Papers by Author: João Jorge Ribeiro Damasceno

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Authors: Fábio de Oliveira Arouca, Marcos A.S. Barrozo, João Jorge Ribeiro Damasceno
Abstract: The determination of the grade distribution of solid particles is fundamental for the performance analysis of several pieces of equipment promoting the solid-fluid separation. The main objective of this work is to compare the results obtained for two traditional methodologies for determination of the sized grade distribution of powdery solids: the gamma rays attenuation technique (GRAT) and LADEQ test tube technique. The influence of draining of suspension in the two used techniques was also analyzed. The gamma rays attenuation technique can supply the grade distribution of solids through the monitoring of solid concentration in experiments of batch settling of diluted suspensions. The results show that the usage of the peristaltic pump in GRAT and LADEQ methodologies presented a significant difference among the values obtained for the parameters of the particles size model.
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Authors: Fábio de Oliveira Arouca, C.G. Azevedo, M.H.A. Oliveira, João Jorge Ribeiro Damasceno
Abstract: The dynamic analysis of behavior of solid particles in porous media such as settling processes are important for the dimensioning increasingly precise of pieces of equipment that promote the solid-liquid separation. Several factors can influence in dynamics of the fall of solid particles into a fluid medium; among them, the shape, distribution of sizes, and particle density. The main objective of this work is to analyze the behavior of solid-solid system based on the shape, size distribution and density of solid particles. The initial settling velocity in batch settling tests and the accommodation of particles in the sediment formed are evaluated for different materials. The gamma-ray attenuation technique was used in the experimental tests. Comparison of results obtained allowed evaluating in an exploratory research the significance of variables involved.
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Authors: A.F. Lacerda, M.R. Moroti, Marcos A.S. Barrozo, João Jorge Ribeiro Damasceno
Abstract: The cyclones are one of the most known apparatus destined to the solid-gas separation. These equipments are used in the chemistry industry; its popularity is due mainly to the simplicity, low energy requirements and ability to operate at high temperatures and pressures. One of the aims of this work was to evaluate the influence of some geometrics variables in the performance of conventional cyclones and filtering cyclones. The chosen variables were: conic part length (Zc), the underflow diameter (Du), the overflow diameter (Do) and the finder length (Sc). The cyclones conventional and with filter were compared and it was observed that the introduction of a filter main in substitution to the metallic conic part of cyclones allows a appreciable reduction in the pressure drop and consequently a smaller consumption of energy. The efficiency in the new cyclone was a little smaller than the conventional equipment.
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Authors: Luiz Gustavo Martins Vieira, João Jorge Ribeiro Damasceno, Marcos A.S. Barrozo
Abstract: Hydrocyclones are centrifugal devices employed on the solid-liquid and liquid-liquid separation. The operation and building of these devices are relatively simple, however the flow inside them is totally complex and its prediction is very difficult. The fluid moves on all possible directions (axial, radial and swirl), the effects of turbulence can not negligible and an air core along the center line of the hydrocyclone can appear when the operational conditions are favorable. For that reason, the most models that are used to predict the hydrocyclone performance are empirical and require the collection of the main operational and geometric variables in order to validate them. This work objectified to apply Computational Fluid Dynamics (CFD) on Bradley Hydrocyclone and compare the results from this technique to empirical models. The numerical simulation was made in a computational code called Fluent® that solves the transport equation by finite volume technique. The turbulence was described by Reynolds Stress Model (RSM) and the liquid-gas interface was treated by Volume of Fluid Model (VOF). In agreement with the results from the simulation, it was possible to predict the internal profiles of velocity, pressure, air core, particle trajectories, efficiencies, pressure drop and underflow-to-throughput ratio.
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Authors: Luiz Gustavo Martins Vieira, João Jorge Ribeiro Damasceno, Marcos A.S. Barrozo
Abstract: Hydrocyclones are centrifugal devices employed on the solid-liquid and liquid-liquid separation. The operation and building of these devices are relatively simple, however the flow inside them is totally complex and its prediction is very difficult. The fluid moves on all possible directions (axial, radial and swirl), the effects of turbulence can not negligible and an air core along the center line of the hydrocyclone can appear when the operational conditions are favorable. For that reason, the most models that are used to predict the hydrocyclone performance are empirical and require the collection of the main operational and geometric variables in order to validate them. This work objectified to apply Computational Fluid Dynamics (CFD) on Bradley Hydrocyclone and compare the results from this technique to empirical models. The numerical simulation was made in a computational code called Fluent® that solves the transport equation by finite volume technique. The turbulence was described by Reynolds Stress Model (RSM) and the liquid-gas interface was treated by Volume of Fluid Model (VOF). In agreement with the results from the simulation, it was possible to predict the internal profiles of velocity, pressure, air core, particle trajectories, efficiencies, pressure drop and underflow-to-throughput ratio.
376
Authors: A.F. Lacerda, Luiz Gustavo Martins Vieira, A.M. Nascimento, S.D. Nascimento, João Jorge Ribeiro Damasceno, Marcos A.S. Barrozo
Abstract: A two-dimensional fluidynamics model for turbulent flow of gas in cyclones is used to evaluate the importance of the anisotropic of the Reynolds stress components. This study presents consisted in to simulate through computational fluid dynamics (CFD) package the operation of the Lapple cyclone. Yields of velocity obtained starting from a model anisotropic of the Reynolds stress are compared with experimental data of the literature, as form of validating the results obtained through the use of the Computational fluid dynamics (Fluent). The experimental data of the axial and swirl velocities validate numeric results obtained by the model.
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Authors: Fábio de Oliveira Arouca, L.C.O. Lopes, João Jorge Ribeiro Damasceno
Abstract: Knowledge of particle concentration is of extreme importance for the settling phenomenon. For well-diluted suspensions the solids concentration can be measured by sampling techniques. However, the use of such a technique for more concentrated suspension does not lead to good results. Knowledge of concentration distribution in sediments formed by decantation of aqueous suspensions inside a vertical vessel is fundamental for the evaluation of performance of some pieces of equipment such as continuous thickeners. In this work, the phenomenon of batch settling of aqueous suspensions of calcium carbonate was studied by using a nondestructive technique based upon the measurement of gamma-ray attenuation when the radiation beam goes through the physical medium as a function of the local concentration in several vertical positions of the vessel, and the sampling of suspension by aliquots is not necessary. The main objective of this work is to evaluate the use of gammaray attenuation technique for achieving concentration distributions in the phenomenon of batch settling as well as curves of iso-concentrations.
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Authors: Edu A. Barbosa, Luiz Gustavo Martins Vieira, Celso A.K. Almeida, João Jorge Ribeiro Damasceno, Marcos A.S. Barrozo
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Authors: L. Meili, M.O. Fernandes, Carlos Henrique Ataíde, João Jorge Ribeiro Damasceno
Abstract: The Venturi scrubbers have a high collection efficiency to remove very small particles from gaseous streams. The main purpose of this work is to determine the overall collection efficiency of Venturi scrubbers with circular section under different operation conditions. The experimental system consisted of a Venturi scrubber with circular section and liquid injection in the throat. A factorial experimental design was carried out; the overall collection efficiency was the response. Three variables were analyzed: the throat length, the air velocity and the liquid flow. The best values for efficiency were obtained for 15 m/s of air velocity and 300 mL/min of liquid flow and the throat length did not have influence.
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