ABSTRACT The relative importance of design variables affecting the fluiddynamic behavior of a fluidized bed reactor for the gas-phase ethylene polymerization is discussed, based on mathematical modeling. The three-phase bubbling fluidized... more
ABSTRACT The relative importance of design variables affecting the fluiddynamic behavior of a fluidized bed reactor for the gas-phase ethylene polymerization is discussed, based on mathematical modeling. The three-phase bubbling fluidized bed model is based on axially distributed properties for the bubble, cloud and emulsion phases, combined with correlations for population balance and entrainment. Under the operating conditions adopted in most industrial processes, the reactor performance is affected mainly by the reaction rate and solids entrainment. Simulation results indicate that an adequate design of the freeboard and particle collecting equipment is of primary importance in order to produce polymeric particles with the desired size distribution, as well as to keep entrainment and catalyst feed rates at adequate levels.
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... Antonio CSC Teixeira1, Giselle Stollar, Roberto Guardani, Cláudio AO Nascimento University of São Paulo Chemical Engineering Department Av. Prof. Luciano Gualberto, tr. 3, 380 - 05508-900 - São Paulo SP Brazil Fax:... more
... Antonio CSC Teixeira1, Giselle Stollar, Roberto Guardani, Cláudio AO Nascimento University of São Paulo Chemical Engineering Department Av. Prof. Luciano Gualberto, tr. 3, 380 - 05508-900 - São Paulo SP Brazil Fax: +55-11-3813-2380 1 E-mail: acscteix@usp.br ...
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Eficiência agronômica de termofosfatos magnesianos fundidos produzidos com rocha fosfática de Maicuru, em casa de vetetaçao;[Eficiencia agronómica de termofosfatos magnesianos fundidos con roca fosfórica, producidos con roca fosfórica de Maicuru, en condiciones de invernadero].[Agronomic efficien...more
ABSTRACT: This paper presents results of air quality monitoring campaigns carried out in the industrial city of Cubatão, based on the Lidar methodology. The interest in these monitoring campaigns is related to the specific situation of... more
ABSTRACT: This paper presents results of air quality monitoring campaigns carried out in the industrial city of Cubatão, based on the Lidar methodology. The interest in these monitoring campaigns is related to the specific situation of Cubatão as one of the largest ...
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The degradation of a biologically persistent aminosilicone polymer (PDMAS) formulation, used in the textile industry as a softener of polyester fabrics, was investigated using the Fenton and the photochemically enhanced Fenton reactions.... more
The degradation of a biologically persistent aminosilicone polymer (PDMAS) formulation, used in the textile industry as a softener of polyester fabrics, was investigated using the Fenton and the photochemically enhanced Fenton reactions. Experiments were performed using a ...
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Among advanced oxidation processes (AOPs), the photochemically enhanced Fenton reaction may be considered as one of the most efficient for the degradation of contaminants in industrial wastewater. This process involves a series of complex... more
Among advanced oxidation processes (AOPs), the photochemically enhanced Fenton reaction may be considered as one of the most efficient for the degradation of contaminants in industrial wastewater. This process involves a series of complex reactions. Therefore, an empirical model based on artificial neural networks has been developed for fitting the experimental data obtained in a laboratory batch reactor for the degradation of 2,4-dimethyl aniline (2,4-xylidine), chosen as a model pollutant. The model describes the evolution of the pollutant concentration during irradiation time as a function of the process conditions. It has been used for simulating the behavior of the reaction system in sensitivity studies aimed at optimizing the amounts of reactants employed in the process, an iron(III) salt and hydrogen peroxide, as well as the temperature. The results show that the process is most sensitive to the concentration of iron(III) salt and temperature, whereas the concentration of hyd...
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ABSTRACT Optical remote sensing techniques have obvious advantages for monitoring gas and aerosol emissions, since they enable the operation over large distances, far from hostile environments, and fast processing of the measured signal.... more
ABSTRACT Optical remote sensing techniques have obvious advantages for monitoring gas and aerosol emissions, since they enable the operation over large distances, far from hostile environments, and fast processing of the measured signal. In this study two remote sensing devices, namely a Lidar (Light Detection and Ranging) for monitoring the vertical profile of backscattered light intensity, and a Sodar (Acoustic Radar, Sound Detection and Ranging) for monitoring the vertical profile of the wind vector were operated during specific periods. The acquired data were processed and compared with data of air quality obtained from ground level monitoring stations, in order to verify the possibility of using the remote sensing techniques to monitor industrial emissions. The campaigns were carried out in the area of the Environmental Research Center (Cepema) of the University of Sao Paulo, in the city of Cubatao, Brazil, a large industrial site, where numerous different industries are located, including an oil refinery, a steel plant, as well as fertilizer, cement and chemical/petrochemical plants. The local environmental problems caused by the industrial activities are aggravated by the climate and topography of the site, unfavorable to pollutant dispersion. Results of a campaign are presented for a 24- hour period, showing data of a Lidar, an air quality monitoring station and a Sodar.
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We have investigated the kinetics of the degradation of 2,4-dimethyl aniline (2,4-xylidine), chosen as a model pollutant, by the photochemically enhanced Fenton reaction. This process, which may be efficiently applied to the treatment of... more
We have investigated the kinetics of the degradation of 2,4-dimethyl aniline (2,4-xylidine), chosen as a model pollutant, by the photochemically enhanced Fenton reaction. This process, which may be efficiently applied to the treatment of industrial waste waters, involves a series of ...
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ABSTRACT Emulsified fluids are used in many industrial and consumer areas, for instance as products in the food or health industry as well as technical fluids in the machining industry. Metalworkingfluids (MWF) are used as coolants and... more
ABSTRACT Emulsified fluids are used in many industrial and consumer areas, for instance as products in the food or health industry as well as technical fluids in the machining industry. Metalworkingfluids (MWF) are used as coolants and lubricants in metalworking processes. During their usage MWF emulsions may change their physical and chemical properties, which influences their performance and decrease the physical stability and therefore their lifetime. This article discusses results of turbidimetric spectra measurement of MWF emulsions to be used for process control, MWF quality monitoring and formulation purposes. Therefore, laboratory experiments have been carried out investigating the physical stability. Metal working emulsions have been treated and destabilised by different concentrations of salts. The destabilisation process was monitored by undiluted turbidity measurements and evaluated by the temporal change of the wavelength exponent. Thus, it was possible to determine specific conditions, for example a specific critical salt concentration for maintaining, stability of the MWF formulations.
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A numerical model is proposed for the complex flow of a bubble column reactor. The study was carried out in a two-dimensional dynamic simulation performed in the commercial software Fluent 2019 R2. The Euler-Euler multiphase model with... more
A numerical model is proposed for the complex flow of a bubble column reactor. The study was carried out in a two-dimensional dynamic simulation performed in the commercial software Fluent 2019 R2. The Euler-Euler multiphase model with interaction forces source terms was employed as well as the κ-ε turbulence model. The bubbleinduced turbulence (BIT) models of Simonin and Viollet (1990) and Troshko and Hassan (2001) were investigated and compared to the zero source term standard κ-ε model. The sensitivity of both BIT models in respect to their respective coefficients (𝐶𝑠, 𝐶𝑘𝑒 and 𝐶𝑡𝑑) is also studied. Different bubble sizes were tested in the Eulerian multiphase model in order to optimize the numerical results. The simulations were validated with experimental data for a bubble column presented in the literature by Sheng and Iron (1993).
A numerical model is proposed for the complex flow of a bubble column reactor. The study was carried out in a two-dimensional dynamic simulation performed in the commercial software Fluent 2019 R2. The Euler-Euler multiphase model with... more
A numerical model is proposed for the complex flow of a bubble column reactor. The study was carried out in a two-dimensional dynamic simulation performed in the commercial software Fluent 2019 R2. The Euler-Euler multiphase model with interaction forces source terms was employed as well as the κ-ε turbulence model. The bubbleinduced turbulence (BIT) models of Simonin and Viollet (1990) and Troshko and Hassan (2001) were investigated and compared to the zero source term standard κ-ε model. The sensitivity of both BIT models in respect to their respective coefficients (𝐶𝑠, 𝐶𝑘𝑒 and 𝐶𝑡𝑑) is also studied. Different bubble sizes were tested in the Eulerian multiphase model in order to optimize the numerical results. The simulations were validated with experimental data for a bubble column presented in the literature by Sheng and Iron (1993).
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... Powder Technology, 56 (1988) 41 - 48 Characterization of Flow Regime Transitions in a ... INTRODUCTION An increasing popularity of circulating fluidized bed (CFB) reactors has been observed in the ... years in the field of both... more
... Powder Technology, 56 (1988) 41 - 48 Characterization of Flow Regime Transitions in a ... INTRODUCTION An increasing popularity of circulating fluidized bed (CFB) reactors has been observed in the ... years in the field of both catalytic and non-catalytic gas-solid reactions (for ...
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This paper presents results of laboratory tests aimed at studying the thermal transformations of aluminum phosphate rock samples from North/Northeast Brazil. The thermal decomposition which takes place from 170 to 500°C leading to the... more
This paper presents results of laboratory tests aimed at studying the thermal transformations of aluminum phosphate rock samples from North/Northeast Brazil. The thermal decomposition which takes place from 170 to 500°C leading to the solubilization of P2O5 was studied in calcination tests in two types of laboratory-scale reactors: classical fluidized bed and circulating (fast) fluidized bed. The results of continuous
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ABSTRACT The physical stability of emulsions can be related to changes in the droplet size distribution over time. Stability control of emulsions used as metal working fluids is an important factor for the machining industry due to the... more
ABSTRACT The physical stability of emulsions can be related to changes in the droplet size distribution over time. Stability control of emulsions used as metal working fluids is an important factor for the machining industry due to the decreased perfor-mance of aged and broken emulsions. Results of turbidimetric spectra measure-ments of metal working fluids for process control purposes and emulsion stability monitoring are discussed. Metal working emulsions were artificially destabilized by admixing salts which resulted in droplet coagulation. The destabilization pro-cess was investigated by measuring the droplet size distribution and the turbidity spectra over time. The results were evaluated based on quantitative criteria pro-posed in the literature. The applicability of these criteria to evaluate metal work-ing fluids during machining operations is discussed.