Este trabalho propõe uma metodologia para enumerar soluções, que indiquem a barra e a compensação de potência reativa necessária para o sistema elétrico sob análise, que atendam aos requisitos avaliados pela função objetivo e as restrições. Nessa alocação de compensação ótima de potência reativa, obtemos as melhores barras e configurações de potências e tecnologias de dispositivos de compensação, minimizando as perdas totais de potência ativa da rede. Em redes fracas com conversores de frequência (por exemplo, para conexão de fontes renováveis, ou interligações utilizando conversores HVDC), esta metodologia proposta busca a melhor relação de curto-circuito trifásico (SCR) no ponto de conexão do conversor de frequência, melhorando a conexão da barra de interesse. O método busca soluções para alocar um único dispositivo de compensação, e soluções alocando simultaneamente dois dispositivos. A metodologia proposta baseia-se na enumeração exaustiva das soluções, e o estudo de caso nos sistemas de 14 e 30 barras do IEEE mostrou a aplicabilidade e funcionalidade da metodologia proposta. / This work proposes a methodology to enumerate solutions, which indicate the bar and the reactive power compensation required for the electrical system under analysis, that meet the requirements evaluated by the objective function and the constraints. In this allocation of optimal compensation of reactive power, we obtain the optimal bars and technologies of compensation devices, minimizing the total losses of active power of the network. In weak networks with frequency converters (e.g. for connection of renewable sources, or interconnections using HVDC converters), the proposed methodology seeks the best threephase short-circuit (SCR) relation at the connection point, improving the connection of the new generation. The method looks for solutions to allocate a single compensation device, and solutions to allocate two devices simultaneously. The proposed methodology is based on the exhaustive enumeration of the solutions. A case study carried out in the IEEE 14 and 30 bus systems shows the applicability and performance of the proposed methodology.

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-04-07T15:02:11Z No. of bitstreams: 1 Marina Menezes de Brito.pdf: 2230882 bytes, checksum: 6d6eefed0cd352899889aef8831943e1 (MD5) / Approved for entry into archive by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-05-09T18:16:19Z (GMT) No. of bitstreams: 1 Marina Menezes de Brito.pdf: 2230882 bytes, checksum: 6d6eefed0cd352899889aef8831943e1 (MD5) / Made available in DSpace on 2016-05-09T18:16:19Z (GMT). No. of bitstreams: 1 Marina Menezes de Brito.pdf: 2230882 bytes, checksum: 6d6eefed0cd352899889aef8831943e1 (MD5) / O óxido nítrico (NO) representa cerca de 95% de todo NOx lançado na atmosfera. Estes são emitidos tanto por fontes móveis quanto por fontes estacionárias, causando problemas ambientais como chuva ácida, smog fotoquímico e depleção na camada de ozônio, o que torna a regulamentação dessas emissões cada vez mais rigorosa. Dentre as principais tecnologias para remoção dos NOx de fontes estacionárias, o tratamento pós combustão é o mais aplicado. Este pode ser feito a partir de reações de redução a nitrogênio (N2), usando gases como amônia (NH3), monóxido de carbono (CO) e hidrocarbonetos, ou de reações de oxidação a NO2 seguida de absorção. Em destaque, a redução com NH3 se mostra mais interessante, pois os produtos de reação são N2 e H2O. Neste trabalho, a redução seletiva não catalítica foi avaliada e indicou que a reação só ocorre em temperaturas acima de 600°C, justificando o uso de catalisadores em temperaturas mais baixas. Testes preliminares indicaram atividade catalítica para óxidos mistos de ferro e titânio na faixa de temperatura de 250-500°C, mas o mesmo não foi observado para os óxidos dos metais puros TiO2 e Fe2O3. Esses materiais foram comparados com o catalisador de composição semelhante ao catalisador padrão da reação (V2O5/TiO2). Com o objetivo de investigar a sinergia dos metais ferro e titânio na reação de SCR- NH3 foram preparados diferentes materiais variando razão Fe/Ti, método de síntese e precursor do titânio. A análise química das amostras mostrou pequenas diferenças na razão Fe/Ti sugerindo pequena perda de precursor de titânio e para a amostra preparada a partir de TiOSO4, foi observado enxofre residual. Os difratogramas de raios-X indicaram a formação de três fases (Fe2O3, TiO2 e Fe2TiO5) para todas as amostras. O refinamento Rietveld indicou a composição de cada fase em cada amostra. Os parâmetros de cela sofreram distorções e sugeriram substituição isomórfica de ambos os metais na estrutura do rutilo (TiO2) e da hematita (Fe2O3). As micrografias das amostras mostraram um aglomerado de partículas distintas e, a formação de poros para as amostras preparadas por combustão. A análise textural mostrou materiais com diferentes texturas e áreas superficiais na faixa de 19 a 120 m² g-1. A dessorção termoprogramada de amônia mostrou que todos os materiais adsorvem amônia, uma etapa do mecanismo da reação de SCR-NH3. Todos os materiais preparados se mostraram ativos na reação de SCR-NH3 chegando a rendimento de 100% a 500°C. Testes de estabilidade foram feitos com duas das amostras em temperaturas de 350 e 450°C e ambos os materiais se mostraram estáveis, mantendo ou aumentando o rendimento a N2. O estudo do mecanismo de reação feito por DRIFT mostrou que há maior formação de bandas relativas a adsorção de NH3 que à adsorção de NO e, portanto, o mecanismo Eley-Rideal é mais consistente para estes materiais. Este estudo ainda supõe que a presença do O2 facilita a adsorção da NH3. O catalisador preparado com TiOSO4 não desativa completamente na presença de SO2. / Nitric oxide (NO) is about 95% of all NOx released into the atmosphere. These are issued by both mobile sources and for stationary sources, causing environmental problems such as acid rain, photochemical smog and depletion in the ozone layer, which makes the regulation of these increasingly stringent emissions. Among the key technologies for the removal of NOx from stationary sources, the post combustion treatment is the most applied. This can be done from the reduction reactions of nitrogen (N2) using gases such as ammonia (NH3), carbon monoxide (CO) and hydrocarbons or oxidation reactions to NO2 followed by absorption. Featured, reduction with NH3 appears more interesting because the reaction products are N2 and H2O. In this work, the selective non-catalytic reduction was measured and indicated that the reaction only occurs at temperatures above 600 ° C, justifying the use of catalysts at lower temperatures. Preliminary tests indicated catalytic activity for mixed iron oxides and titanium in the 250-500 ° C temperature range, but the same was not observed for the oxides of metals pure TiO2 and Fe2O3. These materials were compared with the catalyst composition similar to the standard reaction catalyst (V2O5 / TiO2). In order to investigate the synergy of metals iron and titanium in the SCR-NH3 reaction were prepared different materials ranging molar ratio Fe / Ti, synthesis method and titanium precursor. The chemical analysis of the samples showed small differences in the ratio Fe / Ti suggesting little loss of titanium and residual sulfur was observed for the sample that was prepared with TiOSO4. The X- ray diffraction indicated the formation of three phases (Fe2O3, TiO2 and Fe2TiO5) for all samples. The Rietveld refinement indicated the composition of each phase in each sample. The cell parameters suggested distortion suffered isomorphous substitution of both metals in the rutile structure (TiO2) and hematite (Fe2O3). The micrographs of the samples showed an agglomeration of distinct particles and forming pores in the samples prepared by combustion. The N2 adsorption isotherms showed materials with different textures and surface areas with 19 to 120 m² g-1. The temperature programmed desorption of ammonia shows that all the materials adsorb ammonia, a step of mechanism of the SCR-NH3 reaction. All prepared materials proved active in the SCR-NH3 reaction reaching 100% yield at 500 ° C. Stability tests were performed with two samples at temperatures of 350 to 450 ° C and both were stable material while maintaining or increasing the yield of N2. Study of reaction mechanism made by DRIFT showed that there is a greater formation of bands on the NH3 adsorption when compared to the adsorption of NO and thus the Eley-Rideal mechanism is more consistent for these materials. This study also assumed that the presence of O2 facilitates the adsorption of NH3. The catalyst prepared with TiOSO4 does not deactivate completely in the presence of SO2

The road transportation is a big source for the release of NOx emissions. NOx has been confirmed to cause negative affect on the air-quality especially in the urban areas, there are therefore regulations for allowed released amount from vehicles. The most adopted technology used for the reduction of these NOx emissions from the diesel exhaust gas is the ammonium selective catalytic reduction (NH3-SCR) using a Cu-zeolite as the catalyst in the system. The SCR catalyst can be deactivated through different mechanism, whereas poisoning by sulfur has been documented to be an important factor for the deactivation. The degree of deactivation of the catalyst has been suggested to vary depending on the catalytic material and which sulfur conditions the catalyst is exposed to, where SO3 has been indicated to cause more sever deactivation compared to SO2.  The aim of this project has been to investigate the deactivation mechanism of Cu-zeolites at different SOx conditions and evaluate potential regeneration mechanism. The project was carried out by evaluating the catalysts, Cu-BEA and Cu-SSZ-13, over different reactions that occurs in the SCR system, investigating the deactivation effect caused by SO2 poisoning and the regeneration potential. The project was then continued with the focus on the Cu-SSZ-13 catalyst investigating different SOx poisoning and regeneration conditions were investigated. In order to investigate the SO3 poisoning a generator using oxidation of SO2 to SO3 was successfully build during this project.  A kinetic model over the Cu-SSZ-13 NH3-SCR reactions was also built based on literature studies and the experimental data obtained. The results from the sulfur poisoning of Cu-BEA are based on the master thesis by Maria Arvanitidou. The fresh samples Cu-Beta and Cu-SSZ-13 exhibited similar activity, with the exception of the high formation of N2O observed over Cu-Beta under SCR conditions. The SO2 causes deactivation, especially at low temperatures. Cu-SSZ-13 exhibited more loss in activity but was able to recover more through the elevated SCR regeneration steps than the Cu-Beta. When SO2 exposure was performed together with NH3, larger deactivation was observed, likely due to ammonium sulfate species formed on the surface. The ammonium sulfate species were less thermally stable than copper sulfates, making it easier to recover the loss of activity in the Cu-SSZ-13. SO3 caused a much more sever deactivation of the SCR reactions than that of the SO2 poisoning and continued to show the lowest NOx removal activity after the regeneration process.  A difference in initial deactivation and recovery of activity between standard and fast SCR reactions was observed, indicating that the different mechanisms used are affected differently by the poisoning. The kinetic model for NH3-SCR over the Cu-SSZ-13 was successfully created when compared to the experimentally obtained data.

Este trabalho propõe uma metodologia para enumerar soluções, que indiquem a barra e a compensação de potência reativa necessária para o sistema elétrico sob análise, que atendam aos requisitos avaliados pela função objetivo e as restrições. Nessa alocação de compensação ótima de potência reativa, obtemos as melhores barras e configurações de potências e tecnologias de dispositivos de compensação, minimizando as perdas totais de potência ativa da rede. Em redes fracas com conversores de frequência (por exemplo, para conexão de fontes renováveis, ou interligações utilizando conversores HVDC), esta metodologia proposta busca a melhor relação de curto-circuito trifásico (SCR) no ponto de conexão do conversor de frequência, melhorando a conexão da barra de interesse. O método busca soluções para alocar um único dispositivo de compensação, e soluções alocando simultaneamente dois dispositivos. A metodologia proposta baseia-se na enumeração exaustiva das soluções, e o estudo de caso nos sistemas de 14 e 30 barras do IEEE mostrou a aplicabilidade e funcionalidade da metodologia proposta. / This work proposes a methodology to enumerate solutions, which indicate the bar and the reactive power compensation required for the electrical system under analysis, that meet the requirements evaluated by the objective function and the constraints. In this allocation of optimal compensation of reactive power, we obtain the optimal bars and technologies of compensation devices, minimizing the total losses of active power of the network. In weak networks with frequency converters (e.g. for connection of renewable sources, or interconnections using HVDC converters), the proposed methodology seeks the best threephase short-circuit (SCR) relation at the connection point, improving the connection of the new generation. The method looks for solutions to allocate a single compensation device, and solutions to allocate two devices simultaneously. The proposed methodology is based on the exhaustive enumeration of the solutions. A case study carried out in the IEEE 14 and 30 bus systems shows the applicability and performance of the proposed methodology.

This diploma thesis deals with the issue of nitrogen oxides emissions in exhaust gases and possibilities of their reduction. The task of the thesis was analysis of systems for NOX reduction by contemporary diesel engines, design and construction of NOX reduction device for given diesel engine, then verify functionality of this system compiled from commercially available components. In the last part of thesis available measurements will be made with an analysis of achieved results.

This masters’ thesis deals with a thermal design of a draft dry bottom boiler for bituminous coal that should replace a disassembled boiler in a current boiler room. Application of SCR is intended in order to reach emission standards of NOx.

Diploma thesis deals with the exhaust system able to pass emission restrictions Stage IV. How emissions are produced as well as how could be minimized is described. Analysis of components lay out necessary to AdBlue injection is mentioned. Main part of this paper handle with given design of exhaust system combining diesel particulate filter, as well as filters required to reduce nitrogen oxides. Strength analysis covering vibrations, welds, fatigue and life is concluded. Thesis is made for Zetor Tractors a.s. purposes.

SCA Ortvikens energiavdelning har fem stycken fastbränslepannor som försörjer interna förbrukare med processånga. Bränslet är i huvudsak bark, biologiskt slam och pelletspulver. SCA är ålagda att registrera utsläpp till luft och redovisa detta enligt de i verksamhetstillståndet villkorsbelagda utsläppen samt för kväveoxid-deklaration och för handel om utsläppsrätter för CO2. Förutom verksamhetstillståndet innefattas SCA Ortviken dessutom av förordningen 2013:252 Stora förbränningsanläggningar. För att redovisa detta används miljöredovisningssystemet ”MRS” från Entric AB. Drift-och underhåll saknar i nulägen en övergripande bild över MRS vilket skulle underlätta deras arbete för att säkerställa funktion på ingående signaler och därmed minska risken för mätbortfall vilket kan förebygga höga utsläpp under produktionen i framtiden. I detta arbete har, genom flödesscheman för de mest relevanta signaler och mätvärden vad gäller utsläpp som är kopplade till MRS, kunna underlätta för processoperatörer och underhållsorganisationen att säkerställa mätfunktionen. Arbetet har dessutom, genom analys av historiska data över driften, lett till förslag på åtgärder för att minska bildandet av olika utsläpp. Arbetet har visat att det finns många enkla åtgärder som kan göras för att minska utsläppen på redan befintligt installerad teknik på pannorna, men även gett förslag på annat teknik, och hur denna kan appliceras. Arbetet har också visat på brister i den nuvarande dokumentation-och signalhanteringen i avseende att göra mätvärden synliga i processystem andra än MRS.

In the time line of world industrial age, the most important era begins in the late 18th century when the use of fossil fuels was growing intensively. This approach has continued and developed up to the 20th century. Besides, this trend has had side effects like polluting environment. Air pollution is one of the critical issues nowadays that stems from using hydrocarbon fuels. One type of the problematic compounds in polluting air is nitrogen oxides that can be produced in combustion process from engines and industrial plants. Different solutions have been suggested to remove air polluting compounds. One method for removing nitrogen oxides is using the mechanism of Selective Catalytic Reduction in silencer of engines. This method has become practical in trucks’ engines. Therefore, research on SCR chemistry is important for improving the usage of this method in removing nitrogen oxides. SCR has its own problems when used in trucks. One of the problems is formation of white clumps on pipe wall of silencers using SCR which can cause back pressure in the engines and costs a lot to remove them from engines.  This report evaluates the effect of alternative fuels on SCR chemistry .Different parameters affecting deposit formation are studied and evaluated. Ethanol is one of the controversial fuels used in engines and acetic acid is one its byproducts. Also, urea and its by products are important materials in SCR chemistry, too. Consequently, the first part of the report studies the influence of acetic acid and Ferrite steel, one of the usual steels in silencers of engines, on urea, biuret and cyanuric acid decomposition. The instruments used in the first part include TGA-DSC (Thermo Gravimetric Analysis-Differential Scanning Calorimetric) which is connected to FTIR (Fourier Transform Infrared Spectroscopy).In the second part of the report, the effect of diesel exhaust and ethanol exhaust on cyanuric acid evaporation rate is evaluated. Cyanuric acid is the main compound forming deposit in silencers. The instrument used in the second part is TGA. The third part consists surveying effect of Adblue, aqueous solution of urea, and additivised Adblue, surfactant added Adblue to improve its efficiency, in a patented rig that is scaled down of a silencer of truck. The most important result for the first part includes the effect of Ferrite steel treated with acetic acid that accelerated the decomposition of cyanuric acid. This result can be investigated more in order to be used in silencers to accelerate the decomposition rate of clumps formed. In the second part, it is found out that cyanuric acid evaporates faster under ethanol exhaust than diesel exhaust. The third part’s results shows that in the current assembly of pipes in the rig, Additivised Adblue loses its improved efficiency which is an interesting result for engine welding in order to avoid this type of connection in engines.

Deactivation of titania-supported vanadia commercial SCR catalysts exposed to flue gases from both coal and coal-biomass co-firing boilers were investigated. BET surface area and average pore diameter measurements on both fresh and exposed commercial catalyst samples indicated pore plugging occurred to exposed catalyst samples. ESEM analyses showed fouling on catalyst surface, and poison deposition on both catalyst surface and inner pores. Activity assessments of commercial monolith catalysts with various exposures (time and fuel type) indicated that catalyst deactivation involves fouling, pore plugging, and poisoning. Different mechanisms may dominate depending on exposure time, catalyst properties, and combustion environment. Better controlled lab-scale investigations involved poisoning and sulfation of SCR vanadia/titania catalysts synthesized with an incipient impregnation method. In situ FTIR spectroscopy indicate that K, Na, and Ca (among others materials) reduce, and sulfation and tungsten increase ammonia adsorption intensity on Brønsted acid sites. Activity measurements by MS showed K, Na, and Ca poison SCR catalysts, and sulfation and tungsten enhance SCR NOx reduction activity. Both the decrease and increase of catalyst activity arise from the decrease and increase of the pre-exponential factor (A) correspondingly. Moreover, the decrease of NO reduction activity from each poison are consistent with the IR peak area decrease of ammonia adsorbed on Brønsted acid site caused by the corresponding poison but not Lewis acid sites. Therefore, Brønsted acid sites participate more actively in SCR reaction than Lewis acid sites. However, Brønsted acid sites itself do not possess NOx reduction activity as indicated by zero NO conversion on 9% W/Ti which shows large amounts of Brønsted acid sites population. Therefore, dual acid (Brønsted) -redox (vanadia) sites are suggested to provide the active center during catalytic reduction cycle with weakly adsorbed or gas phase NOx reacts with surface adsorbed ammonia. In addition, in situ FTIR spectroscopy combined with XPS analyses indicate that sulfate does not form on vanadia sites but on titania sites.