RCAAP Repository

The detailed study of the screen operation considering cause and effect amongst several involved operational variables takes a prominent position regarding the solid-liquid separation. The general objective of this dissertation was the initial study of the vibrating screening that can be extended to the solid control in drilling rigs and the specific goal of this work was to assess the effects of screen aperture, volumetric concentration of solids in the feed and vibration (or g-force) upon the moisture of the retained material, the overall granulometric e fficiency of separation and the cut diameter by using a suspension of phosphatic rock and xanthan gum diluted in water. An experimental design 3k was created to execute the experiments, where the screen apertures were 95, 106 and 130 µm, volumetric concentration of solids in the feed 1, 2 and 3% and g-force of magnitude 1.00, 2.25 and 3.50. For the performance of the experiments, a pilot scale vibrating screen was used that processed 159 liters in 18 minutes. The results showed that the minimum moisture was obtained with the screen of 95 µm, volumetric concentration of 1% and vibration of magnitude 1.0 g, whereas for the overall granulometric efficiency the maximum condition was with 106 µm screen aperture, concentration of 1% and vibration of 1.0 g. The optimal point covering high efficiency and low moisture was achieved with 95 µm screen aperture, volumetric concentration between 2 and 3% and the least intense vibration(1.0 g). For the cut diameter the results obtained for each screen showed that its value decreased with the use of more intense vibration. The results obtained in the developed work are important to understand the main operational aspects in the solid-liquid separation by using shale shakers.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Recombinant proteins expressed in cell culture have been shown to be relevant in the biopharmaceutical production focusing human heaths. Insulin, interferon and vaccine against B hepatitis are products obtained from recombinant expression system. Importantly, the precipitation is a widely used technique for separating proteins from a mixture due to its simplicity, and the process is incremented by the use of salts. This study initially dealt with the validation of the salt precipitation method by using the purified BSA and trypsin, and then, to investigate the precipitation process of recAVLOEc protein synthesized by cells of E. coli BL21 (DE3) pLysS used as expression system for the AVLO. This protein has shown antiviral activity and it found in the hemolymph of Lonoimia obliqua caterpillar. The precipitation was conducted by the use of conventional salts (ammonium sulfate and sodium sulfate) and the volatile salt ammonium carbamate. The proteins of the bacterial expression system were evaluated for their antiviral potential virus-infected cell cultures. Bacterial cells were resuspended in phosphate buffer and lysade by ultrasound. In the experimental procedure, the saturated salt solution (ammonium sulfate, sodium sulfate or ammonium carbamate) was added dropwise to the protein solution. This mixture was kept at constant temperature of 5°C for 24 h. The supernatant phase was separated from the precipitate phase by centrifugation. The protein precipitate obtained from bacterial lysate was then added to cultures of L929 and Vero cells to evaluate the cytotoxic effect; and cultures of these cells were subsequently infected with virus (EMC and measles). The results showed better efficiency of sodium sulfate on the precipitation of BSA compared to ammonium sulfate, while for trypsin, the ammonium carbamate showed more effective. Toxic effect on the culture of L929 cells was observed for the precipitate obtained by the use of ammonium sulfate and sodium sulfate. However, as expected, the precipitated protein obtained by the use of volatile ammonium carbamate salt showed a lower cytotoxic effect. Tests in L929 cultures infected with EMC, were performed; however, protein samples obtained by conventional and volatile salts used as a precipitating agent did not show antiviral action. In Vero cell cultures, the precipitated protein from cell lysate by sodium sulfate showed antiviral action for measles.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The drilling process is one of the most costly and polluting phases in oil production. In that stage, large amounts of drilling fluid are used for removing the drilled cuttings of the well. This fluid requires constant treatment, in the form of solid removal, so it can be properly reused for injection. This treatment is usually performed by a system that involves the use of hydrocyclones, sieves, rotational dryers and decanter centrifuges. The centrifuges, mainly responsible for fine solids recovery, has its application limited by the high installation and maintenance costs involved and platform space restrictions, and thus not being able to process the entire volume of circulating fluid in the drilling system. Thereby, the present work propose the use of mini hydrocyclones ( 30 c D mm  ) in support of decanter centrifuges, aiming a higher fine cuttings removal of drilling fluid. To this end, an operational and geometric parameters effects study were performed, followed by optimization, in order to obtain a geometry with high efficiency and low liquid ratio. This geometry, referred as optimal geometry, was then tested on the operation with different fluids (water+ carboxymethylcellulose) having rheological characteristics (pseudoplastic fluid) similar to the one commonly used in drilling process. Finally, the obtained results were implemented in a simulation of the optimum hydrocyclone, using for that, a granulometric size distribution from a centrifuge drilled cuttings sample and also analyzing the serial operation of the equipment. The results obtained for the optimal geometry showed high levels of total efficiency (81-89%) while maintaining reasonable values of underflow-to-throughput ratios. In sequence, empirical expressions for the pseudoplastic fluid operation were obtained for total efficiency, underflow-to-throughput ratio, cut diameter and flowrate, with coefficients of determination above 0.986. Finally, simulation results of serial operation showed that the tested hydrocyclones may promote a reduction of up to 24% on the fluid solid content, while also allowing high flexibility during the different phases of drilling.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

In this work, nickel catalysts supported on CeO2/Al2O3 and CeZrO2/Al2O3 were investigated in reforming autothermal of methane, aiming hydrogen production. Two types of aluminas with different areas were used (Al2O3-D and Al2O3-C). Therefore, two catalysts series were prepared: one was supported on Al2O3-D, and another series supported on Al2O3-C. The characterization techniques used were BET surface area, X-Ray Diffraction (XRD), Temperature programmed reduction (TPR-H2), CO2 Temperature programmed dessorption (CO2-TPD) and a model reaction, the dehydrogenation of cyclohexane, was used to evaluate the dispersion of nickel particles. The samples supported on Al2O3-C presented larger values of BET surface areas. XRD analysis showed the formation of a CeZrO2 solid solution. TPR results showed that the presence of cerium and cerium-zirconium oxides promoted the reduction of NiO, increasing the reducibility of the respective catalysts. CO2-TPD analysis indicated the presence of basic sites and of redox sites and that both the support as well as the reduced nickel, quimissorved CO2. The catalysts supported on Al2O3-C presented better nickel dispersions, measured by dehydrogenation of cyclohexane reaction. Light-off curves showed that autothermal reforming of methane occurred by indirect mechanism, which consisted on combustion at lower temperatures, with the posterior reforming of methane by CO2 or H2O at higher temperatures. The catalytic tests of long duration presented, for the majority of the tested samples, good activity, stability and high hydrogen selectivity. CeO2 and CeZrO2 had an important role for the stability of the samples, helping in the regeneration of catalytic surface. The H2/CO ratios were around 2.5 for all the samples, which is a good value for the autothermal reforming of methane. The samples supported on Al2O3-C had presented higher H2/CO ratios. Ni/CeZrO2/Al2O3-C catalyst showed the best activity and this performance is coherent with the results of TPR, which presented higher reduticibility and higher nickel dispesion.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Universidade Federal do Triângulo Mineiro

In this work the crystallization of citric acid using Tahiti lemon juice was studied. The experiments were carried out in a batch crystallizer, with agitation and temperature control. The influences of three variables according to a composite experimental design on the production of citric acid were analyzed: super saturation, crystal number (seeding) and speed stirred. The effects of these variables and their interactions were analyzed by the response surface methodology. The biggest influences were exerted by supersaturation and by speed stirred. Through a canonic analysis of the adjusted response surface, the optimal variables values that led to the biggest production of citric acid were determined: R = 356 rpm (speed stirred); S = 1.26 super saturation and N = 27 seeding. In these conditions, the relations of the crystal mass and seed mass for citric acid (y) reached 2.2700. A kinetic study into the growth from the crystal of citric acid showed that the average increase of the mass of crystals was 1.375x10-6 kg (102% of the initial mass) and it showed presented an average increase of the characteristic dimensions of 0.48x10-3 m after two hours of crystallization. The calculated growth rate decreases throughout the time, probably because of the reduction of the driving force and for the dependence that the growth rate of crystals has in related to the size of the same ones. Being that lesser crystals possess bigger growth rate that the crystals biggest not following. The smaller crystals show a larger growth rate than the bigger crystals and crystallization didn t follow the McCabe ΔL law. The kinetic study of the growth rate showed that KG changed through the experiments, probably because of hydrodynamic influence in the agitation, that is, bigger particles behave in a different way from smaller particles on the crystallizer in a certain agitation.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The flotation made by dissolved air (DFA) is an effective technology on the removal of the phosphorus during the treatment of the sewage system. The city of Uberlândia, nowadays, treats the whole domestic sewage, through three stations equipped with anaerobic reactors followed by the units of flotation. The sewage systems normally present between 4 and 15 mg / L of phosphate (METCALF; EDDY,1991). The phosphorus that is found in the sewage system under the format of phosphate is the most important limiting factor of the productivity in the most of the continental waters, being responsible for the artificial eutrophication . It s necessary to promote the chemical coagulation and the flocculation of the scattered particles in the water so that the flotation of the sewage system becomes successful. The hydrophobicity, the presence of micro air bubbles, and the chemical products added to the tributary, are also essential factors in the flotation process. The operation of flotation unit involves many variables, and the most important are the outflow of the air, the velocity of the dredging machine, the concentration of coagulant and polymer. This way, the planning and analysis of the experiments are more trustworthy, when statistic techniques are used. The determination of a relationship between the variables of the process and the removal of phosphorus provides a better evaluation of the efficiency of the flotation unit. From this perspective, a central compound planning was made to determine the equation of the removal of the phosphorus because of the outflow of the air, the velocity of the dredging machine, the concentration of coagulant and polymer. According to the main experimental results the average of the efficiency was 85% on the flotation unit, which provided an improvement of the environmental quality of the hydric body that receives the treated effluents. The variables of the concentration of coagulant and the outflow of the air influence significantly on the removal of the phosphorus. The cationic polymer used through this work did not prove efficient on the treatment of the pos reactor effluent. The best operational conditions for ETEIpanema were determined on the intermediary level of the experimental range used ( the concentration of coagulant of 80 ppm, the polymer concentration of 2,5 ppm, the velocity of the dredging machine of 1,15 RPM and the outflow of the air of 20 L/s), since high values of phosphorus removal was reached together with a decrease of the use of inputs and a lesser wearing of the unit of flotation.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

The dimensioning, the modeling and the simulation of the rotary dryers constitutes a big challenge. The drying involves mass and heat transfer, and fluid dynamics processes of the most different forms. Great part of the dryers projects are done according to empiricism and based on the experience of engineers and on the scale-up of prototypes. The purpose of this piece of work was: to analyze the equations, the models and the project proposals on drying found in the literature about rotary dryers, using for this analysis experimental dada obtained by drying granulated fertilizers GTSP in a conventional industrial cocurrent rotary dryer (3m in diameter x 30m in length). Having collected the operational data (variables of the process) and obtained the results, it is carried out an analysis of the project proposals of the rotary dryers and of the drying models evaluated according to other pieces of work of the same kind (ARRUDA, 2008 and CRISTO, 2004). Besides it is also identified the prediction parameters of residence time, the coefficient of heat transfer and others fluid dynamics information. In the presence of the fact that experimental tests were accomplished in an industrial equipment, there were limitations regarding the parameter variation. The equipment dimensions are fixed (industrial unit) and other parameters are variables that guarantee the quality and the productivity of the industrial unity. Hence, the equipment rotation is a parameter able to be analyzed once there is, exceptionally in the equipment in which the tests were accomplished, a rotation control that enables, according to the structural limitations of the equipment, a variation of 20% of its nominal rotation. The tests were accomplished using dryer rotations of 3.5 and 4.2 rpm. The results which were obtained according to the behavior of the fluid dynamics of the material in the interior of the dryer, presented good concurrence with the models shown in the literature. To determine the flight holdup distribution and the behavior of the material cascading in the inner part of the dryer (time, height and average angle of the fall), the methodology REVOL et al. (2001) presented quite consistent information concerning the prediction, using the friction coefficient determined experimentally of 0.746 for the GTSP. In order to determine the residence time, the equation that fitted best to the experimental results was FRIEDMAN and MARSHALL S (1949) Equation with parameters estimated by ARRUDA (2008). The results that were obtained for the mass balance and energy were quite consistent and they made clear a quite pertinent situation related to the project considerations that deal with the premises of false air entrances. In order to determine the global coefficients of heat transfer, the equation that best foresaw this parameter is the one presented by MILLER et al. (1942), pondering the reduction of the temperature of the gases in the beginning of the dryer which was caused by the false air entrances. The modeling proposed by ARRRUDA (2008) presented significative deflections according to the experimental results. They were possibly caused by imprecision while measuring, by premises of false air entrances (loses) and/or by possible differences related to the behavior of the materials used in ARRUDA S tests (2008) and the ones used in the experiments. The application of the Methodology I (VAN T LAND, 1991) presented inconsistencies in the project opposing the approach of false air entrances mentioned before. The Methodology II (NONHEBEL and MOSS, 1971) does not presume the knowledge of the drying curve of the material. Thus, the results obtained in ARRUDA (2008) were used. As it happened to Methodology I, inconsistencies in the project were found. However, the profiles of the coefficients of mass and heat transfer traced with the results that were obtained in ARRUDA (2008) presented a kind of behavior with physically expected tendencies.