José Luis de Paiva - Academia.edu (original) (raw)
Papers by José Luis de Paiva
Chemical engineering transactions, Apr 20, 2011
The aim is to show a methodology to characterize the cooling tower performance, when submitted to... more The aim is to show a methodology to characterize the cooling tower performance, when submitted to diverse operational conditions. The experiments were carried out in a pilot plant and a correlation between the cooling tower performance and the principal process variables (air and water mass flow rates) was obtained. The methodology developed can be applied in industrial cooling towers because the measures are usually available in typical plants. A parametric simulation study was developed to investigate the influence of gas flow rate, liquid flow rate and cooling water height of filling in the thermal demand of a cooling water system. The proposed study and analysis should be useful for performance analysis of real-world cooling water and the Management of Cooling Tower System.
Chemical engineering transactions, Apr 20, 2011
The process for removing carbon dioxide from industrial gases can be achieved by absorption into ... more The process for removing carbon dioxide from industrial gases can be achieved by absorption into aqueous solutions of alkanolamines. Mass transfer parameters in different alkanolamines solutions were investigated in a wetted wall column with a film promoter of thin stainless steel woven wire. The average overall volumetric mass transfer coefficient was measured at 25 ºC, atmospheric pressure. The total gas flow rate at 2.8. 10-4 m 3 /s, with a composition of 10 % CO 2 , was also measured in different liquid flow rates. The tested alkanolamines in the different experiments were monoethanolamine (MEA) and 2-amine-2-methyl-1 propanol (AMP). The absorption experiments were performed in individual alkanolamines aqueous solutions and their respective blends, aiming to combine the favorable features of individual alkanolamines while reducing the unfavorable features. The effective interfacial area of the column, a e , was determinated through the absorption of CO 2 diluted in air with an aqueous solution of NaOH, 2N, for different liquid flow rates. The results indicate that the average overall volumetric coefficients of mass transfer of the MEA and the mixture based on it are higher in relation to AMP. Moreover, this parameter is significantly affected by the behaviour of the film liquid flow rate provided by the film promoter, thus, affecting the efficiency of CO 2 removal.
Chemical Engineering and Processing, Nov 1, 2013
The process for removing carbon dioxide from industrial gases can be achieved by absorption into ... more The process for removing carbon dioxide from industrial gases can be achieved by absorption into aqueous solutions of alkanolamines. Mass transfer parameters in different alkanolamines solutions were investigated in a wetted wall column with a film promoter of thin stainless steel woven wire. The average overall volumetric mass transfer coefficient was measured at 25 ºC, atmospheric pressure. The total gas flow rate at 2.8. 10-4 m 3 /s, with a composition of 10 % CO 2 , was also measured in different liquid flow rates. The tested alkanolamines in the different experiments were monoethanolamine (MEA) and 2-amine-2-methyl-1 propanol (AMP). The absorption experiments were performed in individual alkanolamines aqueous solutions and their respective blends, aiming to combine the favorable features of individual alkanolamines while reducing the unfavorable features. The effective interfacial area of the column, a e , was determinated through the absorption of CO 2 diluted in air with an aqueous solution of NaOH, 2N, for different liquid flow rates. The results indicate that the average overall volumetric coefficients of mass transfer of the MEA and the mixture based on it are higher in relation to AMP. Moreover, this parameter is significantly affected by the behaviour of the film liquid flow rate provided by the film promoter, thus, affecting the efficiency of CO 2 removal.
Esta obra apresenta a disciplina de probabilidades em um status especial entre as demais em um cu... more Esta obra apresenta a disciplina de probabilidades em um status especial entre as demais em um curso de engenharia. Sua posição pode ser compreendida quando contemplamos o desenvolvimento das ciências aplicadas ao longo da história. Todas essas mudanças estão ligadas à mudança de paradigmas que ocorreu na transição entre os séculos 19 e 20, período rico também em convulsões sociais, entre elas a formação de vários estados modernos e várias revoluções. Basta mencionar o da Alemanha, Itália, a Revolução Meiji, a independência de nosso país e de outros, a revolução russa e a Primeira Guerra. Um curso de probabilidades para engenharia marca essa transição histórica e oferece uma visão de mundo diferente, em que se coloca uma ordem no caos.
XVI COBEQ; III CBTERMO:engenharia química & inovação : anais Lorena : EEL-USP/UNICAMP/ABEQ, 2006, 2006
VI COBEQ-IC : programação e resumos, 2005
Computer-aided chemical engineering, 2023
Industrial & Engineering Chemistry Research, Oct 7, 2022
Fluids, Feb 23, 2017
Working fluids possess several applications in manufacturing processes, for instance lubricants i... more Working fluids possess several applications in manufacturing processes, for instance lubricants in metals machining. Typical metal working fluids are formulated as oil-in-water emulsions. The maintenance of the physical stability of the working fluid during operation is a key factor for the sustainability of the relevant process. Therefore, continuous control of the working fluids stability and performance during machine operation is an essential tool for maintenance of the process performance. Turbidity measurement (TM) is a process technique for emulsion stability and quality assessment, where light transmission and absorption of an emulsion system is analyzed. However, for in-process measurement and fluid quality detection during the machine operation by TM, it is necessary to implement a transmission inline sensor into the working fluid flow line. The continuous flow measurement may cause problems for long-term sensor operation regarding, e.g., biofouling of the sensor optical glasses or erroneous measurements due to emulsion droplets segregation effects. In the present investigation, computational fluid dynamic (CFD) simulations have been adapted to obtain the emulsion flow conditions within a typical TM sensor probe, thereby allowing an assessment of the adhesion probability of microorganisms as well as droplet segregation effects. The simulation results indicate some temporal changes of the dispersed phase concentration in the detected emulsion flow. Due to droplet segregation in the emulsion, the flow velocity needs to exceed a certain value for reliable operation. It is shown here that in this flow regime microbiological attachments on the probe surfaces may be sufficiently avoided. A minimum critical flow velocity is derived to avoid biomolecule adhesion and thus durable operation of the sensor.
International Conference on Liquid Atomization and Spray Systems (ICLASS), 2021
Sprays of molten metal are known to exhibit rich spatio-temporal dynamics, such as a pulsating me... more Sprays of molten metal are known to exhibit rich spatio-temporal dynamics, such as a pulsating metal mass flux, or a precession motion of the melt plume. Powerful tools for their investigation are high-speed recordings combined with digital image processing. In this work, we present a method to generate spatio-temporal diagrams from the recordings. These diagrams are ideally suited to quantify spray fluctuations in space and time. Experiments were conducted in an annular close-coupled atomizer using a copper alloy (CuSn6) as base material with varying atomization gas pressures ([0.8, 1.2, 1.6, 2.0] MPa) and temperatures ([293, 423, 523] K). The region of the primary atomization was monitored with a high-speed camera recording 21,800 frames per second. At the parameters investigated we observe an oscillation of the spray boundaries below 100 Hz indicating a slow precession motion. The analysis of the statistically steady spray shape surprisingly reveals a breakdown of the axial symmetry at large gas pressures, whose origin is currently unknown.
SSRN Electronic Journal, 2019
This work aimed to study the chemical desorption process of CO2 in an aqueous solution of 2-amino... more This work aimed to study the chemical desorption process of CO2 in an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) carbonated blend. The desorption process was carried out on a wetted wall column with a 0.5 m long film promoter (stainless steel 28 mesh with a known surface area) and 2.2 cm diameter. The process was online monitored by infrared spectroscopy integrated with a PLS model, which allowed the quantification in the liquid phase of free AMP and PZ, PZ mono-and dicarbamate, bicarbonate and total CO2 absorbed in all its chemical forms. The model had a drawback predicting PZ at low concentrations. The desorption was measured at atmospheric pressure (0.93 atm) and at temperatures of 50, 60 and 70 °C and blends of 30/0, 25/5, 20/10 and 0/15 wt% AMP/wt% PZ respectively. A total of 16 experiments were carried out. The process flowsheet is shown at Figure 1. A solution of 500 g was prepared and carbonated to saturation. It was pre-heated to the experiment temperature and loaded through the top of the column to wet all the the film promoter. By a peristaltic pump the solution with constant flow rate of 3.5 mL•s-1 went to the top of the column, where the liquid was distributed through all the perimeter of the promoter by a distributor. About 10 % of the flow rate past through the spectrometer where the solution was simultaneously quantified. The temperature of column tube-side liquid film was maintained by a thermostatic water heat system on the shell-side. Atmospheric air at constant flow rate of 100 mL•s-1 was preheated using water vapor generated in a boiler and then was bubbled in a heated water flask to saturate it completely at the temperature of the system. Then was bubbled in the solution and fed to the bottom of the column. The CO 2 desorption experiments work in as a quasi-stationary process. The rate of CO 2 desorbed was calculated by the mass balance of CO 2 in the liquid phase and the desorption flux is determined by the ratio to mass transfer area. The CO2 concentration on the inlet gas-bottom of the column-was assumed zero and the CO2 partial pressure on the outlet top of the column was found as CO2 desorbed divided by the gas flowing through the column. The overall mass transfer coefficient (KG) was calculated by the ratio of desorption flux and the log mean CO2 partial pressure driving force. The liquid film mass transfer coefficient (kL) was found using the series resistance relationship and a correlation was used to find the gas film mass transfer (kg). The kL decreased with higher values of CO2 loadings (α). The PZ solutions shown the lowest kL values, followed by the AMP solutions, and the blend showed the highest values of kL, increasing with PZ concentration in the mixture. The temperature had no significant influence on the values of kL. Figure 2 shows kL values at 50 ºC for different compositions.
Wear, 2020
This paper reports and discusses the results of an experimental investigation on hydraulic transp... more This paper reports and discusses the results of an experimental investigation on hydraulic transportation of iron ore concentrate and its effect on slurry wear, pure erosion and pure corrosion of a carbon steel pipe. For this, a specially designed test-loop was built to simulate long distance iron ore transportation, allowing also to determine pure erosion effects by means of a specially designed cathodic protection system. Pure corrosion damage was evaluated by linear polarization measurements in filtered ore concentrate, i.e., in the absence of particles. The results revealed that pure erosion and pure corrosion effects were much lower than the measured wear, evaluated as pipe thickness loss, indicating an important synergism between erosion and corrosion. Wear damage results in microcraters aligned in the flow direction, which merge with each other likely due to enhanced electrochemical activity fed by the erosion process. Evaluation of the effect of the pumping time on the ore concentrate characteristics revealed that particles sizes decreased while the sphericity factor increased leading to lower wear rates. Finally, a mechanism explaining the pipeline wear associating erosion, corrosion and the material microstructure as well as a methodology to forecast the pipelines thickness loss as a function of the ore concentrate travelling distance were also proposed.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2018
A study on process alternatives for reducing steam consumption was carried out in a multistage ev... more A study on process alternatives for reducing steam consumption was carried out in a multistage evaporation system of a chlorine-alkali industrial complex. A phenomenological model was developed, based on the mass and energy balances and on gas-liquid equilibrium correlations for the ternary mixture of caustic soda, sodium chloride and water. The design specifications of the plant were adopted as a reference to validate the mathematical model, which comprises 153 nonlinear equations. Different process conditions were simulated by taking into account the most important process variables and their effect on steam consumption. Differently from previously published studies, in which the conservation laws are mainly focused on the heat exchangers and their optimization, the present study considers the whole multistage evaporation unit. The model also enabled to evaluate the effect of changes in the plant configuration, either by considering a side product stream at a specified concentration, designated to another production unit in the industrial complex, or by including mechanical vapor recompression, which has proven to be a better solution to reduce steam consumption from the energy and exergy points of view. Results indicate an expressive decrease in steam consumption to around 1% of the original configuration. Moreover, from the exergy perspective, if the power generation is considered, the MVR is a better choice from the energy and exergy point of view. Keywords Exergy analysis Á Caustic soda production Á Evaporation process Á Mass and energy balances List of symbols b Specific exergy (kJ/kg) B Exergy flow rate (kW) This paper is an extended and revised version of a similar work presented in the
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Lavadores Venturi são utilizados industrialmente para o controle da emissão de poluentes. Simulou... more Lavadores Venturi são utilizados industrialmente para o controle da emissão de poluentes. Simulou-se a variação de vazões de líquido e gás em lavador Venturi industrial utilizando técnicas de CFD (Fluidodinâmica Computacional). Com o auxílio do software ANSYS CFX 15.0, simulou-se o escoamento bifásico, utilizando o modelo de fluidos interpenetrantes (abordagem Euler-Euler) e o modelo de turbulência k-ε padrão. Observou-se que a variação de pressão ao longo do Venturi calculada é, de forma geral, muito próxima da prevista pelos modelos clássicos de Boll (1973) e Viswanathan (1985). No entanto, para algumas condições de vazão de gás e líquido, observaram-se diferenças entre os resultados obtidos por simulação e os previstos pelos modelos clássicos. Para a geometria utilizada do lavador, notou-se a presença de regiões de recirculação para as condições estudadas, possivelmente explicando as diferenças entre as simulações e os modelos. Obtiveram-se, também, resultados da distribuição de líquido ao longo do lavador.
Tribology Transactions, 2012
ABSTRACT The stability of oil-in-water (O/W) emulsions used as metalworking fluids is a key facto... more ABSTRACT The stability of oil-in-water (O/W) emulsions used as metalworking fluids is a key factor for the economical and environmental balance of the entire metalworking process because used and broken fluids must be recycled or disposed. In this study, the ability of turbidimetric spectroscopy in the ultraviolet and visible light range to detect metalworking fluids destabilization was evaluated. Destabilization was achieved by adding calcium chloride, thus achieving accelerated aging, which leads to coalescence, creaming, and complete emulsion separation. The stability of the metalworking fluids at 5% volumetric concentration in deionized water was monitored using a spectroscopic turbidimeter composed of an optical probe for in-line measurements. Destabilization was also monitored by measuring the vertical profile of backscattered and transmitted light. The results of this offline measurement system were compared with those from the in-line spectroscopic sensor, indicating that the latter can provide local, real-time information on emulsion destabilization, thus enabling control actions.
Chemical Engineering & Technology, 2010
The aim of this work is the study of batch liquid-liquid extraction of phenol from aqueous soluti... more The aim of this work is the study of batch liquid-liquid extraction of phenol from aqueous solutions in a bench-scale well-mixed reactor. The influence of the ratio of phase volumes, temperature, and rotational speed on phenol removal (0.72-1.1 % w/w) was investigated using methyl isobutyl ketone as an extracting solvent. For this purpose, the ratio of phase volumes were set at 0.1 and 0.2, the temperature at 10, 20, and 30°C, and the rotational speed at 300, 400, and 500 rpm. A physical model based on the material balance of the phases as well as the equation of mass flux between the phases allowed the estimation of the overall coefficient of mass transfer coupled with the superficial area. Moreover, it proved to fit, satisfactorily well, the experimental data of residual phenol concentration in the organic phase versus time under all the conditions investigated.
Chemical engineering transactions, Apr 20, 2011
The aim is to show a methodology to characterize the cooling tower performance, when submitted to... more The aim is to show a methodology to characterize the cooling tower performance, when submitted to diverse operational conditions. The experiments were carried out in a pilot plant and a correlation between the cooling tower performance and the principal process variables (air and water mass flow rates) was obtained. The methodology developed can be applied in industrial cooling towers because the measures are usually available in typical plants. A parametric simulation study was developed to investigate the influence of gas flow rate, liquid flow rate and cooling water height of filling in the thermal demand of a cooling water system. The proposed study and analysis should be useful for performance analysis of real-world cooling water and the Management of Cooling Tower System.
Chemical engineering transactions, Apr 20, 2011
The process for removing carbon dioxide from industrial gases can be achieved by absorption into ... more The process for removing carbon dioxide from industrial gases can be achieved by absorption into aqueous solutions of alkanolamines. Mass transfer parameters in different alkanolamines solutions were investigated in a wetted wall column with a film promoter of thin stainless steel woven wire. The average overall volumetric mass transfer coefficient was measured at 25 ºC, atmospheric pressure. The total gas flow rate at 2.8. 10-4 m 3 /s, with a composition of 10 % CO 2 , was also measured in different liquid flow rates. The tested alkanolamines in the different experiments were monoethanolamine (MEA) and 2-amine-2-methyl-1 propanol (AMP). The absorption experiments were performed in individual alkanolamines aqueous solutions and their respective blends, aiming to combine the favorable features of individual alkanolamines while reducing the unfavorable features. The effective interfacial area of the column, a e , was determinated through the absorption of CO 2 diluted in air with an aqueous solution of NaOH, 2N, for different liquid flow rates. The results indicate that the average overall volumetric coefficients of mass transfer of the MEA and the mixture based on it are higher in relation to AMP. Moreover, this parameter is significantly affected by the behaviour of the film liquid flow rate provided by the film promoter, thus, affecting the efficiency of CO 2 removal.
Chemical Engineering and Processing, Nov 1, 2013
The process for removing carbon dioxide from industrial gases can be achieved by absorption into ... more The process for removing carbon dioxide from industrial gases can be achieved by absorption into aqueous solutions of alkanolamines. Mass transfer parameters in different alkanolamines solutions were investigated in a wetted wall column with a film promoter of thin stainless steel woven wire. The average overall volumetric mass transfer coefficient was measured at 25 ºC, atmospheric pressure. The total gas flow rate at 2.8. 10-4 m 3 /s, with a composition of 10 % CO 2 , was also measured in different liquid flow rates. The tested alkanolamines in the different experiments were monoethanolamine (MEA) and 2-amine-2-methyl-1 propanol (AMP). The absorption experiments were performed in individual alkanolamines aqueous solutions and their respective blends, aiming to combine the favorable features of individual alkanolamines while reducing the unfavorable features. The effective interfacial area of the column, a e , was determinated through the absorption of CO 2 diluted in air with an aqueous solution of NaOH, 2N, for different liquid flow rates. The results indicate that the average overall volumetric coefficients of mass transfer of the MEA and the mixture based on it are higher in relation to AMP. Moreover, this parameter is significantly affected by the behaviour of the film liquid flow rate provided by the film promoter, thus, affecting the efficiency of CO 2 removal.
Esta obra apresenta a disciplina de probabilidades em um status especial entre as demais em um cu... more Esta obra apresenta a disciplina de probabilidades em um status especial entre as demais em um curso de engenharia. Sua posição pode ser compreendida quando contemplamos o desenvolvimento das ciências aplicadas ao longo da história. Todas essas mudanças estão ligadas à mudança de paradigmas que ocorreu na transição entre os séculos 19 e 20, período rico também em convulsões sociais, entre elas a formação de vários estados modernos e várias revoluções. Basta mencionar o da Alemanha, Itália, a Revolução Meiji, a independência de nosso país e de outros, a revolução russa e a Primeira Guerra. Um curso de probabilidades para engenharia marca essa transição histórica e oferece uma visão de mundo diferente, em que se coloca uma ordem no caos.
XVI COBEQ; III CBTERMO:engenharia química & inovação : anais Lorena : EEL-USP/UNICAMP/ABEQ, 2006, 2006
VI COBEQ-IC : programação e resumos, 2005
Computer-aided chemical engineering, 2023
Industrial & Engineering Chemistry Research, Oct 7, 2022
Fluids, Feb 23, 2017
Working fluids possess several applications in manufacturing processes, for instance lubricants i... more Working fluids possess several applications in manufacturing processes, for instance lubricants in metals machining. Typical metal working fluids are formulated as oil-in-water emulsions. The maintenance of the physical stability of the working fluid during operation is a key factor for the sustainability of the relevant process. Therefore, continuous control of the working fluids stability and performance during machine operation is an essential tool for maintenance of the process performance. Turbidity measurement (TM) is a process technique for emulsion stability and quality assessment, where light transmission and absorption of an emulsion system is analyzed. However, for in-process measurement and fluid quality detection during the machine operation by TM, it is necessary to implement a transmission inline sensor into the working fluid flow line. The continuous flow measurement may cause problems for long-term sensor operation regarding, e.g., biofouling of the sensor optical glasses or erroneous measurements due to emulsion droplets segregation effects. In the present investigation, computational fluid dynamic (CFD) simulations have been adapted to obtain the emulsion flow conditions within a typical TM sensor probe, thereby allowing an assessment of the adhesion probability of microorganisms as well as droplet segregation effects. The simulation results indicate some temporal changes of the dispersed phase concentration in the detected emulsion flow. Due to droplet segregation in the emulsion, the flow velocity needs to exceed a certain value for reliable operation. It is shown here that in this flow regime microbiological attachments on the probe surfaces may be sufficiently avoided. A minimum critical flow velocity is derived to avoid biomolecule adhesion and thus durable operation of the sensor.
International Conference on Liquid Atomization and Spray Systems (ICLASS), 2021
Sprays of molten metal are known to exhibit rich spatio-temporal dynamics, such as a pulsating me... more Sprays of molten metal are known to exhibit rich spatio-temporal dynamics, such as a pulsating metal mass flux, or a precession motion of the melt plume. Powerful tools for their investigation are high-speed recordings combined with digital image processing. In this work, we present a method to generate spatio-temporal diagrams from the recordings. These diagrams are ideally suited to quantify spray fluctuations in space and time. Experiments were conducted in an annular close-coupled atomizer using a copper alloy (CuSn6) as base material with varying atomization gas pressures ([0.8, 1.2, 1.6, 2.0] MPa) and temperatures ([293, 423, 523] K). The region of the primary atomization was monitored with a high-speed camera recording 21,800 frames per second. At the parameters investigated we observe an oscillation of the spray boundaries below 100 Hz indicating a slow precession motion. The analysis of the statistically steady spray shape surprisingly reveals a breakdown of the axial symmetry at large gas pressures, whose origin is currently unknown.
SSRN Electronic Journal, 2019
This work aimed to study the chemical desorption process of CO2 in an aqueous solution of 2-amino... more This work aimed to study the chemical desorption process of CO2 in an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) carbonated blend. The desorption process was carried out on a wetted wall column with a 0.5 m long film promoter (stainless steel 28 mesh with a known surface area) and 2.2 cm diameter. The process was online monitored by infrared spectroscopy integrated with a PLS model, which allowed the quantification in the liquid phase of free AMP and PZ, PZ mono-and dicarbamate, bicarbonate and total CO2 absorbed in all its chemical forms. The model had a drawback predicting PZ at low concentrations. The desorption was measured at atmospheric pressure (0.93 atm) and at temperatures of 50, 60 and 70 °C and blends of 30/0, 25/5, 20/10 and 0/15 wt% AMP/wt% PZ respectively. A total of 16 experiments were carried out. The process flowsheet is shown at Figure 1. A solution of 500 g was prepared and carbonated to saturation. It was pre-heated to the experiment temperature and loaded through the top of the column to wet all the the film promoter. By a peristaltic pump the solution with constant flow rate of 3.5 mL•s-1 went to the top of the column, where the liquid was distributed through all the perimeter of the promoter by a distributor. About 10 % of the flow rate past through the spectrometer where the solution was simultaneously quantified. The temperature of column tube-side liquid film was maintained by a thermostatic water heat system on the shell-side. Atmospheric air at constant flow rate of 100 mL•s-1 was preheated using water vapor generated in a boiler and then was bubbled in a heated water flask to saturate it completely at the temperature of the system. Then was bubbled in the solution and fed to the bottom of the column. The CO 2 desorption experiments work in as a quasi-stationary process. The rate of CO 2 desorbed was calculated by the mass balance of CO 2 in the liquid phase and the desorption flux is determined by the ratio to mass transfer area. The CO2 concentration on the inlet gas-bottom of the column-was assumed zero and the CO2 partial pressure on the outlet top of the column was found as CO2 desorbed divided by the gas flowing through the column. The overall mass transfer coefficient (KG) was calculated by the ratio of desorption flux and the log mean CO2 partial pressure driving force. The liquid film mass transfer coefficient (kL) was found using the series resistance relationship and a correlation was used to find the gas film mass transfer (kg). The kL decreased with higher values of CO2 loadings (α). The PZ solutions shown the lowest kL values, followed by the AMP solutions, and the blend showed the highest values of kL, increasing with PZ concentration in the mixture. The temperature had no significant influence on the values of kL. Figure 2 shows kL values at 50 ºC for different compositions.
Wear, 2020
This paper reports and discusses the results of an experimental investigation on hydraulic transp... more This paper reports and discusses the results of an experimental investigation on hydraulic transportation of iron ore concentrate and its effect on slurry wear, pure erosion and pure corrosion of a carbon steel pipe. For this, a specially designed test-loop was built to simulate long distance iron ore transportation, allowing also to determine pure erosion effects by means of a specially designed cathodic protection system. Pure corrosion damage was evaluated by linear polarization measurements in filtered ore concentrate, i.e., in the absence of particles. The results revealed that pure erosion and pure corrosion effects were much lower than the measured wear, evaluated as pipe thickness loss, indicating an important synergism between erosion and corrosion. Wear damage results in microcraters aligned in the flow direction, which merge with each other likely due to enhanced electrochemical activity fed by the erosion process. Evaluation of the effect of the pumping time on the ore concentrate characteristics revealed that particles sizes decreased while the sphericity factor increased leading to lower wear rates. Finally, a mechanism explaining the pipeline wear associating erosion, corrosion and the material microstructure as well as a methodology to forecast the pipelines thickness loss as a function of the ore concentrate travelling distance were also proposed.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2018
A study on process alternatives for reducing steam consumption was carried out in a multistage ev... more A study on process alternatives for reducing steam consumption was carried out in a multistage evaporation system of a chlorine-alkali industrial complex. A phenomenological model was developed, based on the mass and energy balances and on gas-liquid equilibrium correlations for the ternary mixture of caustic soda, sodium chloride and water. The design specifications of the plant were adopted as a reference to validate the mathematical model, which comprises 153 nonlinear equations. Different process conditions were simulated by taking into account the most important process variables and their effect on steam consumption. Differently from previously published studies, in which the conservation laws are mainly focused on the heat exchangers and their optimization, the present study considers the whole multistage evaporation unit. The model also enabled to evaluate the effect of changes in the plant configuration, either by considering a side product stream at a specified concentration, designated to another production unit in the industrial complex, or by including mechanical vapor recompression, which has proven to be a better solution to reduce steam consumption from the energy and exergy points of view. Results indicate an expressive decrease in steam consumption to around 1% of the original configuration. Moreover, from the exergy perspective, if the power generation is considered, the MVR is a better choice from the energy and exergy point of view. Keywords Exergy analysis Á Caustic soda production Á Evaporation process Á Mass and energy balances List of symbols b Specific exergy (kJ/kg) B Exergy flow rate (kW) This paper is an extended and revised version of a similar work presented in the
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Lavadores Venturi são utilizados industrialmente para o controle da emissão de poluentes. Simulou... more Lavadores Venturi são utilizados industrialmente para o controle da emissão de poluentes. Simulou-se a variação de vazões de líquido e gás em lavador Venturi industrial utilizando técnicas de CFD (Fluidodinâmica Computacional). Com o auxílio do software ANSYS CFX 15.0, simulou-se o escoamento bifásico, utilizando o modelo de fluidos interpenetrantes (abordagem Euler-Euler) e o modelo de turbulência k-ε padrão. Observou-se que a variação de pressão ao longo do Venturi calculada é, de forma geral, muito próxima da prevista pelos modelos clássicos de Boll (1973) e Viswanathan (1985). No entanto, para algumas condições de vazão de gás e líquido, observaram-se diferenças entre os resultados obtidos por simulação e os previstos pelos modelos clássicos. Para a geometria utilizada do lavador, notou-se a presença de regiões de recirculação para as condições estudadas, possivelmente explicando as diferenças entre as simulações e os modelos. Obtiveram-se, também, resultados da distribuição de líquido ao longo do lavador.
Tribology Transactions, 2012
ABSTRACT The stability of oil-in-water (O/W) emulsions used as metalworking fluids is a key facto... more ABSTRACT The stability of oil-in-water (O/W) emulsions used as metalworking fluids is a key factor for the economical and environmental balance of the entire metalworking process because used and broken fluids must be recycled or disposed. In this study, the ability of turbidimetric spectroscopy in the ultraviolet and visible light range to detect metalworking fluids destabilization was evaluated. Destabilization was achieved by adding calcium chloride, thus achieving accelerated aging, which leads to coalescence, creaming, and complete emulsion separation. The stability of the metalworking fluids at 5% volumetric concentration in deionized water was monitored using a spectroscopic turbidimeter composed of an optical probe for in-line measurements. Destabilization was also monitored by measuring the vertical profile of backscattered and transmitted light. The results of this offline measurement system were compared with those from the in-line spectroscopic sensor, indicating that the latter can provide local, real-time information on emulsion destabilization, thus enabling control actions.
Chemical Engineering & Technology, 2010
The aim of this work is the study of batch liquid-liquid extraction of phenol from aqueous soluti... more The aim of this work is the study of batch liquid-liquid extraction of phenol from aqueous solutions in a bench-scale well-mixed reactor. The influence of the ratio of phase volumes, temperature, and rotational speed on phenol removal (0.72-1.1 % w/w) was investigated using methyl isobutyl ketone as an extracting solvent. For this purpose, the ratio of phase volumes were set at 0.1 and 0.2, the temperature at 10, 20, and 30°C, and the rotational speed at 300, 400, and 500 rpm. A physical model based on the material balance of the phases as well as the equation of mass flux between the phases allowed the estimation of the overall coefficient of mass transfer coupled with the superficial area. Moreover, it proved to fit, satisfactorily well, the experimental data of residual phenol concentration in the organic phase versus time under all the conditions investigated.