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Programação da descarga de navios graneleiros de carvão: um estudo de caso na Companhia Siderúrgica do Pecém. / Schedule for coal bulk carriers discharge: a case study at Companhia Siderúrgica do Pecém.Duarte, Carlos Henrique Azevedo 30 May 2018 (has links)
De acordo com Babu et al. (2015), o carvão mineral é um importante recurso natural devido à sua aplicação em várias atividades econômicas, como geração de energia, produção de aço, fabricação de cimento e produção de combustível líquido. Em função do custo e da baixa qualidade do carvão brasileiro (não coqueificável, na maioria das reservas, com elevado teor de cinzas e baixo poder calorífico), como apontado por Süffert (1997), as empresas brasileiras dos setores siderúrgico e termoelétrico necessitam importar este insumo, por via marítima. O desafio no planejamento da logística de suprimento desta matéria prima é garantir o abastecimento ao mínimo custo de estoque e de espera dos navios. A garantia de abastecimento passa por uma programação adequada da chegada e descarga dos navios. Quando a descarga de navios é uma operação gargalo, é necessário maior cuidado com a programação de recebimento, de maneira com que não haja atrasos, que causem a falta de produto, nem em muita antecipação, que podem significar excessivos tempo de fila para recebimento do material por falta de área para estocagem. Com o objetivo de se programar adequadamente a chegada de navios, de forma a evitar filas muito grandes e desabastecimento foi proposto um modelo de programação de chegada de navios, com base nos dados do complexo de Pecém. Este modelo proposto utilizou um buffer de tempo pré-determinado, que foi testado e validado através de simulação, com objetivo de minimizar os atrasos, de forma que possam ser absorvidos por um estoque de segurança, e as antecipações, de forma que não haja risco de falta de área de estocagem. / According to Babu et al. (2015), coal is an important natural resource due to its application in various economic activities, such as power generation, steel production, cement manufacturing and liquid fuel production. Due to the cost and low quality of Brazilian coal (not coking, in most reserves, with high ash content and low calorific value), as pointed out by Süffert (1997), Brazilian companies in the steel and thermoelectric sectors need to import this input, by sea. The challenge in planning the logistics of supply of this raw material is to guarantee the supply at the minimum cost of inventory and waiting of the ships. The supply guarantee is subject to adequate scheduling of arrival and unloading of ships. When ship unloading is a bottleneck operation, greater care is required with the scheduling of receipt, so that there are no delays, which cause the lack of product, or in much anticipation, that can mean excessive queue time for receiving the shipment material for lack of storage area. In order to properly program, the arrival of ships, in order to avoid very large queues and shortage, a model for the arrival of ships was proposed, based on data from the Pecém complex. This proposed model used a pre-determined time buffer, which was tested and validated through simulation, in order to minimize the delays, so that they can be absorved by a security stock, and the anticipations, so that there is no risk lack of storage area.
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Estudo exploratório no desenvolvimento de novos produtos em empresas do segmento de aços planos do setor siderúrgico: uma abordagem no projeto do processo. / Study research of the process project of new product development process in a Brazilian steel industry.Varandas Junior, Angelo 14 May 2008 (has links)
A demanda pela introdução de novos produtos tem sido intensificada no setor siderúrgico, justificando uma preocupação maior com a eficiência e a eficácia do Processo de Desenvolvimento de Produtos (PDP), cujo desempenho depende de vários fatores relevantes citados na literatura. No caso da indústria siderúrgica, um fator relevante é o projeto do processo, não somente pela característica de ser um processo contínuo mas também por, geralmente, envolver investimentos significativos na preparação da produção. Nesse contexto, o presente trabalho tem como objetivo realizar uma análise exploratória da fase de projeto do processo no desenvolvimento de novos produtos em duas unidades de análise do setor siderúrgico. Pretende-se, por meio da abordagem de estudo de caso, identificar práticas organizacionais, com base na literatura, focando na parte do desenvolvimento industrial e suas respectivas interfaces organizacionais, envolvendo as áreas de marketing, engenharia do produto e manufatura. Também é abordado a forma de integração dos times multidisciplinares, a tomada de decisão e os critérios utilizados para avaliação dos resultados do processo de desenvolvimento de produtos. O trabalho conclui que as empresas analisadas utilizam-se de práticas que estruturam o PDP e a integração interfuncional das áreas envolvidas é o que destaca-se como fator de sucesso na condução do desenvolvimento de novos produtos. / The demand for introducing new products has intensely increase in the metal industry. This justifies a growing concern with effectiveness of New Product Development (NPD) process, from which the performance depend on various relevant factors from the literature. In the case of the metal industry, one of the relevant factors is the manufacturing process design not only because is a continuous process but also because it involves significant investments to prepare production. In this context, this paper aims at performing a exploratory analysis of process design stage in two industrial units from metal industry. It intends to identify organizational practices e their respective interfaces, involving areas of marketing, product engineering and manufacturing. It also deals with the way multifunctional teams are integrated, decision making process, and criteria used to evaluate the results from NPD. The paper concludes that the two companies adopt organizational practices that create a framework for NPD and the integration of functional areas is one of the success factor for developing new products.
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Análise da segmentação tecnológica dos mercados da indústria siderúrgica no Brasil / Analysis of the technological segmentation in the steel industry markets in BrazilCarvalho, Thais Hortense de 20 September 2012 (has links)
O objetivo desta dissertação é analisar a evolução, principalmente nas últimas três décadas, e a configuração atual da indústria siderúrgica no Brasil sob a ótica do paradigma estrutura-conduta-desempenho (ECD), desenvolvido por Joe Bain, e das teorias de estrutura de mercado (em especial das teorias de submercados e de rotas tecnológicas) de John Sutton (1991 e 1998). Pretende-se elucidar as seguintes indagações: o por quê das usinas integradas se manterem no Brasil frente à ascensão das aciarias elétricas (mini-mills) que ocorre no cenário mundial? Qual é a evolução tecnológica dessa indústria e seus impactos sobre sua estrutura? E, por fim, quais são as razões para o uso tanto de carvão vegetal quanto de carvão mineral na produção de aço bruto em grande escala no Brasil, mas não em outros países? Os dois arcabouços teóricos considerados auxiliam na explicação de na indústria siderúrgica do Brasil haver dois submercados independentes que se diferenciam por suas rotas tecnológicas (usinas integradas versus usinas semi-integradas) e por sua classe de produtos (aços planos versus aços longos). Sob a ótica da teoria de Sutton (1998) ainda é possível fazer algumas inferências quanto à tomada de decisão em nível da empresa, a qual se depara com duas estratégias distintas: a de escalada e a de proliferação. A primeira diz respeito ao montante ao ser investido em P&D e a segunda se refere em quantas trajetórias e diferentes grupos de produtos a empresa irá atuar. Diante dessa segmentação da indústria buscou-se, a partir de análise econométrica, considerando os anos de 1996 a 2009, fundamentar as premissas de que tais submercados (aços longos versus planos) têm dinâmicas distintas nas relações entre concentração e investimentos, sendo possível identificar relação causal positiva entre investimentos em tecnologia e concentração na produção, principalmente no submercado produtor de aços longos, ou seja, à medida que aumentam os investimentos em tecnologia, a indústria tem sua estrutura alterada, passando a integrar suas rotas tecnológicas e, consequentemente, elevando a concentração do mercado. Já no submercado de aços planos, fica ilustrada a maturidade deste segmento da indústria siderúrgica no Brasil, com a concentração sendo marginalmente reduzida diante de variações no tamanho do mercado e nos investimentos. Além disso, os resultados econométricos mostram que, em ambos os submercados analisados (aço planos e longos), o papel do BNDES não foi fundamental em afetar a concentração no período de 1996 a 2009, apesar de ter tido esse papel em anos anteriores. / The objective of this dissertation is to analyze the evolution of the steel industry, mainly in the last three decades, and its recent configuration in Brazil under structureconduct- performance paradigm and Sutton\'s theories. It is aimed to answer some questions, such as: why the integrated mills still exist in Brazil as the mini-mills are surging in the world scenario; what is this industry technology evolution and how does it affect the industry structure? And so far, which are the main reasons to the existing of steel mills based on charcoal and coal at the same time, rather than in other countries? The two theoretical frameworks interact in the explanation of the existing of two independent submarkets in the steel industry in Brazil that are distinguished by their technological trajectories (integrated versus mini-mills) and by their list of products (flat versus long steel). From the Sutton\'s theory perspective, it is still possible to highlight some topics related to the firm decisionmaking level, which is faced with two distinct strategies: the escalation and the proliferation parameters. The first is related to the amount to be invested in R&D and the later refers to how many trajectories and groups the company will operate. Based on econometric analysis, in the time period from 1996 to 2009, are valid the assumptions that these submarkets have different dynamics in the relationship between concentration and investments. Also it is possible to identify positive causal effects concerning technology investments and industry concentration mainly on the long steel submarket, reflecting that as investments are increased, the industry structure is amended to integrate their technology trajectories and thus increasing industry concentration. About flat steel submarket it is showed the maturity of this segment as the concentration is marginally reduced in response to variations in market size and investment. Furthermore, in both submarkets (flat and long steel) it is evident that the BNDES\'s role was not crucial in affecting the concentration in the time period from 1996 to 2009, despite having had this role in previous years.
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Automação no controle do tempo de coqueificação em baterias de coque-siderurgia. / Automation of control in coking time in coke oven steel industry.Bueno, Nilson Magalhães 04 June 2012 (has links)
Este trabalho apresenta a arquitetura de hardware, software e os resultados da implantação de um sistema automação industrial em ambiente siderúrgico, especificamente nas Baterias de Coque do grupo Usinas Siderúrgicas de Minas Gerais S/A Usiminas, precisamente na Usina de Cubatão, localizada no município de Cubatão, estado de São Paulo - Brasil. O sistema de automação monitora em tempo real o processo de coqueificação através da obtenção da temperatura na exaustão dos gases do processo de aquecimento do carvão mineral. O objetivo é estabelecer a relação da temperatura dos gases de exaustão, proveniente do aquecimento do carvão mineral versus a determinação do tempo ideal para o respectivo desenfornamento. O ganho de produção gerado pela implantação deste sistema é apresentado ao final deste trabalho. / This work presents the architecture of hardware, software and the results of implantation of a steel industrial automation environment, specifically in the group of Coke Drums Steel Units of Minas Gerais S/A - Usiminas, precisely in Cubatão Plant, located in Cubatão, state of Sao Paulo - Brazil. The automation system monitors the real time coking process by raising the temperature in the exhaust gases of the heating process the coal. The aim is to establish the relationship between the temperatures of the exhaust gases, from the heating coal versus determining the optimal time for the respective furnace charging. The gain in output generated by the deployment of this system is provided at the end of this work.
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O processo de reestruturação da siderurgia mundial e brasileira: o caso da Companhia Siderúrgica Nacional / The process of restructuring of the Worldwide and Brazilian ironworks industry: the case of National Ironworks CompanyPoso, Antonio Toledo 17 December 2007 (has links)
Esta pesquisa analisa o processo de reestruturação do setor siderúrgico mundial e brasileiro após os anos da década de 1990, o mesmo está representado pela internacionalização das empresas do setor, com a formação de grupos multinacionais, via fusões e aquisições, sendo impulsionado pelo processo intenso de privatizações, além da nova divisão internacional do trabalho com o crescimento da produção de aço dos países subdesenvolvidos, principalmente os asiáticos. Nesse sentido, buscamos analisar o comportamento da siderurgia nacional e, especialmente o da Companhia Siderúrgica Nacional (CSN) nessa nova conjuntura mundial, assim como, as suas conseqüências para a sócio-espacial brasileira. Podendo-se observar dois cenários possíveis: A desnacionalização dos ativos internos do setor siderúrgico nacional ou a inserção ativa do país nesse processo mundial de reestruturação. / This research analyzes the process of restructuring of the Worldwide and Brazilian Worldwide and Brazilian industry sector after 90\'s, the same has been represented by the internationalization of companies in the sector, with the formation of multinational groups, via mergers and acquisitions, which have been pushed by the intense process of privatization, in addition to the new international division of labor with the growth of steel production of the developing countries, especially the Asians. Thus, we seek to analyze the behavior of the domestic ironworks industry and especially the National Ironworks Company\'s one (CSN) in this new worldwide conjecture, as well as their consequences to the Brazilian social space. It could be observed two possible scenarios: The denationalization of the domestic assets of the national ironworks sector or the active insertion of the country in this global restructuring process.
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L’Europe et l’acier (1929-1939). L’invisible république des maîtres de forges au temps des cartels : mythes et réalités / Europe and Steel (1929-1939). The Invisible Republic of Steelmakers in the time of Cartels : Myths and FactsFeltes, Paul 15 October 2016 (has links)
Fondée en 1926, la première Entente internationale de l’acier (EIA) était impuissante à contrôler le développement de nouvelles capacités de production dans les pays membres. Les groupes sidérurgiques nationaux réunis dans l’EIA se partageaient des quotas de production. Fin 1929, les maîtres de forges sont convaincus que l’EIA ne peut survivre qu’en passant à une réglementation des exportations. Ils lancent l’entreprise des Comptoirs internationaux d’exportation dont la mise en route s’avère aussi difficile que leur fonctionnement ultérieur. Ils échouent après quelques mois seulement (été 1930). En mars 1931, la première EIA cesse de fonctionner. On assiste alors à un déchaînement sans précédant de la concurrence. Les prix s’effondrent. Les dirigeants des firmes sidérurgiques cherchent alors le salut dans une nouvelle entente internationale. Les tractations aboutissent à la création de la seconde EIA (février 1933) qui, à l’opposé de la première, est axée sur un partage des seules exportations. Elle est coiffée d’une demi-douzaine de Comptoirs de vente internationaux qui règlementent les ventes à l’exportation. En même temps, on note une tendance très nette à la protection mutuelle des marchés intérieurs au sein de l’EIA. Le dépouillement d’une documentation abondante et inédite nous a permis d’analyser le dynamisme interne, les effets et les limites de l’EIA au cours des années trente. / The International Steel Cartel (ISC), founded in 1926, was unable to control the development of production capacity in the member countries. The steelmakers, who were gathered in the ISC, shared production quota. At the end of 1929, steel producers were convinced that the ISC could only survive by changing over in order to regulate exports. The steel manufacturers of Germany, France, Belgium, Luxembourg and the Saar decided to set up provisional international export syndicates for single products. These export syndicates did not achieve their aim. In March 1931, the ISC ceased to operate so that we are witnessing an outburst of the competition. Prices collapsed. The steel managers were seeking salvation in a new international agreement. The negotiations succeeded in the creation of the second ISC (1933), which, contrary to the first one, was centred on sharing of only exports. It was topped by half a dozen international syndicates, which regulated export sales. At the same time, we can see a very clear trend towards the protection of the internal markets within the ISC. The analysis of new archives allows us a better understanding of the internal dynamism, the effects and limits of the cartel during the thirties.
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Automação no controle do tempo de coqueificação em baterias de coque-siderurgia. / Automation of control in coking time in coke oven steel industry.Nilson Magalhães Bueno 04 June 2012 (has links)
Este trabalho apresenta a arquitetura de hardware, software e os resultados da implantação de um sistema automação industrial em ambiente siderúrgico, especificamente nas Baterias de Coque do grupo Usinas Siderúrgicas de Minas Gerais S/A Usiminas, precisamente na Usina de Cubatão, localizada no município de Cubatão, estado de São Paulo - Brasil. O sistema de automação monitora em tempo real o processo de coqueificação através da obtenção da temperatura na exaustão dos gases do processo de aquecimento do carvão mineral. O objetivo é estabelecer a relação da temperatura dos gases de exaustão, proveniente do aquecimento do carvão mineral versus a determinação do tempo ideal para o respectivo desenfornamento. O ganho de produção gerado pela implantação deste sistema é apresentado ao final deste trabalho. / This work presents the architecture of hardware, software and the results of implantation of a steel industrial automation environment, specifically in the group of Coke Drums Steel Units of Minas Gerais S/A - Usiminas, precisely in Cubatão Plant, located in Cubatão, state of Sao Paulo - Brazil. The automation system monitors the real time coking process by raising the temperature in the exhaust gases of the heating process the coal. The aim is to establish the relationship between the temperatures of the exhaust gases, from the heating coal versus determining the optimal time for the respective furnace charging. The gain in output generated by the deployment of this system is provided at the end of this work.
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Conversão termoquímica do resíduo do triturador de sucata (RTS) de uma siderúrgicaPerondi, Daniele January 2017 (has links)
Diferentes resíduos são gerados pelas indústrias siderúrgicas, dentre eles o resíduo dos trituradores de sucata (RTS). O destino mais utilizado para o RTS pelas indústrias siderúrgicas brasileiras é o aterro de resíduos industriais. A pirólise se apresenta como uma alternativa para o reaproveitamento do RTS. O objetivo deste trabalho foi avaliar o efeito de diferentes parâmetros operacionais sobre as propriedades e o rendimento dos produtos do processo de pirólise do RTS para fins de um posterior aproveitamento. Um reator de pirólise de leito fixo foi utilizado e as seguintes variáveis foram testadas fazendo-se uso de um planejamento experimental 2k: temperatura (500, 600 e 700 ºC), taxa de aquecimento (5, 20, 35 ºC/min), vazão de gás inerte (N2) (0,03, 0,44 e 0,76 L/min) e razão CaO/RTS (0, 1 e 2). A utilização de uma taxa de aquecimento menor, associada a presença de CaO, resultou nos maiores rendimentos de gás não-condensável (> 50%). O poder calorífico deste gás, aumentou com o incremento da razão CaO/RTS. Este aumento foi atribuído a captura in situ do CO2. A utilização de uma vazão maior de gás inerte, também favoreceu o aumento do poder calorífico do gás não-condensável. Os maiores valores obtidos (25 MJ/Nm3) são apreciáveis, considerando o poder calorífico de outros combustíveis. Os maiores rendimentos de char (> 24%) foram obtidos nos experimentos com a utilização de uma temperatura menor, associada a ausência de CaO. A utilização de uma taxa de aquecimento mais elevada resultou em maiores rendimentos de voláteis condensáveis. Os menores rendimentos de voláteis condensáveis foram obtidos quando a vazão de inerte foi menor. Também foi possível verificar que, houve um aumento do rendimento de voláteis condensáveis com a presença de CaO para a temperatura de 700 ºC. Este comportamento foi atribuído ao maior rendimento global de estireno nas referidas condições operacionais. O rendimento global de 2,4-dimetil-1-heptano também apresentou comportamento semelhante ao observado para o rendimento de voláteis condensáveis, indicando que o AlCl3 pode ter atuado como catalisador da pirólise do PP presente no RTS. Com o aumento da razão CaO/RTS, houve uma redução da concentração de CO2. A redução da concentração de CO2 na presença de CaO está associada a formação de CaCO3. A retenção de cloro no char foi mais elevada nos ensaios conduzidos na presença de CaO. Verificou-se uma redução da retenção de cloro no char com o aumento da temperatura para os ensaios conduzidos na presença de CaO. Uma diminuição da retenção de metais no char foi verificada nos experimentos conduzidos com CaO para os seguintes metais: Co, Cu, Cr, Fe, Ni e Zn. A remoção do cloro permitiria conduzir o processo de pirólise a temperaturas mais elevadas, aumentando a Eficiência Energética mínima (EE) do processo. Desta forma, fica clara a necessidade da remoção do cloro do RTS antes do processo de pirólise, pois a partir disto o uso do CaO contribuiria para o aumento da EE e da retenção de metais no char, e consequentemente da desejabilidade global. / Different wastes are generated by steel industries, among them the shredder residue (SR). The most commonly used destination for SR by Brazilian steel industry is the landfill of industrial waste. The pyrolysis can be considered a solution to this problem. The aim of this work was to evaluate the effects of different operating parameters upon the properties and yield of the SR pyrolysis process products for later use. A fixed bed pyrolysis reactor was used and the following variables were tested using a 2k experimental design: temperature (500, 600 and 700 ºC), heating rate (5, 20, 35 ºC/min), flow rate of inert gas (N2) (0.03, 0.44 and 0.76 L/min) and CaO/SR ratio (0, 1 and 2). The use of a lower heating rate, associated with the CaO presence, resulted in higher yields of non-condensable gas (> 50%). The calorific value of this gas increased with the growth of the CaO/SR ratio. This increase was attributed to an in situ CO2 capture. The use of a higher flow rate of inert gas also favored the increase in the calorific power of the non-condensable gas. The highest values (25 MJ/Nm3) are appreciable considering the calorific value of other fuels. The highest char yields (> 24%) were obtained in the experiments using a lower temperature associated with the absence of CaO. The use of a higher heating rate resulted in higher yields of condensable volatiles. The lower yields of condensable volatiles were obtained when the inert flow rate was lower. It was also possible to verify that there was an increase in the condensable volatiles yield with the CaO presence at a temperature of 700 ºC.This behavior was attributed to the higher styrene overall yield under these operating conditions. The 2,4-dimethyl-1-heptane overall yield also presented a similar behavior to that observed for the condensable volatiles yield, indicating that the AlCl3 may have acted as a catalyst for the PP pyrolysis present in the SR. With the increase in the CaO/RTS ratio, there was a reduction in the CO2 concentration. The CO2 concentration reduction in the CaO presence is associated with the CaCO3 formation. The chlorine retention in the char was higher in the experiments conducted with CaO presence. A reduction in the chlorine retention in char was observed with increasing temperature for the experiments conducted with CaO presence. A decrease in metal retention in the char was verified in the experiments conducted with CaO for the following metals: Co, Cu, Cr, Fe, Ni and Zn. Chlorine removal would allow the pyrolysis process to be conducted at higher temperatures, increasing the minimum energy efficiency (EE) of the process. Therefore, it is clear the need to remove chlorine from the SR before the pyrolysis process, since, the CaO use would contribute to the EE increase and the retention of metals in the char, and consequently the global desirability.
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L’armure du XIIIe au XVIIe siècle en Europe : une approche matérielle. Production, nature et circulation du métal / Armor in Europe between the 13th and the 17th Century : a material approach. Metal production, nature and exchangesBerard, Emilie 29 June 2019 (has links)
Ce projet s’intéresse à un objet particulier : l’armure. Celle-ci, dont la fonction première était de protéger le combattant, s’est adaptée entre le XIIIe et le XVIIe siècle aux bouleversements qu’ont connu les pratiques de guerre et l’organisation des armées dans cette période. L’armure pouvait aussi avoir une autre fonction, celle de distinguer socialement son porteur. Ainsi, à la fin du Moyen Âge l’armure est à la fois un objet de grande consommation et d’usage courant mais également un produit de luxe. Sa fabrication, dominée par différents centres de productions internationaux comme les villes Milan et Nuremberg, demandait un savoir-faire spécifique pour travailler et mettre en forme le métal.Dans le but d’éclairer d’une part les techniques et savoir-faire anciens, d’autre part la circulation et les échanges dans l’espace européen, ce projet aborde l’étude de l’armure par sa matérialité, en mettant en œuvre une approche archéométallurgique. Un corpus spécifique, de plus d’une centaine d’objets, caractéristique de l’évolution de l’équipement défensif des combattants mais également des grands centres de production européens a ainsi été constitué. L’analyse du métal a permis de déterminer la nature des matériaux employés ainsi que les techniques de fabrication de ces objets. L’étude des inclusions non métalliques a quant à elle permis de discuter de l’origine géographique du métal utilisé pour la fabrication des pièces.De façon générale, les résultats ont montré l’emploi d’alliages de natures variées, parfois très hétérogènes pour réaliser les plates d’armures. Néanmoins en moyenne le métal employé possède une dureté proche de celle d’un acier homogène à 0,4-0,5% de carbone. Les alliages trempés de dureté élevée demeurent très minoritaires dans le corpus étudié. Des spécificités ont néanmoins été relevées, comme l’utilisation d’un matériau spécifique, associant plusieurs feuilles de métal aux propriétés différentes qui pouvait offrir à l’armure de meilleures propriétés défensives. Les informations acquises ont également permis d’étudier les pratiques mises en œuvre par les armuriers que ce soit pour la fabrication d’une armure complète, la production massive de pièces en « série », ou issues d’un même atelier. Les résultats relatifs à la nature et au travail du métal nous ont ainsi amené à questionner le rôle du maitre armurier qui signait les objets et la signification de cette signature pour un atelier. / The project focuses on a specific object: armor. Between the 13th and early 17th centuries, war practices have undergone major changes, both on the technological level, as well as the organizational one. Accordingly, defensives arms were adapted to the new needs in order to protect their owners. Armor was also in some cases a mark of social distinction. Thus, at the end of the Middle Ages, armor was both an object for everyday military use, massively produced, and a luxury attire. Its fabrication was dominated by several prestigious European centers of production like Milan and Nuremberg and required specific technical skills to shape the metal.In order to shed light on some of the techniques and ancient skills, along with the circulation and exchanges in the European space, this project addresses the study of armor through its materiality, by implementing an archeometallurgical approach. A specific corpus of over a hundred artefacts was collected, characteristic of the evolution of the defensive equipment of the fighters but also of the great European centers of production. Physicochemical analysis of the metal can decipher its nature and reveal the technical skills of the craftsmen. Non metallic phases analysis has allowed to test hypotheses on the provenance of the materials employed.Overall, the results showed the use of alloys of varying nature, sometimes highly heterogeneous, to realize the plates of armor. However, on average the metal employed has a hardness close to a homogeneous steel with 0.4-0.5% carbon. Hardened alloys of high hardness remain very minor in the studied corpus. Specificities were nevertheless noted, such as the use of a specific material, combining several sheets of metal with different properties that could offer better defensive properties. The information acquired also allowed to study the workshop practices implemented by the armorers, whether for the manufacture of a complete set of armor, the mass production of "serial" pieces, or those originating from the same workshop. The results relating to the nature and hammering of the metal have led us to question the exact nature of the intervention of the master armorer who signed the artefact and the significance of the signature of a workshop.
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Advanced Solid Biofuel Production via the Integration of Torrefaction and Densification and its Characterization for the Direct Coal Substitution in Energy Intensive IndustriesGaudet, Peter George 19 November 2019 (has links)
The greatest political, scientific, and engineering challenge of the 21st century is finding a viable solution to limit anthropogenic greenhouse gas emissions (CO2) to curb the effects of global climate change. All sectors of society need to contribute to alleviate this problem, but industrial operations must play a significant leadership role. Some of these industries include: metallurgy, cement, power, agriculture and forestry. In particular, the iron/steel, cement, and power generation industries use coal on account of its high energy density among solid fuels. Coal combustion yields 720 tonne CO2/GWh, and produces fine particulates, sulphur and nitrous oxides, along with excess CO2 contributing to climate change. In comparison, biomass (such as agricultural and forestry residues) has a solid fuel rating of 25-100 tonne CO2/GWh; therefore, biomass fuels are considered more sustainable since the living biomass consumed CO2 in the early part of its life cycle. However, biomass has significant industrial shortcomings for its use as fuel at large scale, including low energy content, density, and hydrophobicity relative to coal. In short, biomass fuels cannot be substituted without major infrastructure changes which add economic penalties that industry is currently unwilling to absorb.
Biomass upgrading routes were considered in this thesis. These include densification, torrefaction, and integrated torrefaction and densification (ITD). The first half of the methodology involved converting woody biomass (willow residue and poplar bark), agricultural residue (switchgrass plants), and pulp mill waste via a single pellet/briquette press at different densification temperatures and pressures. The second half of the methodology involved product characterization of each batch of pellets and briquettes. In this work, pellets and briquettes were tested for physical characteristics (density and durability), chemical differences (energy content and hydrophobicity), and transport phenomena characteristics (drying profiles).
First, results showed that extrusion of torrefied biomass at 300°C with an estimated pressure of 10 MPa creates partially formed pellets from agricultural residues. Using the concept of ITD (temperature range 220-325°C and pressure range 40 and 215 MPa), the density was found to be 1000-1250 kg/m3 for pellets and briquettes. The degree of compression from the loose biomass was on the order of 3-10 which corresponds with theoretical expectations. Material density increased with increasing pressure. The solid yield of pellets and briquettes decreased with increasing temperature, and results aligned with micro-scale thermogravimetric analysis. The larger ITD briquettes (produced at T = 325°C, P = 40 MPa) were evaluated for calorific value and found to fall in the lignite classification (O/C < 0.4 and H/C < 1.2) on a van Krevelen diagram. The resulting ITD pellets and briquettes were found to have a durability similar to commercial materials (durability > 97%), and to be more hydrophobic (8 wt% moisture absorption compared to 35 wt%). The drying time of ITD materials was faster than commercial torrefied briquettes, with an effective diffusivity of 1.5×10-6 m2/s compared to 7.3×10-9 m2/s likely because of a smaller pore volume in ITD briquettes. Further pilot scale studies would help improve the ITD methodology and make the process more appealing for the replacement of coal fuels.
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