Carlos Henrique Ataíde

Modeling and experimental study of hydrodynamic and drying characteristics of an industrial rotary dryer

The purpose of this work was to analyze the hydrodynamic and drying aspects of a rotary dryer used in a fertilizer industry. A set of equations to predict the solids holdup in the flights, the length of fall, the residence time of particles and the drying variables was evaluated by comparison to experimental measurements performed in an industrial rotary dryer of the Copebras Fertilizer Company, located in Catalao, state of Goias, Center-west of Brazil. Because of precise estimations, these equations may be used to design and predict the solids cascading behavior in industrial rotary dryers. Despite larger deviations, reaching 20%, the drying model can also be used for design calculations and process simulations.

Flotation Selectivity of Phosphate Ore: Effects of Particle Size and Reagent Concentration

The flotation selectivity of apatite particles from a carbonatite complex was investigated in a flotation column as a function of particle size and reagent concentrations. Experiments were performed according to a factorial experimental design. Fine and coarse particles showed different sensitivities to variations in the concentration of the reagent. Coarser particles showed a higher selectivity ratio and greater sensitivity to the addition of different reagent dosages, providing a more selective separation and a better quality product. Finer particles presented lower selectivity ratios, reflecting the difficulty involved in the concentration process with this particle size.

Effects of Operating Variables on the Yeast Separation Process in a Hydrocyclone

This work involved the use of a hydrocyclone to separate yeast from alcoholic fermentation suspensions. The performance of the hydrocyclone was quantified using empirical models that describe the capacity, total separation efficiency, flow ratio, and reduced separation efficiency as a function of the concentration of the suspension and the operating pressure drop. The results showed capacities of 0.1283 to 0.1820 m3/h, total separation efficiencies of 81.96% to 92.19%, reduced separation efficiencies of 0.63% to 58.44%, and flow ratios ranging from 81.05% to 84.85%.

Physical Characterization and Biomass Fluidization (Fume Powder)

The development of big cities and industrialization has been causing environmental degradation problems, damaging natural and energetic resources, besides the bigger production of wastes. So, it is essential the use of renewable alternative fuels, and industrial wastes processing. Biomass can be used in direct combustion, thermo chemical and biological processes. The fume powder is an important waste of tobacco industries. This work makes a characterization of fume powder, originated from Souza Cruz (Uberlândia unit); the objective is to realize the fast pyrolysis in a bubble fluidized bed. Physical analyses of the powder were made to determine the size distribution, and the medium diameter; the solids density and moisture content (dry base). The elementary composition of the material was also determined. The powder fluidization in an acrylic bed (160 cm heights, 10 cm id), was realized to obtain the minimum fluidization velocity.

Influence of the Water Composition on the Selectivity of Apatite Flotation

The effect of ionic species on the flotation selectivity of apatite was evaluated. Water containing fluoride, calcium, magnesium, and phosphate was used in the flotation experiments carried out in a flotation column for coarse and fine phosphate ore. The selectivity of apatite over ferrous and siliceous gangue was investigated. Coarse and fine ores showed different sensitivities according to the ion concentration. The results clearly showed the harmful effect of the ionic species under study on apatite selectivity. The contaminants responsible for the lowest selectivity ratios for ferrous and silicate gangue were calcium and magnesium, regardless of particle size.

Determination of the Chemical and Mineralogical Composition of Drilled Cuttings at Different Points throughout the Solids Control Process

In this work, we use x-ray fluorescence and x-ray diffraction methods to investigate the chemical and mineralogical composition of drilled cuttings at different points throughout the solids control process. Cuttings coated or contaminated with drilling fluid are the result of drilling. Over the past twenty years, studies have been conducted to assess the effects that these contaminated cuttings have on the environment, in both offshore and onshore scenarios. A more restrictive environmental legislation and the need to reduce drilling costs (exploration and production) has led to the optimization of solid-liquid separation. Knowledge of the chemical and mineralogical composition of drilled cuttings will assist in finding a dispersant and in determining an appropriate procedure for carrying out particle size analysis of these solids.

Kinetics of microwave heating and drying of drilling fluids and drill cuttings

ABSTRACT Drill cutting decontamination by microwave drying has been studied over the past few years and has proved to be a promising technology. This study aimed to investigate fundamental aspects of kinetics of heating and drying of drilling fluids and drill cuttings by microwaves. The microwave heating curve of cuttings free of fluid, drilling fluids, and pure organic compounds usually used in the formulation of these fluids was evaluated to understand the behavior of each component in microwave cutting decontamination. Furthermore, commercial software was used to describe the heating kinetics of the drilling fluids used in this study. The drying kinetics of cuttings contaminated with these drilling fluids was also studied at three temperatures of control. Some classic models of conventional drying of solids were used to describe the removal kinetics of the liquid components present in contaminated cuttings (water and organic compounds). Important aspects related to the interaction of these components in the drying operation and solid heating, water evaporation, and the drag of organic compounds were investigated. Both drilling fluids showed a very similar kinetic heating. Pure organic bases did not show a significant heating. For the same drying time, the removal of paraffin is more intense than the olefin. In respect to organic component removal from cuttings contaminated with both fluids, the kinetic drying curves are similar. The Page model was the one that best describes the drying operation of drill cuttings contaminated with both drilling fluids. The microwave drying model (MDM) model is proposed in this work as a simple modification in the Henderson–Pabis model: the addition of a third parameter. The incorporation of this parameter enabled a better fit of the experimental data. Computational simulations show an electric field with symmetrical patterns for the two BR-MUL fluids analyzed.

Size, Shape and Density Characterization of Tobacco Waste Particles

There is an increasing concern about environmental problems associated with the rising emissions of CO2, NOx and SOx due to the use of fossil fuels. Thus, renewable energy based on biomass could contribute to relieve the environmental and energy problems. Biomass energy conversion covers the processing of industrial and agricultural wastes, taking advantage of materials that would be discarded. In this work, tobacco residue characterization is studied; the material is a waste of tobacco industry. Values of true density were inferred for three different ranges of particle sizes and particles size and shape were studied for the three set of particles using dynamic digital image processing. The results show differences in physical characteristics of the biomass, varying the particle size.

Physical Properties of Cuttings, Drilling Fluid and Organic Phase Recovered in the Drying Operation in Oil and Gas Well Drilling

Oil companies have increasingly invested in alternative technologies for cuttings treatment. The research for new operations or equipments leads to investigate the properties and characteristics of drilled cuttings and drilling fluids. This work presents the physical characterization of cuttings, drilling fluid and organic phase recoved after cuttings drying. It was carried out analysis of rheology for the drilling fluid and particle size and shape for the cuttings. Considering the microwave drying technology, which has been investigated for cuttings treatment, it was also determined the dielectric properties for the drilling fluid. The quality of the organic phase recovered in the microwave cuttings drying was also analysed.

CFD Applied to the Analysis of Hydrodynamics in a Hydrocyclone

Although the construction, maintenance and operation of hydrocyclones is simple in nature, it is known that the hydrodynamic behavior inside hydrocyclones is quite complex. Among the features which confer this complexity stands out: high vorticity preservation, vortex breakdown, flow inversion, and the possibility of formation of air core due to the generation of a low pressure area in the central axis of the separator. In this sense this work aimed to study the hydrodynamics of a hydrocyclone using as tool the Computational Fluid Dynamics (CFD). The simulated results were obtained considering two different models for turbulence: Reynolds stress model and Large Eddy simulation methodology. Can be highlighted as main simulated variables the flow ratio and the pressure drop of the hydrocyclone, which were compared with experimental values. In order to evaluate the influence of air core on the simulated variables, were done numerical simulations of the hydrocyclone operating in the presence of air core, using for this, the volume of fluid (VOF) model.