Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-04-26T19:29:13Z No. of bitstreams: 1 DiogoRosemberghDaSilvaNobrega_DISSERT.pdf: 3407619 bytes, checksum: a00b7d07c5d402e8c57a1d3b73198713 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-28T23:50:33Z (GMT) No. of bitstreams: 1 DiogoRosemberghDaSilvaNobrega_DISSERT.pdf: 3407619 bytes, checksum: a00b7d07c5d402e8c57a1d3b73198713 (MD5) / Made available in DSpace on 2016-04-28T23:50:33Z (GMT). No. of bitstreams: 1 DiogoRosemberghDaSilvaNobrega_DISSERT.pdf: 3407619 bytes, checksum: a00b7d07c5d402e8c57a1d3b73198713 (MD5) Previous issue date: 2015-03-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Na ind?stria do petr?leo, a ?gua produzida ? o maior volume l?quido produzido com grande capacidade poluidora. Dentre os contaminantes org?nicos, os arom?ticos apresentam o principal risco ao meio ambiente e ? sa?de da popula??o principalmente BTEX. Ao longo dos ?ltimos anos, a eletroqu?mica tem se mostrado eficiente na degrada??o desses compostos, envolvendo apenas a utiliza??o de el?trons como reagentes. Entretanto, o desenho do reator eletroqu?mico, hidrodin?mica e, consequentemente, o coeficiente de transfer?ncia de massa s?o par?metros determinantes na efici?ncia do processo eletroqu?mico. Dentro desse contexto, o objetivo deste trabalho foi investigar geometrias de c?lulas eletroqu?micas, visando determinar os coeficientes de transfer?ncia de massa e entender a sua hidrodin?mica. Foram estudadas c?lulas em batelada e em fluxo, variando a pot?ncia da agita??o, posi??o da agita??o e espa?amento entre os eletrodos, empregando a t?cnica de corrente limite, com um gradiente de concentra??o de 4 a 24 mmol/dm? de K4[Fe(CN)]6 em propor??o molar de 2:1 para K3[Fe(CN)]6 em meio de NaOH 0,5 mol/dm?, a fim de determinar a corrente limite, e consequentemente o coeficiente de transfer?ncia de massa (km). Os resultados obtidos mostraram claramente que na c?lula em batelada, o aumento da agita??o e a posi??o da agita??o influenciaram o km; na c?lula em fluxo, o afastamento dos eletrodos n?o mostra influencia significativa quando a agita??o (fluxo) ? direcionada ? superf?cie do eletrodo; e ainda, as c?lulas em fluxo se mostraram mais eficientes no que diz respeito ? elimina??o de resist?ncias f?sicas inerentes ao tratamento eletro-oxidativo. Por fim, os resultados alcan?ados mostraram que ? poss?vel a aplica??o do reator eletroqu?mico no tratamento de BTX, uma vez que foi identificada uma geometria com o melhor coeficiente de massa, favorecendo a oxida??o das esp?cies na superf?cie do eletrodo, de forma mais r?pida e eficiente. / The oil and gas production processes generate large volumes of waste with high toxicity. In this industry, produced water is the most produced liquid volume with great polluting capacity. Among the organic contaminants, the aromatics, mainly BTEX, present a major risk to the environment and people's health. Over the past years, many studies have been conducted under the electrooxidation of aromatic compounds, showing that the electrochemical degradation is efficient for these substances, even more importantly, the process involves only the use of electrons as reactants. However, the design of the electrochemical reactor, hydrodynamics and mass transfer coefficients are critical parameters on the efficiency of the electrochemical process. In this context, the objective of this study was to investigate geometries of electrochemical cells, to determine the mass transfer coefficients and understand their hydrodynamics. Cells were studied in batch and flow design, varying stirring rate, the stirring position and spacing between electrodes. In order to determine the current limit, and thus the mass transfer coefficient (Km), it was used a concentration gradient of K4[FeCN]6 / K3[FeCN]6 (2:1) from 4 to 24 mM, in medium of 0.5 M NaOH. The results clearly showed that regarding the batch cell, increasing stirring rate and changing its position promote a considerable effect on Km; in the flow cell, no influences were achieved when the spacing of the electrodes was modified when the stirring (flow) is directed to the electrode surface; and, the flow cells are more efficient with regard to the elimination of inherent physical resistance to the electrochemical treatment. Finally, the results showed that the application of reactor is possible to treat electrochemically BTX because the better geometry has been identified, favoring the oxidation of the species on the electrode surface more rapidly and efficiently.

Made available in DSpace on 2014-12-17T15:01:56Z (GMT). No. of bitstreams: 1 LuizFSF_TESE.pdf: 2382677 bytes, checksum: 16f0fd92d4efa3b045a66f19b62ab2ea (MD5) Previous issue date: 2013-09-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Natural gas, although basically composed by light hydrocarbons, also presents contaminant gases in its composition, such as CO2 (carbon dioxide) and H2S (hydrogen sulfide). The H2S, which commonly occurs in oil and gas exploration and production activities, causes damages in oil and natural gas pipelines. Consequently, the removal of hydrogen sulfide gas will result in an important reduction in operating costs. Also, it is essential to consider the better quality of the oil to be processed in the refinery, thus resulting in benefits in economic, environmental and social areas. All this facts demonstrate the need for the development and improvement in hydrogen sulfide scavengers. Currently, the oil industry uses several processes for hydrogen sulfide removal from natural gas. However, these processes produce amine derivatives which can cause damage in distillation towers, can cause clogging of pipelines by formation of insoluble precipitates, and also produce residues with great environmental impact. Therefore, it is of great importance the obtaining of a stable system, in inorganic or organic reaction media, able to remove hydrogen sulfide without formation of by-products that can affect the quality and cost of natural gas processing, transport, and distribution steps. Seeking the study, evaluation and modeling of mass transfer and kinetics of hydrogen removal, in this study it was used an absorption column packed with Raschig rings, where the natural gas, with H2S as contaminant, passed through an aqueous solution of inorganic compounds as stagnant liquid, being this contaminant gas absorbed by the liquid phase. This absorption column was coupled with a H2S detection system, with interface with a computer. The data and the model equations were solved by the least squares method, modified by Levemberg-Marquardt. In this study, in addition to the water, it were used the following solutions: sodium hydroxide, potassium permanganate, ferric chloride, copper sulfate, zinc chloride, potassium chromate, and manganese sulfate, all at low concentrations (?10 ppm). These solutions were used looking for the evaluation of the interference between absorption physical and chemical parameters, or even to get a better mass transfer coefficient, as in mixing reactors and absorption columns operating in counterflow. In this context, the evaluation of H2S removal arises as a valuable procedure for the treatment of natural gas and destination of process by-products. The study of the obtained absorption curves makes possible to determine the mass transfer predominant stage in the involved processes, the mass transfer volumetric coefficients, and the equilibrium concentrations. It was also performed a kinetic study. The obtained results showed that the H2S removal kinetics is greater for NaOH. Considering that the study was performed at low concentrations of chemical reagents, it was possible to check the effect of secondary reactions in the other chemicals, especially in the case of KMnO4, which shows that your by-product, MnO2, acts in H2S absorption process. In addition, CuSO4 and FeCl3 also demonstrated to have good efficiency in H2S removal / O g?s natural, embora seja composto basicamente de hidrocarbonetos leves, apresenta tamb?m em sua composi??o gases contaminantes como o CO2 (Di?xido de carbono) e o H2S (Sulfeto de hidrog?nio). O H2S, que comumente ocorre nas atividades de explora??o e produ??o de ?leo e g?s, danifica as tubula??es de transporte do petr?leo e do pr?prio g?s natural. Por isso, a elimina??o do sulfeto de hidrog?nio levar? a significativa redu??o dos custos de opera??o e a uma melhor qualidade do ?leo destinado as refinarias, resultando assim num beneficio econ?mico, ambiental e social. Tudo isso demonstra a necessidade de desenvolvimento e aprimoramento de sequestrantes que removam o sulfeto de hidrog?nio da ind?stria de petr?leo. Atualmente existem v?rios processos para o tratamento do g?s natural, utilizados pela ind?stria petrol?fera para remo??o do H2S, no entanto, eles produzem derivados de aminas que danificam as torres de destila??o, formando precipitados insol?veis que provocam entupimento dos dutos e originam res?duos de grande impacto ambiental. Por isso, a obten??o de um sistema est?vel em meio reacional inorg?nico ou org?nico capaz de remover o sulfeto de hidrog?nio sem formar subprodutos que afetem a qualidade e o custo do processamento, transporte e distribui??o do g?s natural ? de grande import?ncia. Para estudar, avaliar e modelar a transfer?ncia de massa e a cin?tica da remo??o do sulfeto de hidrog?nio (H2S) montou-se uma coluna de absor??o contendo an?is de raschig, por onde o g?s natural contaminado com H2S atravessava uma solu??o aquosa de compostos inorg?nicos estagnada, sendo por esta absorvida. A essa coluna foi acoplado a um sistema de detec??o de H2S com interface com o computador. Os dados e Equa??es do modelo foram resolvidos pelo m?todo de m?nimos quadrados modificado de Levemberg-Marquardt. Neste estudo al?m da ?gua foram utilizadas as solu??es de hidr?xido de s?dio, permanganato de pot?ssio, sulfato de cobre, cloreto f?rrico, cloreto de zinco, cromato de pot?ssio, sulfato de mangan?s, a baixas concentra??es, na ordem de 10 ppm, com o objetivo ? avaliar a interfer?ncia entre par?metros f?sicos e qu?micos da absor??o, ou mesmo buscar um melhor coeficiente de transfer?ncia de massa como ? o caso dos reatores de mistura e colunas de absor??o operando em contra corrente. Nesse contexto a avalia??o da remo??o do H2S surge como um procedimento valioso para o tratamento do g?s natural e destino dos subprodutos do processo. Os estudos das curvas de absor??o obtidos permitiram determinar a etapa controladora da transfer?ncia de massa dos processos envolvidos, os coeficientes volum?tricos de transfer?ncia de massa e as concentra??es de equil?brio, assim como, efetuar um estudo cin?tico. Os resultados mostraram que a cin?tica de remo??o do H2S ? maior para o NaOH, mas como o estudo foi realizado em baixas concentra??es de reagente pode-se verificar o efeito das rea??es secund?rias nos outros reagentes, principalmente no caso do KMnO4, que mostra seu sub produto, MnO2, tamb?m atua na absor??o do H2S. O CuSO4 e o FeCl3 tamb?m apresentaram boa efici?ncia de remo??o

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-05T18:21:53Z No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) / Made available in DSpace on 2016-10-05T18:21:53Z (GMT). No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) Previous issue date: 2016-01-25 / Petrobras / The drilling of wells in salt layers faces major challenges in Brazil?s oil industry. Drilling in such layers requires the development of new technologies and operational procedures to make the process economically viable. One of the main problems is the dissolution of the salt layers in water-based drilling fluids. An uncontrolled dissolution presents a potential risk for the operation and can cause abrupt changes in the properties of the fluids. The main objective of this work was to study the effects of the dissolution of sodium chloride particles in non-Newtonian fluids containing xanthan gum. The study was divided into three parts, rheological experiments, kinetics experiments in a mixing tank and a mathematical modeling. The rheological experiments aimed at studies of the effect of the addition of saline particles on the rheology of non-Newtonian fluids, the effect of the concentration of suspended particles in the rheology of saturated fluids and the effect of the size of suspended particles in the rheology of saturated fluids. The Einstein equation was used to calculate the apparent viscosity of saturated fluids, taking into account the effect of the concentration of salt particles in suspension. The experiments in the mixing tank aimed at the study of the kinetics of dissolution with time in different operating conditions. Fluids were prepared using different concentrations of xanthan gum and different initial concentrations of sodium chloride. The effects of the viscosifier concentration and the initial concentration gradient were evaluated. A phenomenological model was used to represent the dissolution process, which provides the variation of the concentration of the fluid, the variation of the volume fraction of solids, the variation of the particles mean diameter and the variation of the interfacial mass transfer area as a function of time. In the rheology studies, it was verified that the addition of sodium chloride to the non-Newtonian fluid, in the studied conditions, increased the apparent viscosity of the solution. The increase of the concentration of suspended sodium chloride particles increased the apparent viscosity of the suspensions. The increase of the size of the suspended particles decreased the apparent viscosity of the suspension. Statistical tests were made in order to evaluate the statistical relevance of the performed studies. In the kinetics study, the convective mass transfer coefficient was estimated and simulations were made for the other variables of the process. The estimations showed that the xanthan gum concentration in the fluid and the initial sodium chloride concentration in the fluid affect the mass transfer coefficient. The average relative error observed for the simulations was 2,2%. / A perfura??o de po?os em camadas salinas enfrenta grandes desafios na ind?stria de petr?leo do Brasil. A perfura??o em tais camadas exige o desenvolvimento de novas tecnologias e procedimentos operacionais para tornar a perfura??o economicamente vi?vel. Um dos principais problemas enfrentados ? a dissolu??o das camadas de sais em fluidos de perfura??o base ?gua. Uma dissolu??o descontrolada apresenta um risco em potencial para a opera??o, podendo causar mudan?as bruscas nas propriedades dos fluidos. Este trabalho teve como principal objetivo estudar os efeitos da dissolu??o de part?culas de cloreto de s?dio em fluidos n?o-Newtonianos contendo goma xantana. O estudo foi dividido em tr?s partes, experimentos reol?gicos, experimentos de cin?tica em um tanque de mistura e modelagem matem?tica. Os experimentos reol?gicos tiveram como objetivo os estudos do efeito da adi??o de part?culas salinas na reologia de fluidos n?o-Newtonianos, do efeito da concentra??o de part?culas suspensas na reologia de fluidos saturados e do efeito do tamanho das part?culas suspensas na reologia de fluidos saturados. A equa??o de Einstein foi utilizada para calcular a viscosidade aparente dos fluidos saturados levando em conta o efeito da concentra??o de part?culas salinas em suspens?o. Os experimentos no tanque de mistura tiveram como objetivo o estudo da cin?tica de dissolu??o com o tempo em diferentes condi??es operacionais. Foram preparados fluidos com diferentes concentra??es de goma xantana e diferentes concentra??es iniciais de cloreto de s?dio. Foi analisado o efeito da concentra??o do viscosificante na cin?tica de dissolu??o bem como o efeito do gradiente de concentra??o inicial. Um modelo fenomenol?gico foi utilizado para representar o processo de dissolu??o, o qual prev? as varia??es da concentra??o do fluido, a varia??o da fra??o volum?trica de s?lidos, a varia??o do di?metro m?dio das part?culas e a varia??o da ?rea interfacial de transfer?ncia de massa em fun??o do tempo. Nos estudos de reologia, verificou-se que a adi??o de cloreto de s?dio ao fluido n?o-Newtoniano, nas condi??es estudadas, aumentou a viscosidade aparente da solu??o. O aumento da concentra??o de part?culas suspensas de cloreto de s?dio provocou um aumento na viscosidade aparente das suspens?es. O aumento do tamanho das part?culas suspensas de cloreto de s?dio diminuiu a viscosidade aparente da suspens?o. Testes estat?sticos foram feitos para analisar a relev?ncia estat?stica dos estudos realizados. No estudo da cin?tica, o coeficiente convectivo de transfer?ncia de massa foi estimado e simula??es foram feitas para as demais vari?veis do processo. As estima??es mostraram que a concentra??o de goma xantana no fluido e a concentra??o inicial de cloreto de s?dio no fluido influenciam o coeficiente de transfer?ncia de massa. O erro relativo m?dio simula??es observado para as simula??es foi de 2,2%.