Encontrou-se que tanto os briquetes cilíndricos a verde quanto os briquetes tratados termicamente apresentam perda de resistência mecânica com o aumento do tamanho de partícula do carvão fóssil. Os melhores valores de resistência à compressão foram obtidos em briquetes feitos com carvão fóssil em mistura de 15% em peso de carvão vegetal, tamanho de partícula abaixo de 0,044 mm, tratados termicamente a 1100°C durante 8 horas. Com o aumento na adição de carvão vegetal nos briquetes compostos de carvão fóssil e carvão vegetal, observou-se um aumento da reatividade do biocoque ao CO2. As micrografias dos briquetes tratados termicamente mostraram que a textura dos briquetes tende a ser mais homogênea com aumento de carvão vegetal de madeira na mistura. Os briquetes de biocoque fabricados em briquetadeira permitiram a ampliação do processo de fabricação de briquetes a uma escala laboratorial maior e mostraram a viabilidade industrial na fabricação do biocoque. Encontrou-se que a adição de carvão vegetal de madeira na mistura influencia diretamente na resistência a compressão e a reatividade ao CO2, devido a diferentes fatores como a composição das cinzas da madeira, a diminuição da fluidez devido à ação do inerte na mistura a carbonizar, a formação de uma estrutura porosa dentro da matriz carbonosa. Não encontrou-se correlação entre o índice de alcalinidade dos briquetes e sua reatividade ao CO2. / The substitution of metallurgical coke by briquetted mixtures of coal and biomass as a reducing agent can lower the emissions of greenhouse gases (CO2) in the iron and steelmaking industry. The thermal plasticity of the coking coal can be used to absorb an amount of inert materials during heat treatment. The objective of this study is to correlate the effect of the main processes variables (heat treatment temperature and duration, particle size of the materials, porosity and coal and charcoal ratio) on the properties (compressive strength and CO2 reactivity) of briquetted mixtures of coal and charcoal. Two types of briquettes were produced, one in a cylindrical die and another in a laboratory briquetting machine. The briquettes were heat treated in a vertical electrical furnace under nitrogen atmosphere. The compressive strength of the briquettes was analyzed as a function of the following variables: coal and charcoal ratio, heating rate and particle size. The CO2 reactivity of the heat treated briquettes was analyzed as a function of the following variables: temperature and CO2 flow. For the cylindrical briquettes, the increase of charcoal (5, 10, 15 wt%) in the coal-charcoal mixtures caused an increase on the bulk density and on the compressive strength of the heat treated briquettes. Above 15 wt% of charcoal in the mixtures, the bulk density and the compressive strength decreased. It was found out that both green and heat treated briquettes had a decrease in compressive strength with the increase of the coal particle size. Optimum results of compressive strength were obtained in the briquettes with 15 wt% of charcoal, particle size <0.044 mm, heat treatment temperature of 1100°C for 8 hours. The increase in charcoal proportion caused an increase in the CO2 reactivity of the briquettes. The SEM micrographs of the heat treated briquettes showed that the texture of the briquettes tend to be more homogeneous with the increase of charcoal in the mixture. The properties of the briquettes produced in the laboratorial briquetting machine showed that a large scale production could be viable. Also, it was found out that the addition of wood charcoal in the mixture directly affects the compressive strength and the CO2 reactivity of the briquettes due to factors such as: the ashes composition, the decrease in fluidity because of the inert material in the mixture, the formation of a porous structure inside the carbon matrix. It was not found a relation between the alkalinity index and the CO2 reactivity in the briquettes.

Este trabalho tem como objetivo a identificação da melhor rota para a produção de combustíveis e derivados sintéticos através do desenvolvimento e aplicação de uma ferramenta metodológica desenvolvida tendo como base ferramentas da qualidade: diagrama de afinidade, diagrama de relações e matriz causa-efeito. Estes diagramas foram adaptados para a análise e discussão dos fatores positivos e negativos de cada item da tríade considerada: insumo-processo-produto. A partir desta análise foram criadas as matrizes de causa-efeito, também separadas em fatores positivos e negativos para os insumos: gás natural (GN), biomassa e carvão mineral; para os processos: produção de gás de síntese (syngas) a partir do GN, gaseificação do carvão e a gaseificação da biomassa; e para os produtos: óleo lubrificante, óleo diesel, nafta, metanol e amônia. A análise destas matrizes causa-efeito gerou a matriz final, denominada matriz saldo, que permitiu a seleção da rota mais adequada para a produção de combustíveis e derivados sintéticos. Dentre os insumos estudados, o gás natural apresentou evidentes vantagens e, consequentemente, o processo a ser utilizado deve ser a produção do syngas a partir do GN, e dentre os produtos o metanol apresentou maiores benefícios para ser produzido. / This paper aims to present to identify of the best route for the production of fuels and synthetic derivatives through the development and application of a methodological tool based on quality tools: affinity diagram, relations diagram and matrices cause-effect. The diagrams have been adapted for the analysis and discussion of positive and negative factors of each item of the triad considered: feedstock-process-product. From the analysis, matrices of cause and effect were created and also, separated into positive and negative factors for the inputs: natural gas (NG), biomass and coal; for the processes: production of synthesis gas (syngas) from GN, coal gasification and biomass gasification; and for the products: lubricating oil, diesel fuel, naphtha, methanol and ammonia. The analysis of cause-effect matrices generated the final matrix, named balance matrix, which allowed the selection of the most suitable route for the production of fuels and synthetic derivatives. Among the input studied, NG presented remarkable advantages among the others. Therefore, the process to be used should be the production of syngas from NG. Among the products considered, methanol showed the best benefits to be produced.

O objetivo deste trabalho é aplicar a metodologia do Planejamento Integrado de Recursos energéticos (PIR) dentro do ambiente corporativo. Para estudo de caso foi escolhida uma indústria de papel e celulose, por se tratar de uma das indústrias de maior consumo energético, e a região onde ela está instalada, o município de Suzano. Inicialmente, procurou-se descrever o processo produtivo em uma indústria de papel e celulose. Para este trabalho foi analisado somente os recursos do lado da oferta. Além dos recursos tradicionais, que são a caldeira de biomassa, a caldeira de gás natural/óleo combustível e as caldeiras de recuperação, foi incluída uma nova tecnologia, a gaseificação de biomassa. Foram descritas as tecnologias de gaseificação disponíveis e mostrado o seu estado da arte. Dentro dessas tecnologias, há uma aplicação que busca substituir as tecnologias atuais de caldeira de recuperação, a gaseificação de licor negro. / The purpose of this study was to apply the Integrated Resources Planning for Energy (IRP) methodology within corporate environment. A study of case of pulp and mill industry was chosen, because it is one of largest energy consumption industries, and the region that was studied was Suzano. Initially we described the industrial process of pulp and mill factory. This study we will analyze only the features of Supply Side Resources. In addition to the traditional power supplies which are biomass boiler, natural gas/fuel oil boiler and recovery boiler, we include a new technology, biomass gasification. We described the technologies available for gasification and show the state of art of this technology. Within these technologies, we have an special application the seeks to replace currently technology of recovery boiler, Black Licor Gasification.

No presente trabalho, o desempenho energético e ambiental de potencias rotas de produção de hidrogênio gaseificação da biomassa via leito fixo (LFX) e leito fluidizado (LFL) e de energia solar fotovoltaica foram estudados com base na metodologia de Avaliação do Ciclo de Vida (ACV). Após a revisão da literatura e a descrição dos procedimentos de análise, os resultados da ACV são apresentados e discutidos em termos de Demanda Acumulada de Energia (CED), Tempo de Retorno de Investimento em Energia (EPBT) e danos relacionados à Saúde Humana (SH), Qualidade do Ecossistema (QE) e Recursos Minerais e Combustíveis Fósseis (RMCF). No cômputo geral, o LFL é mais favorável para a produção de hidrogênio, embora os dois sistemas de gaseificação apresentem desempenho energético e ambiental similares. Comparativamente, o sistema fotovoltaico apresenta um EPBT maior (4,55 anos) do que os encontrados nos dois sistemas de conversão da biomassa (1,65 anos no LFL e 1,77 anos no LFX). Por outro lado, o sistema de energia solar fotovoltaico é o mais ambientalmente recomendável para a produção de hidrogênio, tendo em vista a menor contribuição em relação aos danos majoritários (saúde humana). Dentro do escopo do estudo, os sistemas avaliados apresentam mais características de complementaridade do que competição. Neste caso, enfatiza-se a importância de uma análise dos fatores econômicos e sociais pertinentes a cada país ou região, bem como dos processos posteriores de reforma e/ou purificação e eletrólise da água, considerando também o seu inteiro ciclo de vida. / In the present study, the energy and environmental performance of hydrogen potential routes biomass gasification systems by fixed bed and fluidized bed and the solar photovoltaic power plant were studied based on Life Cycle Assessment (LCA) methodology. After reviewing the literature and analytical procedures description, the results of life cycle assessment are discussed in terms of Cumulative Energy Demand (CED), Energy Payback Time (EPBT) and damages related to Human Health (SH), Ecosystem Quality (QE) and Mineral and Fossil Fuels Resources (RMCF). Although the two gasification systems have similar energy and environmental performance, the LFL is more favorable for hydrogen production. Regarding the photovoltaic system, this has a greater EPBT (4.55 years) than those found in the two systems of biomass conversion (1.65 and 1.77 years in the LFL and LFX, respectively). On the other hand, the solar photovoltaic system is the more environmentally suitable for hydrogen production, since its contribution related to human health impact is smaller than gasification systems. Within the scope of the study, the evaluated systems have more features of complementarities than competition. In this case, we emphasize the importance of analyzing the economic and social factors that are relevant in each country or region, as well as the subsequent process for hydrogen production (purification and water electrolysis) also considering the entire life cycle of systems.

Este trabalho tem como objetivo traçar um panorama geral da tecnologia de gaseificação ao longo da história. Inicialmente concebida para obter gás do carvão mineral e possibilitar uma iluminação pública mais eficiente, a gaseificação passou por várias fases. Na virada do século XIX para o XX, quando o town gas perdeu a iluminação pública para a eletricidade, a produção de gás passou a se voltar para aquecimento e cocção. Se novas possibilidades foram criadas a partir da descoberta da síntese de Fischer-Tropsch (que possibilitava a transformação do gás de síntese em líquidos que poderiam substituir combustíveis e matérias-primas para toda a cadeia petroquímica), a resolução dos problemas de logística do gás natural reduziu a importância do gás do carvão mineral também para o aquecimento e cocção. Crises de abastecimento de petróleo, o principal combustível do século XX, motivaram novas iniciativas e novas formas de utilização da gaseificação como, por exemplo, os gasogênios, que gaseificavam biomassa e carvão para movimentar veículos automotores especialmente durante a Segunda Grande Guerra. Já nos períodos de abundância de petróleo a tecnologia acabava por ser abandonada, uma vez que este era muito mais eficiente e conveniente. Na passagem do século XX para o século XXI, entretanto, as preocupações com as mudanças climáticas colocaram em cheque a contínua utilização de combustíveis fósseis entre os quais o petróleo. Nesse contexto abriu-se uma nova perspectiva para a gaseificação de biomassa, uma vez que esta, combinada com as possibilidades criadas pela síntese de Fischer-Tropsch, possibilitou a criação do conceito de biorrefinarias e de toda uma cadeia química a partir de matérias-primas não apenas renováveis, mas que também são residuais e não alimentares. Embora ainda haja desafios técnicos e, principalmente, econômicos a serem alcançados, outros desafios deste século além da questão climática -, os resíduos sólidos urbanos podem constituir-se em uma importante fonte de insumos para o processo de gaseificação. / This dissertation aims to deliver a systematic approach of the history of gasification process. Initially conceived to obtain coal gas to viabilize more efficient lighting for major cities, the gasification process has passed through several phases. During the Nineteenth Century, the town gas (the gas obtained from coal) has revolutionized night life in modern cities. At the turn of the Nineteenth Century, town gas lost public lighting to electricity, and gas from coal had to migrate to heating and cooking. New possibilities were created with the Fischer-Tropsch synthesis in the twenties. This process enabled the transformation of Syngas a product of the gasification process into any kind of hydrocarbon molecule. So, it could have been a useful substitute to oil, mainly during the oil supply crisis. The Twentieth Century was characterized by intense oil utilization in transport, mechanical forces, electricity generation and also creating products like plastic and asphalt. Gasification was seen as a very good alternative supply of raw material for these products, but in fact, the several oil supply crisis of the Twentieth Century were too short for make the gasification feasible. At the end of twentieth century another issue arose to boost gasification initiatives: climate change. Due the greenhouse effect and concerns about its consequences, researchers and companies started projects of biomass gasification to replace fossil fuels - which includes oil. So far, all these initiatives havent shown up as feasible in commercial production, but the opportunity to create a fossil oil substitute from non food raw materials still involves a lot of effort.

Power generation from biomass based renewable energy technologies is a promising option in retrofitting our dependence in conventional power generation processes. The development of any society is not possible without sustainable energy and access to energy creates that environment that allows the world to thrive. Electricity access especially in developing regions of the world is of particular interest. This work provides results on electricity efficiency, the economic feasibility and environmental impact of biomass based power technologies in small scale setting using Aspen Plus software. The power generation processes analysed on standalone basis include - micro gas turbine, gas turbine, steam turbine, Stirling engine and internal combustion engine. Some of the processes are optimized in the design to suit the specific climate and available wood waste stream in Nigeria is considered in this work. Simulation results indicate that gas engines power technologies gave a better electric performance of more than 30% with its integration with biomass gasification technology in production of fuel gas. The stirling engine power technology shows a good prospect despite its yet to be commercial status. The modification of the engine (removal regenerator) gives a better electric efficiency. Also result shows that internal combustion engine process emits more of nitric oxides compared to other technologies which create doubts over its environmental compatibility. Economic studies show that for small scale power generation, internal combustion engines and stirling engines are economic feasible. Also, steam turbine and gas turbine illustrate why they are mostly applied in medium/large scale biomass power generation specially recommended to regions where more biomass resource are produced. The micro gas turbine power technology can also be applied in small scale despite its high total investment capital. Furthermore, the study shows that about from 1.8 million tonnes per year of saw dust (wood waste) produced from lumber industries in Nigeria, about 1.3 TWh of electricity can be generated from 1000 MW power plant. Power generation via the utilization of biomass prove to be a possible path to Nigeria’s economic, social and environmental sustainability but the extent to which this can achieved is strongly dependent institutional framework, investment, incentives and information policies. / Program: Masterutbildning i energi- och materialåtervinning

Dans le cadre d’une thématique générale du Laboratoire Thermique Energétique et Procédés de Pau consacré à l’étude et à la valorisation des déchets tels que la pyrolyse, la combustion et la gazéification, la thèse se focalise sur la modélisation des phénomènes de transports de masse, de quantité de mouvement et d’énergie en milieu multiphasique multiconstituant réactif dans le cas d’un réacteur de gazéification à lit fixe. La première étape de la modélisation consiste à décrire classiquement le mouvement de chacune des phases continues par les équations de conservation de la masse, de la quantité de mouvement et de la chaleur. Bien qu’à cette échelle les mécanismes soient parfaitement décrits, le passage à la simulation impose une étape d’homogénéisation par prise de moyenne. Ce changement d’échelle, décrit dans ce travail, conduit à un système d’équations homogène à l’échelle locale. Ce modèle est appliqué au cas du procédé de gazéification de déchets de la société Europlasma nommé CHO-Power. Les simulations bidimensionnelles instationnaires du problème ont permis de mettre en lumière les différents mécanismes en présence au cours du procédé ainsi qu’un certain nombre de verrous dans l’obtention du chemin de convergence conduisant au régime permanent. / One of the thematics of the “Laboratoire Thermique Energétique et Procédés de Pau” is the study and the valorization of waste as pyrolysis, combustion and gasification for example. In this context, this work deals with modeling of heat, mass and momentum transport in a multiphase multi components reactive medium for a fixed bed gasifier. Conservation equations are first written for each phase. The macroscopic partial differential equations are expressed by integrating these microscopic conservation laws over a representative volume. This change of scale, described in this work, leads to a homogeneous system of equations. This model is applied to the case of the gasification of waste process of the Europlasma company named CHO-Power. The unsteady two-dimensional simulations of the problem allowed to highlight the different mechanisms present during the process and a number of locks in obtaining convergence path leading to the steady state.

Afin de répondre aux besoins croissants en énergie primaire, le groupe Europlasma a développé le procédé CHO-Power permettant de valoriser énergétiquement un mélange de refus de tri d’ordures ménagères et de résidus de biomasse. L’une des particularités de ce procédé est l’utilisation d’un réacteur de dégradation thermique des goudrons et des particules solides fines par assistance plasma. L’objectif de cette étude de mieux appréhender les mécanismes réactionnels mis en jeu lors de l’épuration thermique du gaz. Dans cette optique, un réacteur pilote a été dimensionné puis construit sur la plate-forme de Recherche et Développement d’Europlasma. Il a été ensuite nécessaire de modifier le schéma réactionnel permettant la modélisation numérique de la dégradation des goudrons. Ce schéma réactionnel, couplé à l’utilisation d’un logiciel de mécanique des fluides numérique, permet de représenter les processus couplés (chimie, aéraulique, transferts thermiques) se déroulant au sein du réacteur. Deux modifications importantes ont été alors apportées au modèle cinétique simplifié jusque-là utilisé : la modélisation d’une phase discrète réactive permettant de prendre en compte la gazéification des particules de résidus carbonés et l’ajout de nouvelles voies réactionnelles afin de mieux modéliser la formation des particules de suie et de ses précurseurs. À terme, la comparaison des valeurs expérimentales à celle issues de la modélisation numérique permettra de valider ou non le schéma réactionnel dans sa globalité. / In order to contest to the high world demand for primary energy, the Europlasma group developed a new process, called CHO-Power, to enhance the thermochemical potential of a mixture of urban waste and biomass residues. One of the characteristics of this process is the use of a high temperature reactor assisted by a plasma torch for tar and soots thermal cracking. The aim of this study to improve the knowledge of the global reaction mechanism involved during the thermal treatment of gas. In this context, a pilot plant reactor was designed and built on the Europlasma Research and Development Center. During this work, the reaction pathway used to represent tars cracking at high temperature has been enhanced. Coupled to a computational fluid Dynamics Software, allow simulating the complex processes occurring within the reactor (aeraulics, reaction, and heat transfer). Two major changes were made to the simplified kinetic model previously used: the modeling of a discrete and reactive phase to take into account the possible particle gasification of carbonaceous residues and the addition of new reaction pathways to enhance the modeling of the formation of soot and its precursors. The comparison between the experimental and numerical values will validate or not the global reaction scheme and will give important information about the next evolution of the tar degradation scheme.