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Search Results: 1 - 10 of 47374 matches for " Onélia Aparecida Andreo dos Santos "
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Effect of water losses by evaporation and chemical reaction in an industrial slaker reactor
Andreola, Ricardo;Vieira, Osvaldo;Santos, Onélia Aparecida Andreo dos;Jorge, Luiz Mario de Matos;
Brazilian Archives of Biology and Technology , 2007, DOI: 10.1590/S1516-89132007000200019
Abstract: a dynamic model of the slaker reactor was developed and validated for klabin paraná papéis causticizing system, responsable for white liquor generation used by the plant. the model considered water losses by evaporation and chemical reaction. the model showed a good agreement with the industrial plant measures of active alkali, total titratable alkali and temperature, without the need of adjustment of any parameter. the simulated results showed that the water consumption by the slaking reaction and evaporation exerted significant influence on the volumetric flow rate of limed liquor, which imposed a decrease of 4.6% in the amount of water in reactor outlet.
Modeling, simulation, and analysis of a reactor system for the generation of white liquor of a pulp and paper industry
Andreola, Ricardo;Jorge, Regina Maria Matos;Santos, Onélia Aparecida Andreo dos;Jorge, Luiz Mario de Matos;
Brazilian Archives of Biology and Technology , 2011, DOI: 10.1590/S1516-89132011000100024
Abstract: an industrial system for the production of white liquor of a pulp and paper industry, klabin paraná papéis, formed by ten reactors was modeled, simulated, and analyzed. the developed model considered possible water losses by the evaporation and reaction, in addition to variations in the volumetric flow of lime mud across the reactors due to the composition variations. the model predictions agreed well with the process measurements at the plant and the results showed that the slaking reaction was nearly complete at the third causticizing reactor, while causticizing ends by the seventh reactor. water loss due to slaking reaction and evaporation occurred more pronouncedly in the slaker reactor than in the final causticizing reactors; nevertheless, the lime mud flow remained nearly constant across the reactors.
Equa o de difus o n o linear, solu es e difus o an mala = Nonlinear diffusion equation, solutions and anomalous diffusion
Renata Ferreira Colli Badini,Giane Gon?alves,Marcelo Kaminski Lenzi,Onélia Aparecida Andreo dos Santos
Acta Scientiarum : Technology , 2007,
Abstract: Neste trabalho, investigaremos uma equa o de difus o n o linearconsiderando a presen a de termos convectivos, absorventes e um coeficiente de difus o dependente do tempo. Os termos n o lineares presentes na equa o ser o uma conseqüência do emprego de uma generaliza o n o linear da Lei de Darcy ( (r, t) = - (t)r-q r(r, t) r [r(r, t)]u ) n J D r ou da presen a de um termo absorvente n o linear (- a(t)[r(r, t)]m ) que pode, por exemplo, representar um processo de difus o com rea o. Em particular, para esta equa o de difus o obteremos uma nova classe de solu es e analisaremos os efeitos produzidos por tais termos, assim como rela o com processosdifusivos an malos. This work aimed to investigate a nonlinear diffusion equation by considering the presence of a time dependent diffusion coefficient, convective and absorbent terms. The nonlinear terms present in the diffusion equation are consequence of employing a nonlineargeneralization of Darcy’s law ( [ ] ) = - -q r r ) u (r, t) (t)r (r, t) r (r, t n J D r or a nonlinear absorbent term(- a(t)[r(r, t)]m ), which may be related to a reaction diffusion process. Particularly, we will obtain new classes of solutions, analyze the effects produced by these terms and the relation of the results presented here with anomalous diffusion.
Modelagem de um reator integral aplicado na rea o de reforma a vapor de metano = Modeling of integral reactor applied methane steam reforming
Giane Gon?alves,Daniel Russo,Ervin Kaminski Lenzi,Onélia Aparecida Andreo dos Santos
Acta Scientiarum : Technology , 2007,
Abstract: Freqüentemente, a valida o de modelos matemáticos aplicados a reatores industriais esbarra na dificuldade de obten o de medidas experimentais confiáveis. Uma maneira de contornar esta limita o corresponde à implanta o de uma unidade em escala de bancada devidamente instrumentada, na qual s o obtidos dados experimentais emcondi es controladas. Neste contexto, foram efetuados ensaios em um reator integral de reforma a vapor de metano em escala de bancada, em diversas condi es experimentais. As medidas de temperatura no leito foram efetuadas por meio de um termopar multiponto em seis posi es axiais distintas, enquanto a composi o do efluente do reator foi determinada por cromatografia gasosa. Estes dados experimentais foram comparados com as previs es de um modelo pseudo-homogêneo, unidimensional e dinamico. Os resultados indicam que o modelo é adequado, sendo que tanto a atividade catalítica como a convers o s o sensíveis à temperatura operacional, enquanto a temperatura do leito é praticamente insensível à vaz o nas condi es experimentais exploradas. Frequently, the validation of applied mathematical models of industrial reactors dash into the difficulty of obtaining reliable experimental data. A way to overcome this limitation is the proper use and operation or a in bench scale, experimental setup from whichexperimental data can be obtained in controlled conditions. In this context, experiments were carried out in an integral reactor of steam reform, in different experimental conditions. Thermocouples were placed along the catalyst bed to allow for temperature monitoring in six equally spaced and distinct positions of the reactor, the composition of the effluent of the reactor was determined by gas chromatography. These experimental data were compared with the theoretical results of a pseudo-homogeneous one-dimensional,dynamic mathematical model. The results indicate that the model can successfully describe the experimental data set and the catalytic activity and the conversion are sensitive to variations of the operational temperature, while the temperature of the bed is practically constant to the flow variations in the explored experimental conditions.
Simula o e análise de um sistema industrial de colunas de destila o de etanol = Simulation and analysis of an industrial system of columns for ethanol distillation
Maria Fatima Marquini,Douglas Castilho Mariani,Antonio José de Almeida Meirelles,Onélia Aparecida Andreo dos Santos
Acta Scientiarum : Technology , 2007,
Abstract: Um sistema industrial de colunas de destila o típico é composto por três colunas distintas e voltado à produ o de álcool etílico hidratado. Com o intuito de alcan ar uma melhor compreens o sobre o comportamento desse sistema, foram instalados diversos pontos de amostragem de temperatura, concentra o alcoólica, press o e vaz o ao longo da instala o. Essas medidas viabilizaram a avalia o da qualidade das previs es de um simulador de processos usual. A partir das simula es foi possível constatar que, dentre as equa es disponíveis no simulador para estimar os coeficientes de atividade, a equa o NRTL foi a que conduziu aos melhores resultados com os dados experimentais, com desvios em torno de 2 e 2,5% em rela o às temperaturas e concentra es alcoólicas, respectivamente, as quais foram medidas em várias bandejas das colunas de destila o quecomp e o sistema. A typical industrial system of distillation columns involves threecolumns for hydrated ethyl alcohol production. In order to obtain a better understanding of the behavior of this system, several sample points were installed along the distillation unit for measuring temperature, pressure and flow values, and also for collecting liquid phase samples in order to determine the corresponding alcoholic concentrations. The distillation unit involves three rectification and stripping columns. The experimental measurements made possible the evaluation of the quality of the process simulation results. The simulation results indicate that, among the equations available in process simulation for calculating the activity coefficients, the NRTL model was the one that leads to the best agreement with theexperimental data, with deviations around 2 and 2.5% in relation to temperatures and alcohol concentrations respectively, whose values were measured in several trays of the distillation unit.
Impregna o de filmes do compósito de policarbonato (PC) e sílicagel (Si) com corante fotocr mico em fluido supercrítico = Impregnation of composite from polycarbonate (PC) and silica gel (Si) films with photochromic dye in supercritical fluid
Fernanda de Almeida Fin de Lima,Onélia Aparecida Andreo dos Santos,Nanci Pinheiro
Acta Scientiarum : Technology , 2010,
Abstract: O objetivo deste trabalho foi estudar a impregna o do corante fotocromático Reversacol Graphit em filmes do compósito de policarbonato (PC) e sílica-gel (Si), com a finalidade de obter aplica es em lentes fotocr micas. Filmes de PC puros também foramimpregnados nas mesmas condi es, para verificar o efeito da adi o de sílica-gel. Os filmes do compósito foram produzidos em propor es de Si:PC de 1:40 e 1:80 (m m-1), pelo método casting. Para a impregna o do corante Reversacol Graphit nos filmes obtidos foiutilizado o processo supercrítico, pela sua eficiência e benefícios. A impregna o foi feita nos tempos de 15, 30, 45, 60, 90, 120, 150 e 180 min. A temperatura e a press o adotadas foram de 60oC e 120 bar. A quantidade de pigmento impregnado nos filmes de Si:PC – 1:40e 1:80 (m m-1) foi de 29 e 23% de massa de corante por massa de compósito, respectivamente, e para o filme de PC puro foi de apenas 2,2% massa de corante por massa de compósito. Pelas análises térmicas, verificou-se que os filmes do compósito apresentarammaior estabilidade térmica. Pela técnica de microscopia eletr nica, observou-se que os filmes de PC puro e dos compósitos Si:PC – 1:40 e 1:80 (m m-1) apresentaram uma superfície lisa e homogênea. The aim of this work was to study the impregnation of the photochromic dye Reversacol Graphit in composite films ofpolycarbonate (PC) and silica gel, with the purpose of finding applications in photochromic lenses. Pure PC films were also impregnated in the same conditions, to verify the effect of the silica-gel addition. The composites films were produced in Si:PC ratios of 1:40 and 1:80 (m m-1), using the casting method . For the impregnation of the dye Reversacol Graphit in the obtained films, the supercritical process was used due to its efficiency and benefits. The impregnation was made in the times of 15, 30, 45, 60, 90, 120, 150 and 180 minutes. The adopted temperature and pressure were 60oC and 120 bar, respectively. The amount of pigment impregnated in Si:PC films – 1:40 and 1:80 (m m-1) was 29 and 23% of dye mass per composite mass, respectively, and for pure PC film it was only 2.2% dye mass per composite mass. From the thermal analyses, it was verified that the composite films presented greater thermal stability. From the technique of electronic microscopy, it wasobserved that pure PC films and the composites Si:PC – 1:40 and 1:80 (m m-1) presented a smooth and homogeneous surface.
Desempenho de um reator integral de reforma a vapor de metano recheado com um catalisador industrial = Performance of an integral methane reforming fixed bed reactor packed with an industrial catalyst
Douglas Rodrigues Francisquini,Giane Gon?alves,Onélia Aparecida Andreo dos Santos,Luiz Mario de Matos Jorge
Acta Scientiarum : Technology , 2005,
Abstract: O presente trabalho tem por objetivo avaliar a atividade catalítica e o perfil de temperaturas num reator integral de reforma a vapor de metano, aquecido por forno elétrico e recheado com um catalisador industrial. Foram efetuadas medidas de temperatura no leito em nove posi es axiais distintas e a composi o dos produtos da rea o foram determinadas por cromatografia. Os ensaios foram conduzidos com o forno a 500, 600 e 700oC, raz o molar de alimenta o [H2O/CH4 ] = 4 e densidade fluxo-mássico de 0,2 e 0,5 kg/m2.s. Os resultados indicam que a utiliza o dos nove pontos foi suficiente para representar o comportamento térmico do reator e evidenciam a existência de perdas decalor significativas nas extremidades do reator. Tanto a atividade catalítica como a convers o apresentam-se sensíveis à temperatura operacional, entretanto, a temperatura do leito é praticamente insensível à vaz o nas condi es experimentais exploradas. The present work has the objective to evaluate the catalytic activity and the temperature profile inside an integral steam reforming fixed bed reactor heated by an electrical furnace and packed with an industrial catalyst. Nine temperature measures were made along nine axial positions and the composition of the products reaction were evaluated by gas chromatography. The experimental conditions were: temperatures furnace of 500oC, 600oC, and 700oC, feed molar ratio [H2O/CH4] = 4, and mass flow rate of 0.2 and 0.5 kg/m2.s. The results show that the use of the nine points was enough to represent the thermal behavior of the reactor. Both the catalytic activity and the conversion depend of operational temperature. However, the fixed bedtemperature is independent of mass flow rate at the used experimental conditions.
Titania comercial na descolora o fotocatalítica de corante proveniente da indústria têxtil = Commercial titania in photocatalytic discoloration of textile industry dye residues
Leda Maria Saragiotto Colpini,Helton José Alves,Onélia Aparecida Andreo dos Santos,Creusa Maieru Macedo Costa
Acta Scientiarum : Technology , 2006,
Abstract: Os efluentes têxteis caracterizam-se por serem altamente coloridos, fato que se deve à presen a de corantes que n o se fixam nas fibras durante o processo de tingimento, causando assim, grandes problemas ambientais. Um processo alternativo para eliminar a contamina o do meio ambiente por corantes é a oxida o desses materiais por meio dafotocatálise, na presen a de óxidos semicondutores como o TiO2. Neste sentido, TiO2 comercial foi utilizado como catalisador nos estudos fotocatalíticos de descolora o de solu es aquosas do corante têxtil C.I. reativo laranja-122. As rea es fotocatalíticas foram realizadas em um reator de vidro termostatizado e irradiado com uma lampada de 15 W. Observou-se 100% de descolora o das solu es em 120 minutos de rea o. Esses resultados indicam a eficiência do método de fotocatálise na descolora o do corante estudado. Textile effluents characteristically contain colored compoundsresulting from dyes unfixed to fibers during the dyeing process that cause serious environmental problems. An alternative process to prevent environmental contamination by these dyes is to oxidize them through photocatalysis in the presence of semiconducting oxides such as TiO2. In this sense, commercial TiO2 has been used as a catalyst in the photocatalytic study of discoloration of textile dye C.I. reactive orange-122 aqueous solutions. The photocatalytic reactions were carried in a thermostatized glass reactor and irradiated with a 15-W lamp. It was attained 100% dye discoloration in 120 min of reaction. This result indicates the efficiency of the TiO2 photocatalysis method in the discoloration of the studied dye.
Permanent Rare-Earth Magnets—The Need to Protect Them against Corrosion  [PDF]
lia Aparecida Lino dos Santos, Zehbour Panossian
Materials Sciences and Applications (MSA) , 2019, DOI: 10.4236/msa.2019.104024
Abstract: The RE-Fe-B permanent magnets have a complex microstructure and they are susceptible to corrosion process. In this paper, the commercial nickel coatings adhesion was investigated. The microstructure of the RE-Fe-B without coating was analyzed by scanning electronic microscopy and electrochemical techniques. The interface magnet/coating was studied by scanning electron microscopy and the nickel-plated Nd-Fe-B commercial magnets were tested in a salt spray chamber. The ferromagnetic and RE-rich phases were observed. After the anodic polarization curve, a strong intergranular corrosion was observed and the RE-rich phase was preferentially attacked. The interface magnet/Ni coating presented inter-granular corrosion that can affect the nickel coating adherence. This attack had probably occurred during the electrodeposition process. Not all the samples suffered localized corrosion during the salt spray tests and the Ni triple-layer coating presented a few corrosion points. RE-Fe-B alloy magnets need to be protected with appropriate coatings to each environment to which they will be exposed and the protective coating must not be damaged.
Agriculture and Forest Transition: Understanding of Land Use Change in a Cultural Landscape  [PDF]
José Eduardo dos Santos, Angela Terumi Fushita, Imyra Maíra Martins de Souza, Lia Martucci Amorim, Valéria Aparecida David Andrade
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.512076
Abstract: Land use trajectory analysis provides both the time and kind of land cover changes to monitor land use dynamics. Land cover change trajectories for three different dates (1965, 1989 and 2014) extracted from satellite images by vectorization of the thematic information were studied This study was carried out on a cultural landscape (S?o Carlos municipality, SP, Brazil) with three major land use-cover classes (forest, agriculture and other uses). The results showed the spatio temporal variability of landscape pattern and forest and agriculture change trajectories. Analysis based on these landscape trajectories demonstrates that agriculture and forest cover changes have been caused by human activities. The results reflect the conflicting interactions between environmental and human systems in the study area. A key question is that the pressure exerted on forest land use-cover depends on the incentives that move society from a conflicting relation with a municipal territory. A more sustainable landscape transition and trajectory for S?o Carlos municipality are extremely dependent on the regulatory role of the government through strategies related to the implementation of specific categories of legally protected areas (Legal Reserves and Areas of Permanent Preservation).
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