<p>Electric arc furnace (EAF) is a furnace that utilizes electric energy and chemical energy to melt scraps and produce liquid steel. During the industrial process of EAF, an electric arc will be generated around the electrode located at the center of the furnace, and this phenomenon will generate a lot of heat. If any part of the electric arc is exposed to the freeboard region, a region above the slag layer inside the furnace, the heat emitted by this exposed arc can significantly heat on side wall temperatures, resulting in an overheating issue of side wall. Water-cooling panels (WCP) have been used to cool down the side wall, but the concentrated overheating area, may damage the water-cooling panel. In this study, a combination of slag foaming phenomenon and electric arc has been considered. A calculator is developed based on several arc models to calculate the parameters about slag foaming and arc power. The parameters can be used as input in a computational fluid dynamics (CFD) model. The commercial software, ANSYS FLUENT^®, was utilized to give a prediction of the side wall temperature distribution of an EAF. Data from the plant has been used to validate the calculation results. Furthermore, a series of parametric studies has been investigated to study the influence of operating conditions. The developed model can help to predict the risk of overheating from given electrode conditions and slag compositions.</p>

Abstract In this thesis, different spectroscopic methods are used for studying metals. Electron spectroscopy is applied for the study of binding energy shifts between atomic vapor and solid metals. Photoionization and Auger decay of high temperature aluminum vapors are investigated. Ionization of atomic chromium metal vapor by light absorption is studied with synchrotron radiation and time-of-flight ion mass spectroscopy. Optical spectroscopy is used for studying light emission from electric arc furnace plasma in experimental apparatuses developed during this work. Experimental techniques and sample preparation methods are presented. / Original papers The original publications are not included in the electronic version of the dissertation. Huttula, M., Jänkälä, K., Mäkinen, A., Aksela, H., &amp; Aksela, S. (2008). Core shell electron spectroscopy on high temperature vapors: 2s photoionization and Auger decay of atomic aluminium. New Journal of Physics, 10(1), 13009. https://doi.org/10.1088/1367-2630/10/1/013009 Huttula, M., Partanen, L., Mäkinen, A., Kantia, T., Aksela, H., &amp; Aksela, S. (2009). KLL Auger decay in free aluminum atoms. Physical Review A, 79(2). https://doi.org/10.1103/physreva.79.023412 Aksela, S., Kantia, T., Patanen, M., Mäkinen, A., Urpelainen, S., &amp; Aksela, H. (2012). Accurate free atom–solid binding energy shifts for Au and Ag. Journal of Electron Spectroscopy and Related Phenomena, 185(8–9), 273–277. https://doi.org/10.1016/j.elspec.2012.05.007 Mäkinen, A., Patanen, M., Aksela, S., &amp; Aksela, H. (2012). Atom-solid 3p level binding energy shift of transition metals Cr, Mn, Fe, Co, and Ni. Journal of Electron Spectroscopy and Related Phenomena, 185(12), 573–577. https://doi.org/10.1016/j.elspec.2012.12.006 Mäkinen, A., Niskanen, J., &amp; Aksela, H. (2012). Relative photoionization cross section of Cr atoms in the valence region. Physical Review A, 85(5). https://doi.org/10.1103/physreva.85.053411 Mäkinen, A., Niskanen, J., Tikkala, H., &amp; Aksela, H. (2013). Optical emission from a small scale model electric arc furnace in 250–600 nm region. Review of Scientific Instruments, 84(4), 43111. https://doi.org/10.1063/1.4802833

A computerized Fast Fourier Transform system has been used to analyse vibration measurements sampled from a 100-ton electric arc furnace. It has been the hypothesis that patterns in the vibration data would correlate to specific events in the electric arc furnace during the melting process. The theory was that the vibration patterns would be most powerful in multiples of 50 Hz, as the electric arcs operate with a frequency of 50 Hz. It was concluded that the multiples of 50 Hz were dominant. Investigation was made regarding how the amount of scrap affects the amplitude in the vibrations after a defined amount of energy input. It was confirmed that the intensity of the vibrations decreased with increasing mass and basket volume. Another discovery was the M-shaped pattern at the beginning of the melting process. This pattern was statistically analysed. It was found that 71 % of the 41 charges showed an M-shaped correlation. The appearance of this M-shape was analysed regarding power usage, and steel-type. It was concluded that the steel type affected the appearance of the M-shape. The occurrence of flat-bath was also investigated. The theory was that the vibration data would be fairly constant with the occurrence of flat-bath. It was discovered that the vibration data experienced a somewhat constant behaviour towards the end of the melting process in approximately 57 % of the 41 charges. Difficulties were encountered regarding detection of patterns, and correlating them to specific conditions, due to the many parameters that affect the vibration measurements from charge to charge. It was concluded that vibration analysis are unlikely to be used as an absolute way to foresee every event in the electric arc furnace during each charge. But can rather serve as a statistical tool, upon which decisions of how the melting process should be conducted could be based on.

Abstract Carbon emissions pose a serious threat to the continued survival of this planet. All sectors of society must, therefore, lower their emissions, this includes the steel industry. The production of steel is based on iron ore reduction by carbon. In an attempt to relieve the steel industry from its inherent fossil dependence an initiative called HYBRIT has been started. It aims to supplant carbon reduction with hydrogen reduction. Currently, there is no economically viable industrial production of steel that uses fossil-free hydrogen as reduction agent. In order to create economic viability for such a process work has to be conducted to innovate and optimize. This study aims to be a part of that optimization process by creating a tool for optimizing the slag system with regards to phosphorus removal. 26843 slag compositions were evaluated using modules written in “Matlab” combined with “Thermo-Calc”. 1583 possible slag compositions were found to be suitable for phosphorus removal. These compositions were then optimized after slag weight in order to minimize slag associated cost. The compositions were tested against two theoretical raw materials with varying initial phosphorus content 250 ppm and 125 ppm. It was found that the initial phosphorus concentration of the raw material has a substantial impact not only on the slag costs but also the slag praxis that should be used.

O objetivo desse trabalho foi o de obter-se fios de cobre em três composições químicas distintas da liga Cu-Mg a partir de cobre eletrolítico e de magnésio. Foram avaliadas as etapas envolvidas, começando com a fusão de botões em forno a arco na composição do eutético Cu-Mg, diluição destes botões em forno resistivo, vazamento em lingoteira de cobre, seguido de tratamento térmico de homogeneização em forno resistivo a 910 ºC por 2 h. Os tarugos foram posteriormente trabalhados mecanicamente por forjamento rotativo seguido de um passe final de acabamento por trefilação, para obtenção do fio. As análises químicas realizadas nos lingotes indicaram que a rota de preparação dos fios mostrou-se adequada aos estudos em escala de laboratório, suficiente para a confecção de fios com área de seção transversal de 4 mm2 por 10 m de comprimento, para cada composição de liga. Os fios foram caracterizados mecanicamente por ensaio de tração e de dureza após tratamento térmico de recristalização a 510 ºC por 1 h. Os fios também tiveram as condutividades elétricas medidas na condição recristalizada e os resultados foram comparados com dados experimentais da literatura. Os materiais obtidos mostraram-se adequados à utilização como fio condutor de energia elétrica. Os limites de escoamento e de resistência a tração tiveram seus valores melhorados com o aumento do teor de magnésio na liga, 11 % e 24 %, respectivamente, enquanto houve queda nos valores de condutividade elétrica para cerca de 60 % IACS (International Annealed Copper Standard). / The aim of this work was to obtain copper wires in three different chemical compositions starting from electrolytic copper and magnesium. The mains steps were evaluated, starting from the melting of small eutectic cooper-magnesium specimens in an electric arc furnace, followed by further dilution of this buttons in a resistive furnace and casting it in a copper mould. The as cast billets were homogenized in a resistive furnace at 910 ºC for 2 h. The billets were mechanically cold worked by swaging and a final drawing step to attain a round shape and a reasonable surface quality. The cast ingots chemical analysis indicated that the processing route showed to be adequate, in laboratory scale, to obtain wires with cross sectional area of 4 mm2 and 10 m in length. The wires in both conditions as cold worked and after a recovering heat treatment at 510 ºC for 1 h, were mechanically characterized by tensile testing and hardness. The wires had also the electric conductivity assessed in the recovered heat-treated state and the results were compared to the literature data. The obtained material showed to be adequate to be used as electric conductor. The yield strain and ultimate tensile strength were improved with the increasing amount of Mg in the alloy, 11 % and 24 %, respectively, while the electric conductivity decreased to 60 % IACS (International Annealed Copper Standard).

O objetivo do presente trabalho é avaliar o uso de borracha triturada de pneu como carburante substituto do coque após a fusão e durante o refino primário oxidante em um forno elétrico a arco na produção de aço 1020. Para o teste foram produzidas 40 toneladas de borracha de pneu triturado em condições granulométricas semelhantes ao coque e abastecido nos silos que alimentam injetoras que adicionaram este material durante o refino primário oxidante. No sistema existem 3 silos e 3 injetoras que são capazes de operar com vazões independentes. O silo n° 1 e o silo n° 3 foram abastecidos com borracha triturada, enquanto que o silo n° 2 foi abastecido com o coque. Testou-se durante 152 corridas situações com injeção de borracha em 4 níveis como substituto do coque: 0% de borracha (somente coque), 33% de borracha, 66% de borracha e 100% de borracha. As vazões e quantidades totais injetadas de carburante foram mantidas em relação ao processo usual. Para evitar interferências manteve-se a receita de carga fria metálica para abastecer o forno bem como os programas elétricos e químicos. Em todas as corridas testadas foram coletadas amostras do aço e da escória no momento antes do vazamento. As amostras foram analisadas através de um espectrômetro de RX. Os resultados obtidos mostraram que é possível a substituição total do coque pela borracha de pneu triturada sem incorrer prejuízos ao processo. Não se observou incorporação de Enxofre no aço, preocupação esta que existia pelo fato da borracha triturada conter teores mais elevados deste elemento em comparação com o coque. / The purpose of this research is to evaluate the use of grinded wasted rubber tires as a carbon source to substitute the coke during the refine in an Electric Arc Furnace to produce steel - grade 1020. For the tests, it was produced 40 tons of grinded rubber in similar size grains of the coke and the material was filled up inside the tanks that feeds the carbon injectors and added the carbon source during the primary oxidant refine. The system is composed by 3 tanks and 3 injectors that can be operate independent. The tank number 1 and number 3 were filled up with grinded rubber, and the tank number 2 was filled up with coke. It was tested during 152 heats 4 different levels of rubber injection to substitute coke: 0% of rubber, 33% of rubber, 66% of rubber and 100% rubber. The flow and injected quantities were kept in the same levels of the normal process. The metallic raw material and electrical and chemical profile were kept the same to avoid interferences. Samples of the steel and the slag were taken before the tap. The samples were analyzed in the RX Spectrometer. The results showed that is it possible to substitute completely the coke with rubber without causing any issues to process. The sulfur content in the rubber did not contaminated the steel, although the rubber contains higher sulfur compared to the coke.

Neste trabalho, desenvolveu-se um novo método para a detecção e classificação dos distúrbios que afetam a qualidade de energia elétrica em sistemas elétricos industriais na presença de fornos elétricos a arco. Durante o processo de fusão dos fornos elétricos a arco, ocorrem diversos eventos que afetam o sistema elétrico ao qual estão inseridos, tendo como características: forma de onda do sinal de corrente altamente desequilibradas e com grande distorção devido aos harmônicos, efeitos de cintilação; bem como afundamento e elevação nos sinais de tensão. O método ora proposto foi aplicado a sinais reais, permitindo a detecção e classificação dos distúrbios múltiplos na forma de onda do sinal de tensão, proveniente da operação dos fornos elétricos a arco. Para tal, foi usada como base do algoritmo, uma técnica baseada na Transformada Wavelet, aplicada aos sinais não-estacionários de uma instalação industrial com três fornos elétricos a arco. / A new method for the detection and classification of the disturbances that affect the electric power quality in industrial electric systems with electric arc furnaces was developed in this work. During the fusion process of the electric arc furnaces, may occur several events that affect the electric system to which it is inserted may occur, having as characteristic: waveform of the signal of current highly unbalanced and with great distortion due to the harmonic, scintillation effects; as well as sag and swell in the voltage signals.The method proposed was applied to real signals, allowing the detection and classification of the multiple disturbances in the waveform of the voltage signal originating from the operation of the electric arc furnace. For this purpose, a technique based on Wavelet Transform will be used and applied to the not-stationary signals of an industrial installation with three electric arc furnaces.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-11-29T15:35:48Z No. of bitstreams: 1 Nicole Gröff da Silva_.pdf: 8079664 bytes, checksum: 10e7ed35ed8baa348b7c5b950dea6f05 (MD5) / Made available in DSpace on 2018-11-29T15:35:48Z (GMT). No. of bitstreams: 1 Nicole Gröff da Silva_.pdf: 8079664 bytes, checksum: 10e7ed35ed8baa348b7c5b950dea6f05 (MD5) Previous issue date: 2018-07-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pesquisas científicas e tecnológicas têm indicado a possibilidade de reciclagem de inúmeros resíduos sólidos na construção civil, dentre os quais encontra-se o pó de aciaria elétrica (PAE). O PAE é originado no processo de produção de aço e classificado como um Resíduo Classe I perigoso (ABNT, 2004a). O objetivo deste trabalho foi avaliar a viabilidade técnica e ambiental do material cerâmico produzido a partir da adição de PAE em argila vermelha. A etapa metodológica da pesquisa contemplou a amostragem das matérias-primas e sua caracterização química, física, mineralógica e térmica. Além disso, a formulação e moldagem da massa cerâmica com 0, 10, 20 e 30% de PAE e a sinterização e coleta das emissões atmosféricas de processo a 750, 850 e 950°C. Por fim, foram realizados ensaios de caracterização técnica e ambiental no material obtido. Dentre os resultados encontrados, verificou-se que a argila possui como principais elementos Si, Al e K, enquanto que para o PAE os principais são Fe e Zn. Além disso, a argila possui um tamanho de partícula superior ao do PAE, que por sua vez possui partículas de formato em geral esférico e que tendem a se aglomerar. A partir do tratamento térmico das massas cerâmicas formuladas, observou-se que a adição de 10 e 20% de PAE nas temperaturas de 850 e 950°C produz material indicado para fabricação de tijolos em termos de resistência à flexão e absorção de água. Em termos ambientais, pode-se concluir que adições de até 20% de PAE a 750°C produzem materiais classificados em função do teor de Al como Classe IIA não inerte, conforme a NBR 10006 (ABNT, 2004d). Quanto às emissões atmosféricas, com exceção do teor de 30% de PAE produzido a 850°C, as demais combinações testadas estão de acordo com as normas de referência, não havendo legislação específica para esta atividade. Considerando uma visão global dos resultados obtidos, indica-se o uso de até 10% de PAE para fabricação de tijolos a partir de 850°C, prevendo-se assim sua conformidade com as normas técnicas de produtos de cerâmica vermelha. / Scientific and technological researches have been indicated the possibility of recycling several kinds of waste in construction, among which it stands out the electric arc furnace dust (EAFD). The EAFD is originated in the steelmaking process and classified as a hazardous waste (ABNT, 2004a). The aim of this research was to evaluate the technical and environmental viability of ceramic material produced from EAFD addition in red clay. The methodological stage included sampling of raw materials, its chemical, physical, mineralogical and thermal characterization. Also, the formulation and molding of compositions with 0, 10, 20 and 30% of EAFD and the sampling of atmospheric emissions from sintering at 750, 850 e 950°C. Finally, it was realized technical and environmental tests in the obtained material. Among the results, it was verified that the red clay has in its chemical composition, Al, Si and K as majoritarian elements, while EAFD has, mainly, Fe and Zn. Besides that, the red clay has larger particle than EAFD’s, which in turn has spherical particles which tends to form agglomerates. As result of the thermal treatment, it was observed that the addition of 10 and 20% of EAFD and sintering at 850 and 950°C produces a material indicated to bricks in function of its flexural strength and water absorption. In environment terms, it can be concluded that additions up to 20% of EAFD processing at 750°C produce a material classified as not inert, according NBR 10006 (ABNT, 2004d) due to its Al content. Regarding atmospheric emissions, excluded the addition of 30% of EAFD sintering at 850°C, all conditions are according to the reference norms, even though there is no specific standard to this activity. In a global perspective, it is indicated the use of EAFD up to 10% to bricks sintering above 850°C, predicting its accordance to red ceramic specifications.

Neste trabalho, desenvolveu-se um novo método para a detecção e classificação dos distúrbios que afetam a qualidade de energia elétrica em sistemas elétricos industriais na presença de fornos elétricos a arco. Durante o processo de fusão dos fornos elétricos a arco, ocorrem diversos eventos que afetam o sistema elétrico ao qual estão inseridos, tendo como características: forma de onda do sinal de corrente altamente desequilibradas e com grande distorção devido aos harmônicos, efeitos de cintilação; bem como afundamento e elevação nos sinais de tensão. O método ora proposto foi aplicado a sinais reais, permitindo a detecção e classificação dos distúrbios múltiplos na forma de onda do sinal de tensão, proveniente da operação dos fornos elétricos a arco. Para tal, foi usada como base do algoritmo, uma técnica baseada na Transformada Wavelet, aplicada aos sinais não-estacionários de uma instalação industrial com três fornos elétricos a arco. / A new method for the detection and classification of the disturbances that affect the electric power quality in industrial electric systems with electric arc furnaces was developed in this work. During the fusion process of the electric arc furnaces, may occur several events that affect the electric system to which it is inserted may occur, having as characteristic: waveform of the signal of current highly unbalanced and with great distortion due to the harmonic, scintillation effects; as well as sag and swell in the voltage signals.The method proposed was applied to real signals, allowing the detection and classification of the multiple disturbances in the waveform of the voltage signal originating from the operation of the electric arc furnace. For this purpose, a technique based on Wavelet Transform will be used and applied to the not-stationary signals of an industrial installation with three electric arc furnaces.

The thesis utilizes the analogy in dynamic equations between a mechanical and an electrical system to convert the steam-turbine, micro-turbine, wind-turbine and hydro-turbine generator mechanical model to equivalent electrical circuit models respectively. And based on the round rotor type and permanent magnetic rotor type synchronous generators¡¦ dynamic equations, as well as their electromagnetic torque equations, the equivalent electrical interface circuits were derived respectively. By using the interface circuit, the circuit model of synchronous generator and the equivalent electrical circuit model of turbine-generator mechanism can thus be combined into the electromechanical integrated circuit model (Thevenin¡¦s analogy circuit model and Norton's analogy circuit model). The electromechanical integrated circuit model is helpful for analyzing the energy conversion, power transmission and interactions between the mechanical and electrical systems for a turbine generator unit. In order to learn about these electromechanical interactions by using the proposed electromechanical integrated circuit model, the thesis has made a study on the torsional vibrations for a small gas turbine generator unit and for a large steam turbine generator unit respectively. By way of the frequency scanning and eigenvalue calculation, it is found that the torsional mode frequencies can be changed due to the electromechanical integration. Moreover, the small unit was more affected by the electromechanical integration than the large unit. Finally, we studied the effect of operations of an Electric Arc Furnaces (EAF) on torsional vibrations of a low capacity turbine generator. The electric system studied belongs to a practical steel plant in an industrial park. Based on the electromechanical integrated equivalent circuit model, a flywheel coupling shaft was designed. It is found by simulations that the coupling shaft can be quite effective in alleviating vibrations caused by the system unbalance arising from the EAF operations.