Heavy metal pollution is a silent killer and has become a pervasive issue in various regions worl... more Heavy metal pollution is a silent killer and has become a pervasive issue in various regions worldwide, particularly within developing nations such as Nigeria. This study undertook a thorough examination of 120 scholarly articles published from 2000 to 2019, aimed at evaluating the prevalence of heavy metal pollution in soils, aquatic environments, and food sources including crops, meat, and dairy products. Methodologies employed for sample collection and metal quantification were critically assessed, alongside an extensive discussion on the concentrations, sources, and levels of contamination observed. The investigation revealed elevated concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), cobalt (Co), chromium (Cr), iron (Fe), and arsenic (As) across all examined locales, with average metal concentrations surpassing World Health Organization/Food and Agriculture Organization (WHO/FAO) guidelines for soil. Furthermore, higher metal concentrations were detected in surface and well waters, whereas borehole groundwaters were relatively pollution-free. Analysis of food crops, meat, and milk demonstrated metal concentrations exceeding WHO/FAO standards across all urban areas studied. Contrary to expectations of lithogenic toxicity, the primary sources of contamination were identified as anthropogenic, stemming from dumpsites, landfill sites, mining operations, runoff and seepage from automotive repair workshops, petroleum hydrocarbon spills, and effluents from industrial plants. The geo-accumulation index (Igeo) analysis revealed significant soil contamination with Fe and Cd, classifed under extremely serious and moderate contamination levels, respectively. This comprehensive review highlights the necessity for viable and clear policy interventions to mitigate heavy metal pollution and advocates for the rigorous monitoring and control of industrial activities.
Journal of Petroleum Science and Engineering, 2021
Abstract The maintenance of wellbore stability remains one of the major sources of Non-Productive... more Abstract The maintenance of wellbore stability remains one of the major sources of Non-Productive Time in the oil industry. During drilling process, the drill string vibration cyclic loads which are applied on the wellbore progressively affect the initial parameters of the fractured formation (such as its length and width), finally resulting into wellbore instability. In this research, a three-dimensional poro elasto plastic finite element model was built using a non-linear finite element software ABAQUS purposely to investigate the effect of drill string vibration cyclic loads on the wellbore natural fracture growth. The main conclusions exhibited that the dependency of the fracture width profiles with the time followed an oscillating comportment analogous to the vibration cyclic loads profiles. For distinct cyclic load magnitudes and constant number of cyclic loads, the biggest percentage augmentation of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the aperture of the fracture increased with the length of the fracture in the region neighboring the wellbore while it globally declined when going farther aside the wellbore. But for constant magnitude of cyclic load and distinct cyclic loads number, the highest rate of fracture aperture augmentation after incorporation of cyclic loads was moderately smaller representing 63.12% while the sinusoidal period of the fracture aperture grew with the number of cyclic loads number. The alternate studies demonstrated that the vibration cyclic loads were approximately unrelated to the fracture length development and the bottom hole pressure evolution. However, the fracture aperture and the loss circulation rate were significantly influenced by the vibration and the biggest percentage augmentation of the loss circulation rate after implementation of cyclic loads was 14.3%. This study broadens the understanding of the coupling between the drill string vibration cyclic loads and the wellbore natural fracture rock development which is a thematic that has been seldom examined in the literature.
Abstract Effects of some important structural parameters, i.e. slat pitch, and layout position, o... more Abstract Effects of some important structural parameters, i.e. slat pitch, and layout position, on dynamic forces acting on the baffles were examined in the fluidized bed of FCC particles operating under different superficial gas velocities. The experimental baffles were made of multiple inclined slats. We found that the forces acting on the baffles decreased significantly with reducing pitch between the slats. For the baffles with a small slat pitch, the forces acting on the baffles increased slightly and then decreased with increasing superficial gas velocity, which is very different from the measured results of a single slat or tube immersed in fluidized beds. The different results are greatly related to the appearance of the “gas cushion” beneath the baffles, whose height increases with increasing superficial gas velocity. On the other hand, a region with stronger particle circulation induced by the inclined slat array was observed in the experiments. The slat near the wall and located below the region of downward-flowing particles was found to be subjected to the severest forces. Therefore, the slats located in similar locations of industrial baffles are suggested to be reinforced to increase their structural strength.
Wellbore instability is one of the most serious issues faced in the drilling process. During dril... more Wellbore instability is one of the most serious issues faced in the drilling process. During drilling operations, the cyclic loads applied on the fractured formation progressively modify the initial parameters (i.e., length and width) of the fractured formation, thus resulting into undesirable wellbore instability. In this paper, using a nonlinear finite element software (ABAQUS) as the numerical simulator, a poro-elasto-plastic model has been established which aimed at analyzing the influence of drill string vibration cyclic loads on the development of the wellbore natural fracture. The numerical results showed that the fracture width as a function of time profiles followed a sinusoidal behavior similar to the drill string vibration cyclic load profiles. For different cyclic load magnitudes with constant number of cyclic loads, the highest percentage increase of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the fracture width increased with the fra...
Deep understanding of the complex relationship between the complex hydrodynamics and reactor perf... more Deep understanding of the complex relationship between the complex hydrodynamics and reactor performance in a reactive gas-fluidized bed is crucial to optimization of engineering design and industrial operation. In this work, multiphase particle-in-cell (MP-PIC) simulations coupled with reaction kinetics models are conducted to investigate the effect of gas distribution on reactor performance. A batch fluidized bed reactor with different distributors for regenerating spent FCC catalyst is simulated under different superficial gas velocities. In all simulation cases, the air flowrate and the spent catalyst inventory are kept constant. The results show an indiscernible effect of superficial gas velocity, but the induced-maldistribution conditions generally deteriorate the reactor performance. In addition to wall-slug formation, solids holdup, and slip velocities also decrease significantly in the plugged-gas distribution cases. Strong linear relationship between hydrodynamics and reactor performance are established. Present study sheds light on the importance of uniform gas distribution in industrial fluidized bed reactors.
Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator pla... more Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator plays a critical role in optimizing the overall profitability by efficiently restoring the catalyst activity and enhancing the heat balance in the riser reactor. Improvement in the device metallurgy and process operations have enabled industrial regenerators to operate at high temperatures with a better coke burning rate and longer operating cycle. Today, the carbon content of regenerated catalyst has drastically reduced to less than 0.1 wt.%. However, the unit is still plagued with operational complexities and insufficient understanding of the underlying dynamic, multiscale intricacies. Recent process-intensification strategies provide insights into regenerator performance improvement potentials. In this review, the importance of the uniform distribution of spent catalysts through structural modification and operational manipulations of the catalyst distributor is discussed. The knowledge ...
Background: Food safety is a major public concern worldwide. During the last decades, the increas... more Background: Food safety is a major public concern worldwide. During the last decades, the increasing demand for food safety has stimulated research regarding the risk associated with consumption of foodstuffs contaminated by pesticides, heavy metals and or toxins. Materials and Methods: In this study, selected heavy metals (Cd, Cr, Cu, Pb and Zn) in Green peas sold at Gwagwalada and Wuse markets in Abuja have been investigated. The samples were wet digested and the metals were analysed using Atomic Absoprtion Spectrophotometer (AAS). Results: The mean metal levels were found to be 0.75, 17.38, 0.75, 0.13, B.D.L, 34.50 μg/g for Cd, Cr, Cu Pb and Zn respectively. Zn was the highest metal found and Pb was below detection limit. The metal levels found in the study were compared with regional or international standards to determine whether these levels are within acceptable limits in foods. Conclusion: Notably, only Cd level was above the safe limits when compared with the National Agenc...
Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effecti... more Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effective measures to improve the regeneration performance of a fluid catalytic cracking (FCC) unit. In this study, the effects of the spent catalyst distribution and horizontal baffle on the regeneration performance of an industrial coaxial compact FCC regenerator is simulated using an Eulerian-Lagrangian multi-phase particle in cell (MP-PIC) method with coupled hydrodynamic and coke-burning kinetics models. The coke-burning kinetics model developed by Arbel et al. (Ind Eng Chem Res, 1995, 34(4): 1228–1243) is used in the simulation. The MP-PIC simulations successfully predicted agreeable temperatures in the industrial regenerator. Serious afterburning in the freeboard was also successfully predicted. The effectiveness of the two intensification measures in enhancing the performance of an industrial FCC regenerator were proved, as indicated by the restrained afterburning in the freeboard, the ...
Abstract Improving distribution uniformity of spent catalyst and adding horizontal baffles are tw... more Abstract Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effective measures to improve the regeneration performance of a fluid catalytic cracking (FCC) unit. In this study, an industrial coaxial compact FCC regenerator is simulated using a Eulerian- Lagrangian multi-phase particle in cell (MP-PIC) method. By using the energy-minimization multi-scale (EMMS) drag model based on turbulent flow regime, the MP-PIC simulation predicts the typical solids fraction profile which is in good agreement with industrial data. The Crosser grid (a typical horizontal baffle) is successfully constructed with the help of “virtual baffles” in simulation. The simulation results show that, after adding Crosser grid (a new horizontal fluidized bed baffle by our group), the bed height increases slightly, the lateral mal-distribution index of solids decreases and the descending flux of spent catalysts decreases significantly. The distribution uniformity of spent catalyst distribution along the bed cross section is more uniform when spent catalyst particles are distributed more uniformly. The presence of gas cushion beneath the Crosser grid allows it to act as a pseudo gas distributor, eliminating gas channeling and decreasing zones of low fluidization quality. The rising bubbles are absorbed by the gas cushion and new small bubbles are generated above the Crosser grid, thereby strengthening the gas–solid contact. The guiding vanes of Crosser grid accelerate the lateral movement of particles. The Crosser grid also proves its stronger suppression on the axial back-mixing of solids.
Heavy metal pollution is a silent killer and has become a pervasive issue in various regions worl... more Heavy metal pollution is a silent killer and has become a pervasive issue in various regions worldwide, particularly within developing nations such as Nigeria. This study undertook a thorough examination of 120 scholarly articles published from 2000 to 2019, aimed at evaluating the prevalence of heavy metal pollution in soils, aquatic environments, and food sources including crops, meat, and dairy products. Methodologies employed for sample collection and metal quantification were critically assessed, alongside an extensive discussion on the concentrations, sources, and levels of contamination observed. The investigation revealed elevated concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), cobalt (Co), chromium (Cr), iron (Fe), and arsenic (As) across all examined locales, with average metal concentrations surpassing World Health Organization/Food and Agriculture Organization (WHO/FAO) guidelines for soil. Furthermore, higher metal concentrations were detected in surface and well waters, whereas borehole groundwaters were relatively pollution-free. Analysis of food crops, meat, and milk demonstrated metal concentrations exceeding WHO/FAO standards across all urban areas studied. Contrary to expectations of lithogenic toxicity, the primary sources of contamination were identified as anthropogenic, stemming from dumpsites, landfill sites, mining operations, runoff and seepage from automotive repair workshops, petroleum hydrocarbon spills, and effluents from industrial plants. The geo-accumulation index (Igeo) analysis revealed significant soil contamination with Fe and Cd, classifed under extremely serious and moderate contamination levels, respectively. This comprehensive review highlights the necessity for viable and clear policy interventions to mitigate heavy metal pollution and advocates for the rigorous monitoring and control of industrial activities.
Journal of Petroleum Science and Engineering, 2021
Abstract The maintenance of wellbore stability remains one of the major sources of Non-Productive... more Abstract The maintenance of wellbore stability remains one of the major sources of Non-Productive Time in the oil industry. During drilling process, the drill string vibration cyclic loads which are applied on the wellbore progressively affect the initial parameters of the fractured formation (such as its length and width), finally resulting into wellbore instability. In this research, a three-dimensional poro elasto plastic finite element model was built using a non-linear finite element software ABAQUS purposely to investigate the effect of drill string vibration cyclic loads on the wellbore natural fracture growth. The main conclusions exhibited that the dependency of the fracture width profiles with the time followed an oscillating comportment analogous to the vibration cyclic loads profiles. For distinct cyclic load magnitudes and constant number of cyclic loads, the biggest percentage augmentation of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the aperture of the fracture increased with the length of the fracture in the region neighboring the wellbore while it globally declined when going farther aside the wellbore. But for constant magnitude of cyclic load and distinct cyclic loads number, the highest rate of fracture aperture augmentation after incorporation of cyclic loads was moderately smaller representing 63.12% while the sinusoidal period of the fracture aperture grew with the number of cyclic loads number. The alternate studies demonstrated that the vibration cyclic loads were approximately unrelated to the fracture length development and the bottom hole pressure evolution. However, the fracture aperture and the loss circulation rate were significantly influenced by the vibration and the biggest percentage augmentation of the loss circulation rate after implementation of cyclic loads was 14.3%. This study broadens the understanding of the coupling between the drill string vibration cyclic loads and the wellbore natural fracture rock development which is a thematic that has been seldom examined in the literature.
Abstract Effects of some important structural parameters, i.e. slat pitch, and layout position, o... more Abstract Effects of some important structural parameters, i.e. slat pitch, and layout position, on dynamic forces acting on the baffles were examined in the fluidized bed of FCC particles operating under different superficial gas velocities. The experimental baffles were made of multiple inclined slats. We found that the forces acting on the baffles decreased significantly with reducing pitch between the slats. For the baffles with a small slat pitch, the forces acting on the baffles increased slightly and then decreased with increasing superficial gas velocity, which is very different from the measured results of a single slat or tube immersed in fluidized beds. The different results are greatly related to the appearance of the “gas cushion” beneath the baffles, whose height increases with increasing superficial gas velocity. On the other hand, a region with stronger particle circulation induced by the inclined slat array was observed in the experiments. The slat near the wall and located below the region of downward-flowing particles was found to be subjected to the severest forces. Therefore, the slats located in similar locations of industrial baffles are suggested to be reinforced to increase their structural strength.
Wellbore instability is one of the most serious issues faced in the drilling process. During dril... more Wellbore instability is one of the most serious issues faced in the drilling process. During drilling operations, the cyclic loads applied on the fractured formation progressively modify the initial parameters (i.e., length and width) of the fractured formation, thus resulting into undesirable wellbore instability. In this paper, using a nonlinear finite element software (ABAQUS) as the numerical simulator, a poro-elasto-plastic model has been established which aimed at analyzing the influence of drill string vibration cyclic loads on the development of the wellbore natural fracture. The numerical results showed that the fracture width as a function of time profiles followed a sinusoidal behavior similar to the drill string vibration cyclic load profiles. For different cyclic load magnitudes with constant number of cyclic loads, the highest percentage increase of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the fracture width increased with the fra...
Deep understanding of the complex relationship between the complex hydrodynamics and reactor perf... more Deep understanding of the complex relationship between the complex hydrodynamics and reactor performance in a reactive gas-fluidized bed is crucial to optimization of engineering design and industrial operation. In this work, multiphase particle-in-cell (MP-PIC) simulations coupled with reaction kinetics models are conducted to investigate the effect of gas distribution on reactor performance. A batch fluidized bed reactor with different distributors for regenerating spent FCC catalyst is simulated under different superficial gas velocities. In all simulation cases, the air flowrate and the spent catalyst inventory are kept constant. The results show an indiscernible effect of superficial gas velocity, but the induced-maldistribution conditions generally deteriorate the reactor performance. In addition to wall-slug formation, solids holdup, and slip velocities also decrease significantly in the plugged-gas distribution cases. Strong linear relationship between hydrodynamics and reactor performance are established. Present study sheds light on the importance of uniform gas distribution in industrial fluidized bed reactors.
Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator pla... more Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator plays a critical role in optimizing the overall profitability by efficiently restoring the catalyst activity and enhancing the heat balance in the riser reactor. Improvement in the device metallurgy and process operations have enabled industrial regenerators to operate at high temperatures with a better coke burning rate and longer operating cycle. Today, the carbon content of regenerated catalyst has drastically reduced to less than 0.1 wt.%. However, the unit is still plagued with operational complexities and insufficient understanding of the underlying dynamic, multiscale intricacies. Recent process-intensification strategies provide insights into regenerator performance improvement potentials. In this review, the importance of the uniform distribution of spent catalysts through structural modification and operational manipulations of the catalyst distributor is discussed. The knowledge ...
Background: Food safety is a major public concern worldwide. During the last decades, the increas... more Background: Food safety is a major public concern worldwide. During the last decades, the increasing demand for food safety has stimulated research regarding the risk associated with consumption of foodstuffs contaminated by pesticides, heavy metals and or toxins. Materials and Methods: In this study, selected heavy metals (Cd, Cr, Cu, Pb and Zn) in Green peas sold at Gwagwalada and Wuse markets in Abuja have been investigated. The samples were wet digested and the metals were analysed using Atomic Absoprtion Spectrophotometer (AAS). Results: The mean metal levels were found to be 0.75, 17.38, 0.75, 0.13, B.D.L, 34.50 μg/g for Cd, Cr, Cu Pb and Zn respectively. Zn was the highest metal found and Pb was below detection limit. The metal levels found in the study were compared with regional or international standards to determine whether these levels are within acceptable limits in foods. Conclusion: Notably, only Cd level was above the safe limits when compared with the National Agenc...
Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effecti... more Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effective measures to improve the regeneration performance of a fluid catalytic cracking (FCC) unit. In this study, the effects of the spent catalyst distribution and horizontal baffle on the regeneration performance of an industrial coaxial compact FCC regenerator is simulated using an Eulerian-Lagrangian multi-phase particle in cell (MP-PIC) method with coupled hydrodynamic and coke-burning kinetics models. The coke-burning kinetics model developed by Arbel et al. (Ind Eng Chem Res, 1995, 34(4): 1228–1243) is used in the simulation. The MP-PIC simulations successfully predicted agreeable temperatures in the industrial regenerator. Serious afterburning in the freeboard was also successfully predicted. The effectiveness of the two intensification measures in enhancing the performance of an industrial FCC regenerator were proved, as indicated by the restrained afterburning in the freeboard, the ...
Abstract Improving distribution uniformity of spent catalyst and adding horizontal baffles are tw... more Abstract Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effective measures to improve the regeneration performance of a fluid catalytic cracking (FCC) unit. In this study, an industrial coaxial compact FCC regenerator is simulated using a Eulerian- Lagrangian multi-phase particle in cell (MP-PIC) method. By using the energy-minimization multi-scale (EMMS) drag model based on turbulent flow regime, the MP-PIC simulation predicts the typical solids fraction profile which is in good agreement with industrial data. The Crosser grid (a typical horizontal baffle) is successfully constructed with the help of “virtual baffles” in simulation. The simulation results show that, after adding Crosser grid (a new horizontal fluidized bed baffle by our group), the bed height increases slightly, the lateral mal-distribution index of solids decreases and the descending flux of spent catalysts decreases significantly. The distribution uniformity of spent catalyst distribution along the bed cross section is more uniform when spent catalyst particles are distributed more uniformly. The presence of gas cushion beneath the Crosser grid allows it to act as a pseudo gas distributor, eliminating gas channeling and decreasing zones of low fluidization quality. The rising bubbles are absorbed by the gas cushion and new small bubbles are generated above the Crosser grid, thereby strengthening the gas–solid contact. The guiding vanes of Crosser grid accelerate the lateral movement of particles. The Crosser grid also proves its stronger suppression on the axial back-mixing of solids.
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Papers by Adefarati Ayo
Health Organization/Food and Agriculture Organization (WHO/FAO) guidelines for soil. Furthermore, higher metal concentrations were detected in surface and well waters, whereas borehole groundwaters were relatively pollution-free. Analysis of food crops, meat, and milk demonstrated metal concentrations exceeding WHO/FAO standards across all urban areas studied. Contrary to expectations of lithogenic
toxicity, the primary sources of contamination were identified as anthropogenic, stemming from dumpsites, landfill sites, mining operations, runoff and seepage from automotive repair workshops, petroleum hydrocarbon spills, and effluents from industrial plants. The geo-accumulation index (Igeo) analysis revealed significant soil contamination with Fe and Cd, classifed under extremely serious and moderate
contamination levels, respectively. This comprehensive review highlights the necessity for viable and clear policy interventions to mitigate heavy metal pollution and advocates for the rigorous monitoring and control of industrial activities.
Health Organization/Food and Agriculture Organization (WHO/FAO) guidelines for soil. Furthermore, higher metal concentrations were detected in surface and well waters, whereas borehole groundwaters were relatively pollution-free. Analysis of food crops, meat, and milk demonstrated metal concentrations exceeding WHO/FAO standards across all urban areas studied. Contrary to expectations of lithogenic
toxicity, the primary sources of contamination were identified as anthropogenic, stemming from dumpsites, landfill sites, mining operations, runoff and seepage from automotive repair workshops, petroleum hydrocarbon spills, and effluents from industrial plants. The geo-accumulation index (Igeo) analysis revealed significant soil contamination with Fe and Cd, classifed under extremely serious and moderate
contamination levels, respectively. This comprehensive review highlights the necessity for viable and clear policy interventions to mitigate heavy metal pollution and advocates for the rigorous monitoring and control of industrial activities.