Waste-fired boilers suffer severely from corrosion of critical components such as superheater tubes. In this work the high temperature corrosion of candidate superheater alloys have been investigated by detailed laboratory studies and controlled field exposures in full-scale boilers. In a laboratory study the detrimental effect of gaseous hydrochloric acid (HCl) on three  different ground surface and preoxidised austenitic stainless steels was investigated. Exposures were conducted in an environment comprising N2-10O2-5H2O-0.05HCl at both 400 °C and 700 °C. A positive effect of preoxidation is evident when the alloys are exposed at 400 °C. Oxide layers formed during preoxidation effectively suppress chlorine ingress and lower the corrosion rate for all three materials while accelerated corrosion and chlorine accumulation at the metal/oxide interface is detected for ground surface specimens. The positive effect of preoxidation is lost at 700 °C and corrosion resistance is dependent on alloying level. At 700 °C metal chloride evaporation contributes significantly to the material degradation. Based on the results, high temperature corrosion in the presence of gaseous HCl is discussed in general terms.  In two different waste-fired boilers measures for counteracting superheater corrosion were investigated. In a grate-boiler the deposit formation and high temperature corrosion of some candidate superheater materials were studied. Metal loss measurements showed unacceptably high corrosion rates for the lower alloyed ferritic steels 13CrMo44 (Fe-1Cr-0.5Mo) and HCM12A (Fe-11Cr-2W), as well as for the austenitic Super 304 (Fe-18Cr-9Ni-3Cu). The corrosion attack for these alloys was manifested by the formation of mixed metal chloride/metal oxide scales. A different type of behaviour was seen for the higher alloyed austenitic steels and nickel-base alloys, which were able to form a chromium-enriched oxide next to the metal. However, the alloys suffered from localised pitting attack. Since analyses of the deposit revealed appreciable amounts of low melting salt mixtures such as ZnCl2-KCl, PbCl2-KCl, FeCl2-KCl and NaCl-NiCl2, oxide dissolution in these molten salts is the probable reason for pitting attack. In a waste-fired boiler ammonium sulphate solution was added to the flue gas and the effect on flue gas and deposit composition was evaluated. It was evident that the sulphur-rich additive reduced the amount of alkali chlorides in both the flue gas and the deposit. Results also indicated that the initial corrosion rates were lowered with the use of ammonium sulphate. It was concluded that using the additive could be a possible strategy for changing the flue gas chemistry so that superheater corrosion is mitigated. / <p>QC 20110414</p>

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The supply and demand situation is crucial for the oil and gas industry during the first half of the 21st century. For the future, we will see two trends going in opposite directions: a decline in discoveries of conventional oil and gas reservoirs and an increase in world energy demand. Therefore, the need to develop and produce unconventional oil and gas resources, which encompass coal-bed methane, gas-shale, tight sands and heavy oil, will be of utmost importance in the coming decades. In the past, large-scale production from tight gas reservoirs occurred only in the U.S. and was boosted by both price incentives and well stimulation technology. A conservative study from Rogner (1997) has shown that tight gas sandstone reservoirs would represent at least over 7,000 trillion cubic feet (Tcf) of natural gas in place worldwide. However, most of the studies such as the ones by the U.S. Geological Survey (U.S.G.S.) and Kuuskraa have focused on assessing the technically recoverable gas resources in the U.S. with numbers ranging between 177 Tcf and 379 Tcf. During the past few decades, gas production from tight sands field developments have taken place all around the world from South America (Argentina), Australia, Asia (China, Indonesia), the Russian Federation, Northern Europe (Germany, Norway) and the Middle East (Oman). However, the U.S. remains the region where the most extensive exploration and production for unconventional gas resources occur. In fact, unconventional gas formations accounted for 43% of natural gas production and tight gas sandstones represented 66% of the total of unconventional resources produced in the U.S. in 2006. As compared to a conventional gas well, a tight gas well will have a very low productivity index and a small drainage area. Therefore, to extract the same amount of natural gas out of the reservoir, many more wells will have to be drilled and stimulated to efficiently develop and produce these reservoirs. Thus, the risk involved is much higher than the development of conventional gas resources and the economics of developing most tight gas reservoirs borders on the margin of profitability. To develop tight gas reservoirs, engineers face complex problems because there is no typical tight gas field. In reality, a wide range of geological and reservoir differences exist for these formations. For instance, a tight gas sandstone reservoir can be shallow or deep, low or high pressure, low or high temperature, bearing continuous (blanket) or lenticular shaped bodies, being naturally fractured, single or multi-layered, and holding contaminants such as CO2 and H2S which all combined increase considerably the complexity of how to drill a well. Since the first tight gas wells were drilled in the 1940's in the U.S., a considerable amount of information has been collected and documented within the industry literature. The main objective of this research project is to develop a computer program dedicated to applying the drilling technologies and methods selection for drilling tight gas sandstone formations that have been documented as best practices in the petroleum literature.

[pt] Em poços de petróleo, uma boa cimentação é fundamental para garantir o suporte estrutural do revestimento e isolar o poço de águas subterrâneas. A alteração das propriedades e o surgimento de defeitos no cimento podem levar a vazamentos e danos ambientais. Durante a desativação e o abandono do poço em operações conhecidas como P&A (Plug & Abandonment), é necessário avaliar a condição do cimento assim como a identificação de possíveis defeitos. Desde 1950, ferramentas de perfilagem acústica capazes de analisar a condição do cimento vem sendo desenvolvidas e aprimoradas. As ferramentas mais famosas foram a Cement Bond logging Tools (CBT), baseada na técnica de operação CBL (Cement Bond Logging) e VDL (Variable Density Logging), e a Cement Evaluation Tools (CET). Contudo, essas ferramentas foram projetadas para operar somente em configurações com um único revestimento e sem a coluna de produção. Remover a coluna de produção é um processo caro, por isso, um desafio na indústria que permanece até os dias atuais é a criação de uma ferramenta capaz de operar em poços sem a necessidade de se remover a coluna de produção visando a redução dos custos do processo, ou em poços que possuem múltiplos revestimentos. Nos últimos anos muitas patentes e artigos tem sido publicados abordando esse mesmo tema. Este trabalho possui como motivação analisar a eficiência da utilização de ondas ultrassônicas guiadas em poços com multicamadas para detecção de defeitos presentes na camada de cimento. Para isso, primeiramente se realizou uma vasta pesquisa bibliográfica buscando identificar os tipos mais frequentes de defeitos existentes, o princípio de funcionamento das principais ferramentas comerciais existentes e os avanços das pesquisas na fronteira do conhecimento desse assunto. Modelou-se a partir da teoria de ondas e de suas equações analíticas o poço estudado, encontrando as equações de dispersão que regem o problema. Desenvolveu-se um código analítico-numérico capaz de resolver essas equações e de obter as curvas de dispersão. Além disso, analisou-se como os defeitos e suas variações afetam as curvas de dispersão, identificando os comportamentos característicos para cada caso. Posteriormente, a distribuição da energia, obtida a partir do vetor de Poynting no poço, foi usado afim de se investigar os modos que concentram a energia na camada de cimento. Para o caso sem a coluna de produção, concluiu se que os melhores modos de excitação estão em alta frequência, pois a energia se concentra no cimento. Já para o caso com a coluna de produção, encontrou-se que na frequência de 30,13 kHz a uma vagarosidade de 726,5 us/m a energia está praticamente toda concentrada no cimento o que é interessante para se analisar defeitos apenas no cimento e que em 39,17 kHz e 507 us/m a energia está distribuída entre o cimento e a coluna de produção, sendo interessante para analisar defeitos que envolvam ambos. / [en] In oil wells, a good cementation is essential to guarantee the structural support of the casing and isolate the well from groundwater. The variations in the material properties and the presence of defects in the cement can lead to leaks and environmental damage. During the deactivation and abandonment of the well in P&A operations (Plug & Abandonment), it is necessary to evaluate the cement condition as well as investigate possible defects. Since 50 s, cement bond logging tools capable of analyzing the cement condition have been developed and improved. The most famous tools were Cement Bond Logging Tools (CBT), based on CBL (Cement Bond Logging) and VDL (Variable Density Logging) operation technique and the Cement Evaluation Tools (CET). However, these tools were designed to operate only in single-casing set, without the tubing. Remove the tubing is an expensive process, so a challenge in the industry that remains open is the creation of a tool capable of operating in wells with tubing in order to reduce process costs or in wells that have multiple casings. In recent years, many patents and scientific paper have been published on the same topic. This work analyzes the effectiveness of the use of guided ultrasonic waves in multilayer wells to detect defects present in the cement layer. To this end, a vast bibliographic search was first carried out in order to identify the most frequent types of existing defects, the principle of operation of the main commercial tools and the advances in research on this subject. The well studied was modelled from analytical equations of the elastic wave theory, aiming at the dispersion equations that govern the problem. An analytical-numerical code was developed capable of solving these equations and obtaining the dispersion curves. Furthermore, it was analyzed how the defects and their variations affect the dispersion curves, identifying the characteristic behaviours for each case. Subsequently, the energy distribution, obtained by the Poynting vector, in the well was used in order to investigate the modes that concentrate the energy in the cement layer. For the single-casing, it was concluded that the best excitation modes were those with high frequency, because the energy is concentrated in cement. For through-tubing case, it was found that at a frequency of 30.13 kHz and a slowness of 726.5 us/m, the energy is virtually completely concentrated in cement, which is interesting to analyze defects present only in cement layer and that at 39.17 kHz and 507 us/m the energy is distributed between cement and tubing, being interesting to analyze defects that involve both layers.

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The identification and quantification of atoms, molecules, or ions concentrations in gaseous samples are in great demand for medical, environmental, industrial, law enforcement and national security applications. These applications require in situ, high-resolution, non-destructive, sensitive, miniature, inexpensive, rapid detection, remotely accessed, real time and continuously operating chemical sensing devices. The aim of this work is to design a miniature optical sensing device that is capable of detecting and measuring chemical species, compatible with being integrated into a large variety of monitoring systems, and durable enough to be used under extreme conditions. The miniature optical sensor has been realized by employing technologies from the optical communication industry and spectroscopic methods and techniques. Fused silica capillary tubing along with standard communication optical fibers have been utilized to make miniature gas sensor based on near-infrared spectroscopy for acetylene gas detection. In this work, the basic principles of infrared spectroscopy are reviewed. Also, the principle of operation, fabrication, testing, and analysis of the proposed sensor are discussed in details. / Master of Science

Made available in DSpace on 2014-07-29T15:13:47Z (GMT). No. of bitstreams: 1 TESE Julia de Miranda Moraes.pdf: 2895250 bytes, checksum: e061f736f6922f781b2c671bf4f90f32 (MD5) Previous issue date: 2012-08-17 / The aim of this work was to evaluate the regeneration of equine ulnar nerves submitted to neurotomy, silicone tubing and cell therapy with bone marrow mononuclear cells fraction (MCF) or adipose derived mesenchymal stem cells (ADSC). Fifteen adult horses were divided into three groups with five animals each: control group (CG) with the use of saline solution, group with FCM deposition and group with ADSC deposition. The same surgical procedure was performed in all groups, using both nerves of each animal (right and left), establishing two moments of biopsy: on the 13th week on the right limb (CG1, MCF1 and ADSC1) and on the 26th week on the left limb (CG2, MCF2 and ADSC2). The MCF and ADSC were obtained respectively, from bone marrow and adipose tissue from each animal, both used as an authologous implant. After 13 and 26 weeks, biopsies were performed in all groups and immediately it was made some fragments slide imprints for viewing the nanocrystal fluorescent label. The fragments were fixed in 10% buffered formalin for histological analysis, with HE, luxol fast blue, Masson's trichrome, immunohistochemistry against the antibodies neurofilament (NF), S-100, FGF-2 and GDNF. Microscopically it was observed the presence of axonal growth, connective tissue, inflammatory infiltrate, Schwann cells, neural growth factors, myelin sheath and wallerian degeneration. For histologic analysis, it was established qualitative scores and for immunohistochemistry it was performed quantitative analysis with Image J program. It was observed wallerian degeneration reduction, better fascicular reorganization, new collagen increased, myelin sheath early formation, and NF antibody stronger staining in the experimental groups compared to CG. The ADSC group presented the best results than the other groups, showing ADSCs efficiency compared to MCF and CG for peripheral nerve regeneration. However, it was proved a longer time necessity to occur complete regeneration of peripheral nerve after injury. / Este trabalho teve por objetivo avaliar a regeneração do nervo ulnar de equinos, submetidos à neurotomia, tubulização com tubo de silicone e terapia celular com fração de células mononucleares da medula óssea (FCM) ou células-tronco mesenquimais do tecido adiposo (ADSC). Foram utilizados 15 equinos adultos alocados em três grupos, com cinco animais em cada: grupo controle (GC) com utilização de soro fisiológico; grupo com deposição de FCM; e grupo com deposição de ADSC. Foi realizado o mesmo procedimento cirúrgico em todos os grupos, utilizando-se os dois nervos de cada animal (direito e esquerdo), e estabelecido dois momentos de biopsia: na 13ª semana com biopsia no membro direiro (GC1, FCM1 e ADSC1) e na 26ª semana com biopsia no membro esquerdo (GC2, FCM2 e ADSC2). A FCM e a ADSC foram obtidas respectivamente, da medula óssea e tecido adiposo de cada aninal, ambos utilizados como implantes autólogos. Após 13 e 26 semanas, realizaram-se as biopsias de todos os grupos e imediatamente, faziam-se imprints dos fragmentos para visualização do marcador fluorescente nanocristal. Os fragmentos foram fixados em formol tamponado a 10%, para análise histológica, com as coloraçãoes de HE, luxol fast blue, tricrômio de Masson e imuno-histoquímica com os anticorpos neurofilamento (NF), S-100, FGF-2 e GDNF. Microscopicamente avaliou-se a presença de proliferação axonal, tecido conjuntivo, infiltrado inflamatório, células de Schwann, fatores de crescimento neurais, bainha de mielina, e degeneração walleriana. Para a análise histológica estabeleceram-se escores qualitativos e para a imuno-histoquímica realizou-se análise quantitativa com o programa Image J. Foi observada diminuição da degeneração walleriana, melhor reorganização fascicular, aumento do colágeno novo, início de formação de bainha de mielina, além de maior marcação do anticorpo NF nos grupos experimentais em relação ao GC. O grupo ADSC apresentou melhores resultados em relação aos demais, enfatizando a eficiência das ADSCs em relação à FCM e ao GC para a regeneração nervosa periférica. Porém, há a necessidade de um tempo maior para ocorrer completa regeneração do tecido nervoso periférico após lesão.