Thesis (Ph. D.)--Institute of Paper Chemistry, DATE. / Includes bibliographical references (p. 106-111).

The health of the transmission power transformers in the power system networks is critical to the reliability of electricity supply. Knowing the precise life expectancy of the transmission power transformer is of vital importance as it permits an optimised asset replacement. The traditionally regarded transmission power transformer’s life expectancy of 40 years is considered dated for the transformers in the UK according to the transformer life data in 2010. In this thesis, it is aimed to investigate the life expectancy of the transmission power transformer in the UK from three aspects: statistical analysis on historic transformer life data, thermal modelling of in-service transformers, and through the in-service transformers’ furan measurements.A detailed statistical analysis shows that deriving the transformer’s reliability at a certain age by calculating the hazard rate is inadequate, as the hazard rate at each age has a statistical range in which the confidence band width is related to the amount of the reliability data. The transformer life data in all ages are grouped together to derive a general hazard rate of 0.27%. It is concluded that the transformer life expectancy could not be derived via statistical approaches due to the limited data available at the older transformer ages.As an alternative approach, regarding the life of insulating paper as the ultimate life of a transformer, the thermal model published by the IEC transformer loading guide 60076-7 is reviewed and extended to estimate a transformer’s thermal lifetime. The model is improved in two aspects, such that Arrhenius equation is adopted to consider the paper’s practical ageing mechanism of oxidation and hydrolysis when calculating the paper’s ageing rate; and the model takes consideration of the paper’s moisture accumulation effect.The developed thermal model is used to reversely derive the generally unknown model input – hot-spot factor, by the means of regarding the scrapped transformer’s degree of polymerisation (DP) predicted thermal lives as a benchmark. Assigning the derived hot-spot factor to the field units with regard to the design family, the thermal lives of 106 in-service transformers have been estimated. To enlarge the life sample, the modelling lives are combined with the 79 scrapped transformers’ DP predicted thermal lives. The thermal life expectancy, defined as the median life of the sample set, is derived as 88 years. A series of sensitivity studies are performed to examine the derived life expectancy’s responses on the variations of load, winding-to-oil gradient, top-oil temperature rise, and the setting of winding temperature indicator.As a non-intrusive approach in transformer’s insulating paper assessment, the correlations between the 2-furaldehyde (2FAL) concentration dissolved in transformer oil and paper’s DP derived by different laboratories are reviewed which are found to differ significantly. As a first-time attempt to derive the 2FAL-DP correlation relationship for the field transformers, the paper’s DP is estimated at the age when oil was sampled using the thermal model, and is plotted with the 2FAL measurement. De Pablo’s equation is found to fit the plot of the DP estimates against the 2FAL measurements better than other function formats. The 2FAL concentrations corresponding to the paper’s critical DP levels are given using the developed 2FAL-DP correlation relationship.

This study combined photocatalytic technology with activated carbon cellulose-paper filter (ACCF) adsorption to decompose gaseous pollutants. Gaseous pollutants were initially adsorbed by activated carbon and could be further decomposed by photocatalytic technology. This study selected acetone (CH3COCH3) as gaseous pollutants. Two market available photocatalysts (photocatalysts¢¹and¢º) were coated on ACCF by impregnation to decompose acetone in a batch photocatlytic reactor. Operating parameters investigated in this study included initial acetone concentration (4.1~10.2 £gM), reaction temperature (40~70¢J), and water vapor (0~20 %). The incident UV light of 365 nm was irradiated by a 20-watt low-pressure mercury lamp placing above the batch photocatalytic reactor. The ACCF coated with TiO2 was placed at the center of the photocatalytic reactor. Acetone was injected into the reactor by a gasket syringe to conduct the photocatalytic tests. Reactants and products were analyzed quantitatively by a gas chromatography with an electron capture detector (GC/DCD) and a flame ionization detector followed by a methaneizer (GC/FID-Methaneizer). Finally, a Langmiur-Hinshewood (L-H) kinetic model was proposed to describe the rate of photocatalytic reaction. Results obtained from the photocatalytic tests indicated that photocatalyst¢º was better than photocatalyst¢¹ for the decomposition of acetone. Experimental results indicated that the size range of self-produced TiO2 photocatalyst by sol-gel was 20~70 nm. The end products were mainly CO and CO2, which resulted in the mineralization ratio up to 98%. Results obtained from the operating parameter tests revealed that the increase of initial acetone concentration enhanced the amount of acetone adsorbed on ACCF, which however did not increase the reaction rate of acetone. Although the increase of reaction temperature could reduce the amount of acetone adsorbed on ACCF, the decomposition rate of acetone could be promoted, so as the yield rate and mineralization ratio of products (CO and CO2). The increase of water vapor could slightly decrease the amount of acetone adsorbed on ACCF. The competitive adsorption phenomenon between acetone and water molecules on active sites could decelerate the decomposion of acetone. Moreover, the ACCF would not be saturated since the adsorbed acetone could be further decomposed quickly by the photocatalysts, which made the TiO2/ACCF more effective on removing acetone and lasted longer than the conventional ACCF. Finally, a modified bimolecular Langmuir-Hinshelwood kinetic model was developed to investigate the influences of initial acetone concentration reaction, temperature, and relative humidity on the promotion and inhibition for the photocatalytic oxidation of acetone. The modified L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone. Thus, the reaction rate of acetone over TiO2/ACCF could be described by the modified L-H kinetic model.

Made available in DSpace on 2015-03-26T13:28:34Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3222494 bytes, checksum: 78618fcec354fb9b93e356bb7523df94 (MD5) Previous issue date: 2014-01-20 / In the pulp and paper industry there is a large consumption of water in their processes which are directly linked to the issue of wastewater and characteristics of these effluents . Normally these industries treat their effluents by biological processes such as activated sludge and aerated lagoons . The treatment system aerated lagoons are classified as optional or complete mixing due to the power density of the aeration equipment . This study analyzes the performance of a complete-mix aerated lagoon followed by decantation pond of Santher paper mill located in Governador Valadares, Minas Gerais. Checks the current status of the treatment system with respect to flow, hydraulic detention time (HDT), power density, temperature and the availability of dissolved oxygen (DO) provided by nine aerators. The volumetric flow measurement method was used to determine a rate of 2419 m3/day, with corresponding and TDH's of 8.76 and 1.87 for the aeration and settling ponds, respectively. The temperatures did not exhibit large variations within each pond, the aerators indicated power density of 3.12 W/m3, a value close to the recommended minimum degree, and DO concentrations on the surface of the pond aeration above the recommended minimum, yet close the bottom of the pond, DO levels were observed in the range of 0 to 2.0 mg/L.. Physico-chemical characterization of the effluent was performed and compared to standards for effluent discharge in force in the State of Minas Gerais. Removal efficiencies of COD, BOD, TSS and oil and grease were 82%, 83%, 95% and 84%, respectively. Nitrogen and phosphorus were found in excess in the lagoons. The final effluent did not present acute toxicity to Daphnia similis or chronic toxicity to Ceriodaphnia dubia. The soluble COD removal coefficent for the complete mix aerated lagoon was estimated to be 0,23/day. Specific ultraviolet absorbance ( SUVA 254 ) of the effluent decreased at each stage of treatment, while UV 254 /UV 280 values remained constant throughout the system. The study also examined the occurrence of browning and odor generation in the settling pond, where the episodes were associated with lack of oxygen in the pond triggering anaerobic condition. / Na indústria de papel há grande consumo de água em seus processos, o que gera grande emissão de águas residuárias com diferentes características. Normalmente, essas indústrias tratam seus efluentes por processos biológicos como lodos ativados e lagoas aeradas. Os sistemas de tratamento por lagoas aeradas são classificados como aeradas facultativas ou de mistura completa, em função da densidade de potência dos equipamentos de aeração. O presente estudo analisa o desempenho de uma lagoa aerada de mistura completa seguida de lagoa de decantação da fábrica de papel SANTHER, situada em Governador Valadares-MG . Verificou-se a atual situação do sistema de tratamento com relação à vazão, tempo de detenção hidráulica, densidade de potência, temperaturas e disponibilidade de oxigênio dissolvido, fornecido por 9 aeradores. Utilizando-se o método volumétrico de medição de vazão foi medida uma vazão de 2419 m3/dia, e os TDH ́s de 8,76 e 1,87 dias para as lagoas de aeração e decantação, respectivamente. As temperaturas não apresentaram grandes variações no interior de cada lagoa, os aeradores indicaram densidade de potência de 3,12 W/m3, valor próximo ao mínino recomendado, e OD com concentrações na superfície da lagoa de aeração superiores ao mínimo recomendado, porém, próximo ao fundo da lagoa, foram constatados teores de OD na faixa de 0 a 2,0 mg/L. Foi realizada uma caracterização físico-química do efluente e comparado aos padrões de lançamento de efluentes vigentes nos Estado de Minas Gerais. As eficiências de remoção de DQO, DBO, SST e óleos e graxas foram de 82%, 83%, 95% e 84%, respectivamente. Nitrogênio e fósforo apresentaram-se em excesso no efluente da lagoa aerada. O efluente final não apresentou toxicidade aguda à Daphnia similis e nem toxicidade crônica à Ceriodaphnia dúbia. O valor do coeficiente da DQO solúvel estimado para a lagoa aerada de mistura completa foi de 0,23/d. A absorvância ultravioleta específica (SUVA254) aumentou ao longo do sistema de tratamento, enquanto os valores de UV254/UV280 permaneceram constantes. O estudo também analisou a ocorrência de escurecimento e geração de odor na lagoa de decantação, em que os episódios foram associados a falta de oxigênio na lagoa desencadeando a condição de anaerobiose.

Os materiais absorvedores de radiação eletromagnética (MARE) têm recebido muita atenção nas últimas quatro décadas, devido à crescente utilização para atender as exigências das legislações governamentais no controle de níveis de radiação eletromagnética espúria emitida por equipamentos eletrônicos, das normas industriais de compatibilidade e interferência eletromagnética, envolvendo basicamente as indústrias de equipamentos eletrônicos e telecomunicações, bem como a demanda da sociedade na confiabilidade nos equipamentos eletrônicos. O presente trabalho tem como objetivo estudar a produção e a caracterização de MARE na faixa de freqüências compreendida entre 8,2 12,4 GHz, baseados em papel celulósico impregnado com negro de fumo e matriz tipo poliuretano, aplicado por meio de pistola de pintura. Seis diferentes condições de impregnação foram estudadas, variando distância de aplicação e número de demãos (uma em cada lado do papel celulósico): 25 cm 2 demãos, 25 cm 4 demãos, 30 cm 2 demãos, 30 cm 4 demãos, 40 cm -2 demãos e 40 cm 4 demãos. Os resultados médios obtidos da caracterização eletromagnética dos seis lotes, via medição dos parâmetros S (S11/S22 Energia refletida, Er e S12/S21 Energia transmitida, Et) e calculo da energia absorvida (Ea), mostram que para os lotes com duas demãos, quanto maior a distância de aplicação, menores são os valores de Er e Ea e maior é a Et, uma vez que a gramatura do MARE diminui. Para os lotes com quatro demãos, quanto maior a distância de aplicação, menor é a Er e maior a Et. Entretanto, o parâmetro Ea para o lote com quatro demãos não se comporta como o lote com duas demãos, pois entre as distâncias de aplicação 25 cm e 30 cm é observada a queda de Ea, mas com a distância de aplicação 40 cm o valor de Ea aumenta, pois a onda eletromagnética consegue penetrar mais efetivamente no material, ou seja, há uma determinada concentração de centros absorvedores no substrato que permite maior interação do material com a onda eletromagnética. A partir dos valores de Ea, Er e Et foram selecionados 3 condições de impregnação para montagem de um MARE baseado em 8 tubos de celulose montados lado a lado formando um quadrado, sendo cada tubo com dimensões de 50 cm de comprimento e diâmetro de 7,6 cm, dobrados ao meio para promover múltiplas reflexões do sinal e assim aumentar a atenuação do sinal. As condições de impregnação foram escolhidas a partir da análise dos resultados dos seis lotes com base no menor valor de energia refletida e maior energia absorvida, na seguinte ordem crescente: 25 cm 4 demãos, 25 cm 2 demãos e 40 cm 2 demãos. Os resultados de refletividade no arco NRL mostram que a maior atenuação é obtida no lote com menor valor de energia refletida (40 cm 2 demãos, -8,20 dB/84,8% em média) e a menor atenuação no lote com maior valor de energia refletida (-2,84 dB/48,0%). Estes resultados demonstram que para um MARE baseado em múltiplas reflexões possuir alta eficiência de absorção de energia, o mesmo deve possuir baixos valores de energia refletida, pois a onda eletromagnética deve ter capacidade de penetrar na estrutura do material, fazendo com que a reflexão seja diminuída. / The electromagnetic absorbers has been receiving a lot of attention in the last four decades, due to their growing use in order to attend the demands of governmental control laws of electromagnetic radiation spurious levels emitted by electronic devices, industrial standards of electromagnetic compatibility (EMC) and electromagnetic interference (EMI), basically involving electronic and telecommunication industries, as well the demand of the society on the reliability of electronic equipments. The aim of the present work is to study the production and characterization of electromagnetic absorbers in the frequency range of 8,2 12,4 GHz, based on cellulose paper impregnated with carbon black and poliuretanic matrix, applied with spray gun. Six different conditions of impregnation were studied by varying the application distance and number of coats (one coat on each paper side): 25 cm 2 coats, 25 cm 2 coats, 25 cm 4 coats, 30 cm 2 coats, 30 cm 4 coats, 40 cm - coats and 40 cm 4 coats. The results of scattering parameters (S11/S22 reflected energy, Er and S12/S21 transmitted energy, Et) and calculated absorbed energy (Ea) for the six conditions showed that the conditions with two coats, the larger coat application distance, the smaller are the values of Er and Ea and the larger is Et, due to the decrease of paper gramature. The conditions with four coats, the larger coat application distance, the smaller is the value of Er and larger is the Et. However, the values of Ea for the condition with four coats has different behavior when compared with the condition with two coats, because between application distances of 25 cm and 30 cm is observed the decrease of Ea values, but with the application distance of 40 cm the Ea value increases, because the electromagnetic wave can penetrate more effectively in the material bulk, or be, there is a concentration of absorbers centers inside the material that allows a stronger interaction with the electromagnetic wave. Based on the values of Ea, Er and Et for the six conditions, were selected three conditions to assemble an electromagnetic absorber based on eight cellulose tubes, places side by side in order to form a square, with each tube with dimensions of 50 cm length and 7,6 cm diameter, bended in the middle portion to promote multiple reflections of electromagnetic wave in order to increase the signal attenuation. The conditions of tubes impregnation were chosen by the analysis of the six conditions results, based on the smaller value of Er and the larger value of Ea: 25 cm 4 coats, 25 cm 2 coats e 40 cm 2 coats. The reflectivity results of NRL arch shows that the larger attenuation is observed with the condition that present the smaller reflected energy (40 cm 2 coats, -8,20 dB/84,8%) and the smaller attenuation in the lot with the larger value of reflected energy (-2,84 dB/48,0%). These results shows that for an electromagnetic absorber based on multiple reflections possess high efficiency of energy absorption, the material must possess lower values of reflected energy, because the electromagnetic wave must have the capacity to penetrate in the bulk of the material, decreasing the reflection.

Cette thèse comporte un volet papetier et un volet textile. Dans le premier volet, de nouveaux produits capables d’améliorer la résistance à l’état humide (REH) du papier et qui soient si possible ‘écologiques’ ont été recherchés. Dans ce but, nous avons synthétisé avec de bons rendements des sels d’ammoniums quaternaires (SAQs) allylés dont beaucoup sont originaux. Ces sels ont été par la suite polymérisés à l‘aide d’un réacteur micro-onde. Les polymères obtenus sont cationiques, hydrosolubles et amphiphiles. Après fixation sur papier, nous avons mis en évidence qu’un traitement bicouche avec un copolymère amphiphile à base de bromure N,N-diallyl-pyrrolidinium (BDAP) et de carboxyméthylcellulose (CMC) apporte de façon inattendu un caractère hydrophobe marqué au papier traité alors que des copolymères réactifs synthétisés à base de N,N-diallyl-3-hydroxy-azétidinium (CDAHA) sont capables de conférer au papier une REH comparable à celle fournie par les résines polyamide-amine-épichlorhydrine (ou PAE) commerciales. Concernant le volet textile, l’objectif était de produire une recette optimale de traitement infroissable pour un tissu 100% coton à base d’acides polycarboxyliques, qui soit performante, non onéreuse et écologique. Pour cela, nous avons choisi l’acide citrique (AC) comme étant l’élément actif de la recette qui est à base de 5% d’AC et d’un mélange de catalyseurs : hypophosphite de sodium / cyanamide (1 éq ; 0,75 : 0,25). La température et le temps de réticulation ont été optimisés respectivement à 170°C et 90 s. L’infroissabilité ainsi conférée peut être estimée au mieux à assez bonne. En contrepartie, ce traitement infroissable engendre une dégradation de la résistance à la traction et du degré de blanc du support. Des supports de coton traités avec la recette optimale et éventuellement d’autres recettes ont été caractérisés par différentes méthodes analytiques. Les résultats trouvés montrent que la réaction d’estérification de la cellulose avec l’AC se produit principalement dans la paroi cellulaire et non pas en surface des fils de coton. En outre, le degré de polymérisation de la cellulose traité chute de 60%, ce qui est en accord avec les mesures dynamométriques déjà réalisées. / This work is divided into two parts: a papermaking part and a textile one. In the first part, new and if possible ‘green’ products, which can improve paper wet-strength, have been designed. For this purpose, unsaturated quaternary ammonium salts (SAQs), many of them unpublished so far, were synthesized. These salts were then polymerized using a microwave reactor. The resulting (co)polymers are cationic, water-soluble and amphiphilic. We demonstrated that papers, once treated by an amphiphilic N,N-diallyl-pyrrolidinium-based copolymer and carboxymethylcellulose (CMC) via a bi-layer treatment, were endowed with an obvious hydrophobic character. Moreover, other copolymers synthesized from N,N-diallyl-3-hydroxy-azetidinium (CDAHA) were able to impart to paper sheet a wet-strength comparable to that usually provided by polyamide-amine-epichlorohydrin (PAE) resins. The second part of the present work is dedicated to the development of an optimal anti-wrinkle recipe for cotton fabrics based on polycarboxylic acids. This recipe should be ideally efficient, cheap and eco-friendly. For that goal, citric acid (CA) was used as the active medium of the recipe that was based on 5% aq AC (w/w) solution and a catalyst mixture: sodium hypophosphite / cyanamide (1 eq, 0.75, 0.25). Temperature and heating duration was respectively optimized at 170°C and 90 s. Resulting crease-resistant properties can be estimated at best to good. However, such an anti-wrinkle treatment causes a degradation of both tensile strength and whiteness index. Cottons treated with the optimum recipe and other recipes were characterized by different analytical methods. Data showed that esterification reaction of cellulose with AC occurs mainly in the cell wall and does not affect the yarn surface. In addition, polymerization degree of treated cellulose was reduced of 60% in accordance with already measured mechanical properties.