Submitted by Dilene Paulo (dilene.fatima@ufcg.edu.br) on 2018-02-05T12:19:11Z No. of bitstreams: 1 JORGE lUIZ MOURA DOS SANTOS – DISSERTAÇÃO PPGEQ 2009.pdf: 1242850 bytes, checksum: 4b01984b14177e53d87f83f20fe95699 (MD5) / Made available in DSpace on 2018-02-05T12:19:11Z (GMT). No. of bitstreams: 1 JORGE lUIZ MOURA DOS SANTOS – DISSERTAÇÃO PPGEQ 2009.pdf: 1242850 bytes, checksum: 4b01984b14177e53d87f83f20fe95699 (MD5) Previous issue date: 2009 / O processo de combustão tem grande importância para o desenvolvimento industrial. Nos últimos anos o setor industrial Brasileiro vem sofrendo seguidos aumentos no preço do gás natural e a legislação ambiental é cada vez mais restritiva, principalmente no que tange a emissões atmosféricas. O setor industrial, principalmente as empresas que tem como concorrência direta os produtos importados, concorre cada vez mais com mercados competitivos sendo necessária a redução de custos variáveis de produção. Tanto do ponto de vista econômico como ambiental é fundamental o profundo conhecimento e controle das reações de combustão que ocorrem nas fornalhas de craqueamento para a adoção de medidas de maior eficiência energética que resultem um aproveitamento mais racional de energia e uma menor disposição de poluentes como, por exemplo, CO e NOx. Este trabalho apresenta uma analise metodológica estruturada para avaliar a eficiência da combustão em uma fornalha de craqueamento de 1,2 Dicloroetano pelos métodos direto e indireto, assim como as perdas térmicas na fornalha e a carga efetivamente útil para o sistema. A eficiência de uma fornalha é obtida pela determinação da percentagem da energia fornecida para a fornalha e as percentagens de perdas térmicas devido aos vários fenômenos naoperação da fornalha. / The Combustion process has great importance to the industrial development. In recent years the Brazilian Industrial sector comes suffering increases in the prices from the natural gas and the environment legislation is each more restrictive time. The sector industrial mainly the companies who have as direct competition the imported products concur each time more with competitive market being necessary the reduction of changeable costs of production. As much of the economic point of view as environment is basic the deep knowledge and control of the combustion reaction that occur in the cracking furnace for the adoption of measures of bigger energy efficient that a more rational exploitation of the energy and a lesser disposal of pollutants results as for example CO and NOx. This work presents a structuralized methodological analyzes to evaluated the combustion´s efficiency in a cracking furnace of 1,2 Ethane Dichloride for the direct and indirect method as well as the thermal losses in the furnaces and the effectively useful load for the system. The efficiency of a furnace is gotten by the determination of the percentage of the energy supplied to the furnace and the percentages of thermal losses due some phenomena in the operation of the furnace. The evaluated thermal losses in this work had been the losses of the gases of combustion, the wall of the furnace and the losses due to the fuel that did not burn. In this work also the behavior of the efficiency of the furnace with the variation of the level of air excess was evaluated for the combustion.

Made available in DSpace on 2014-10-09T12:25:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:06Z (GMT). No. of bitstreams: 1 02233.pdf: 1898081 bytes, checksum: ca8d5eb71d409e24aba2146df83dd874 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-06-11T19:30:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-08Bitstream added on 2014-06-13T20:00:02Z : No. of bitstreams: 1 sugahara_d_me_guara.pdf: 1088347 bytes, checksum: a45380105015e0a3025c75e707484f21 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esse trabalho destina-se ao estudo da relação entre as condições de operação e o nível de emissão de CO2 em um forno de soleira rotativa, a óleo, utilizado para o reaquecimento de blocos de aço carbono para forjamento de rodas ferroviárias. O foco principal foi a redução na emissão de CO2 e a possibilidade de geração de créditos de carbono. Inicialmente foram apresentadas as características do sistema de aquecimento e suas influências no desempenho geral do forjamento. Em complemento foram expostas algumas condições de emissões relacionadas ao combustível e ao funcionamento do sistema de combustão. Foram selecionados parâmetros para a correção das condições de operação e ajustados para o tipo de combustível utilizado. A verificação foi feita através de análises de atmosfera. A metodologia foi eficiente e mostrou uma redução de 0,5% na concentração de CO2 nos gases de combustão que equivale a uma redução de 3,6% na emissão total de CO2. / This work studied the relation between the operation condition and the level of CO2 emission in an oil rotary furnace used to reheat steel carbon blocks to forge rail wheels. The main focus was a CO2 reduction emission and carbon credits revenue. Initially, the heating system characteristics and its influence in the forging performance were presented. Additionally, some emission conditions related to the fuel and combustion system working were exposed. Parameters were selected to correct the operation condition and adjusted to the type of the fuel used. The results were verified by atmosphere analysis. The methodology was efficient and shows 0,5% reduction in the concentration of CO2 in the combustion gases or 3,6% reduction in CO2 total emission.

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This project was the first step in developing a control system for the open slag bath furnace at Highveld Steel, in order to maximize production levels and product quality. In this dissertation, available knowledge from literature and practical experience is included. This is then processed to propose a realistic control system with the current resources available at Highveld Steel. Through research and practical experience it is shown that these furnaces are extremely sensitive to raw material quality and consistency of decision making. This is a result of the open bath configuration that necessitates the careful control of the excess energy, and the raw material composition supplied to the furnace. Through this project it was shown that both the productivity and the product quality (vanadium recovery) can be increased by simply controlling the feed-topower ratio and correct use of correction material. This has the effect of stabilizing the process energy balance which results in smaller slag temperature variations and therefore also less product quality variability. Through controlling the feed-power-ratio, energy consumption was also shown to be reduced, since excess power is minimized without negatively impacting on productivity. In this project a proposal is made to control the flow of material between the two stages in the process, which is based on either being kiln or furnace constrained. A better tapping scheduling is also proposed, based on both material accumulations inside the furnace and the charging condition of the furnace. This results in having sufficient pressure to tap iron and slag at good rates and should also yield consistent tapping weights and add to general process stability. However, engineering availability strongly impacts on both process control and furnace productivity. Consistent availability of the furnace and its supporting systems is hence essential for optimal operation. / Dissertation (MEng)--University of Pretoria, 2009. / Materials Science and Metallurgical Engineering / unrestricted

Rapporten behandlar Kandidatarbete i maskinteknik som utfördes mot Outokumpu Stainless AB, Avesta. Syftet med arbetet var att optimera placeringen för kalkinjektionen som inte sitter optimalt placerat ur ett processoptimeringsperspektiv. Målet var att utveckla placeringen och nyttjandet av kalktillsatsen i ungen, det genom att ändra designen av valvstrukturen och kylpanelen där injektionen satt ursprungligen. Positionen för kalkinjektionen i ljusbågsugnar är normalt sett placerad i hotspotten, området i ugnen där elektronerna är närmst väggen och ger mest slitage på tegelinfodringen. För att hitta en mer optimal placering och lösning studerades befintliga placeringar hos Best in Practice, Tornios och Calverts designs anläggningar, men även ett flertal besök på Outokumpu genomfördes för att skapa en tydligare bild av processen och valvkonstruktionen. En viktig del för den här typen av projekt är konstruera lösningar och att applicera dessa på valvet med hjälp av simuleringar och 3D-modeller. På det sättet går det snabbt att testa lösningar och ge en indikation om det är något som är genomförbart eller inte. Lösningar som togs fram presenterades för Outokumpu som tog beslut om att beställa de nya kylpanelerna med den utformningen som togs fram under projektet. / This report will process a master’s thesis in mechanical engineering in cooperation with Outokumpu Stainless AB, Avesta. The purpose with this work was to optimize the position for the chalk injection which, today, is not optimized from a process position view.  The goal was to develop a position and utilize the chalk supplies and this by changing the design in the vault structure and the cooling panel where the injection originally was placed.  The position of the chalk injection in the arc furnace is normally placed in the hotspots, this is the area in the furnace where the electrodes is closest to the wall and affects the most in terms of wear of the brick lining. To be able to find a more optimal position other chalk injection designs were studied that is already in use, for example in Best in Practice, Tornios and Calverts. There were also visits at Outokumpu in Avesta to create a clearer picture of the process and the vault construction.  One important part for this project was to construct a solution and then apply this on the vault with help from a simulation and 3D-models. To be able to do this Inventor was used, the same program that Outokumpu uses. By using Inventor you can easily try out different solutions and it will give an indication if it is possible to move on with this idea or not. The solutions that were established were presented to Outokumpu who then took the decision to move on with the idea and order the new cooling panel in the design that was created throughout the project.

<p>A production Basic Oxygen Furnace installation at Dominion Foundries and Steel Ltd., Hamilton, Ontario is used to develop a method of dynamically predicting the time during steelmaking at which a specified bathcarbon content will be reached.</p><p>The carbon evolution rate is calculated from continuous stack gas analysis and flow data. This information, combined with a known bath carbon content measured shortly before the end of the blow, is used to perform carbon mass balances. Bath carbon contents, calculated from these mass balances can be expressed as a function of time by a simple updated-mathematical model which is then used to predict the end point time.</p> <p>A new technique for determining stack gas flow rates by utilizing an injected chemical tracer is evaluated.</p> / Thesis / Master of Engineering (ME)

<p> An experimental investigation has been conducted into the reduction of iron oxides under blast furnace conditions. The necessary equipment has been designed, constructed and tested, and a program of study on two types of prereduced ore materials has been completed.</p> / Thesis / Master of Science (MSc)

The reaction between carbon and iron oxide-containing slag is crucial to efficient electric arc furnace steelmaking. The reaction occurs via gaseous intermediates, and the rate of gas generation by carbon gasification is limited by the chemical reactions at the slag-gas and carbon-gas interfaces. The aim of the present study was to obtain an understanding of the gasification rate limiting factors and slag foaming behaviour that could be readily applied to industrial electric arc furnace situations. The rate of carbon gasification was measured in experimental simulations of an electric arc furnace heat with slags containing between 21.6 and 48.2 wt% 'FeO'. It was found that rate control was dominated by the carbon-gas chemical reaction. A model was developed which describes the carbon gasification rate, amount of residual carbon in the slag, gas composition, slag-gas interfacial area and bubble diameter during carbon injection into slag. The model predicts rate control by the carbon-gas chemical reaction, in agreement with experimental observations. The slag foaming behaviour was investigated, and it was found that the foaming index is a useful parameter in quantifying foam height only if void fraction is constant with respect to gas flow rate. The average bubble size was observed to be an important factor in determining foam stability, with smaller bubble size resulting in greater foam height. / Thesis / Master of Applied Science (MASc)

The Ladle Metallurgy Furnace (LMF) in secondary steelmaking processing allows (1) the adjustment of the chemical composition by ferroalloy addition, (2) temperature control by electrical reheating (3) homogenization of chemical composition by argon stirring (4) desulphurization and (5) control of inclusions produced during steel deoxidation. The solid oxide inclusions not only cause nozzle clogging during the continuous casting process and reduce production efficiency, but they are also harmful to the properties of the steel product. In the case of aluminum killed steel, calcium treatment of steel is typically employed to modify the solid alumina inclusions or magnesium aluminate inclusions to liquid or partially liquid calcium aluminates. Injected calcium in form of calcium wire creates calcium bubbles. A portion of calcium dissolves into the steel and diffuses into the steel bulk. However, during the dissolution process some of the injected calcium reacts, close to the injection plume, with dissolved sulfur and oxygen in the steel to form calcium sulfide and calcium oxide inclusions [1]. During ladle treatment of aluminum killed steel the inclusions which form initially are typically alumina. As the dissolved oxygen content of the steel is reduced to very low levels magnesium may be reduced from the slag and subsequently react with the inclusions resulting in a shift towards higher contents of MgO and formation of magnesium aluminate spinel. Magnesium may originate from the top slag, ferro alloys or refractories. Therefore, magnesium aluminate spinels are almost always present before calcium injection and any consideration of calcium treatment should also consider the modification of spinel in addition to alumina. The current work develops a fundamental kinetic model to describe the evolution of the inclusion population during ladle treatment of aluminum killed steels. The model builds on previous work in the author’s laboratory predicting the kinetics of slag metal reactions during ladle treatment and the transformation of alumina to magnesium aluminate spinel. The model addresses the modification of alumina inclusions by calcium and considers mass transfer of species to the inclusion-steel interface and diffusion within the calcium aluminate phases formed on the inclusion. The dissolution of calcium from calcium bubbles into the steel and formation of oxide and sulfide inclusions at the plume is coupled with the kinetic model for inclusion modification. It is found that rate of supply of calcium to the inclusions controls the overall rate of transformation. The inclusion-steel kinetic model is then coupled with the previously developed steel-slag kinetic model. The coupled inclusion-steel-slag kinetic model is applied to the chemical composition changes in molten steel, slag, and evolution of inclusions in the ladle. The result of calculations is found to agree well with industrial heats for species in the steel as well as inclusions during Ca treatment. The kinetic model is further extended to model the modification of spinel inclusions by calcium treatment. Coupling the model for inclusions modification to a multi component kinetic model for the slag-steel reactions in the ladle furnace allowed prediction of the change of average composition of inclusions which was subsequently verified using plant data from ArcelorMittal Dofasco operations. Good agreement between the experimental and calculated average composition of inclusions was obtained for most of the industrial heats. Finally, a sensitivity analysis of the coupled kinetic model was performed to compare the effect of the different processing conditions including sulphur content, stirring, total oxygen, slag composition and reoxidation, on the evolution path of inclusions. / Thesis / Doctor of Philosophy (PhD)