Dépouillements

Diffusional effects in nickel oxide reduction kinetics / Peter Erri in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 4-6 Titre : Diffusional effects in nickel oxide reduction kinetics Type de document : texte imprimé Auteurs : Peter Erri, Éditeur scientifique ; Arvind Varma, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 4-6 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nickel oxide Industrial catalyst Résumé : Nickel is widely used as an industrial catalyst and has recently been investigated as an oxygen carrier in chemical looping combustion (CLC), which is a novel approach for power generation that offers inherent CO2 capture. However, prior studies have reported a wide range of activation energy values for nickel formation from the reduction of NiO by hydrogen. In the present work, this reaction was investigated using the Friedman isoconversional method for a series of thermogravimetric curves, which were obtained at varying heating rates. The intrinsic activation energy for the reduction of NiO was observed to be in the range of 91.8−94.5 kJ/mol, whereas values of 42.6 kJ/mol and ∼0 kJ/mol were found at intermediate and high heating rates, respectively, which correspond to intermediate and high temperatures. This demonstrates the presence of internal and external mass-transfer limitations during the reaction, and it provides a likely explanation for the varying activation energy values reported in prior work. Therefore, these findings emphasize the importance of assessing diffusional effects in the determination of reaction kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071588m [article] Diffusional effects in nickel oxide reduction kinetics [texte imprimé] / Peter Erri, Éditeur scientifique ; Arvind Varma, Éditeur scientifique . - 2009 . - p. 4-6. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 4-6 Mots-clés : Nickel oxide Industrial catalyst Résumé : Nickel is widely used as an industrial catalyst and has recently been investigated as an oxygen carrier in chemical looping combustion (CLC), which is a novel approach for power generation that offers inherent CO2 capture. However, prior studies have reported a wide range of activation energy values for nickel formation from the reduction of NiO by hydrogen. In the present work, this reaction was investigated using the Friedman isoconversional method for a series of thermogravimetric curves, which were obtained at varying heating rates. The intrinsic activation energy for the reduction of NiO was observed to be in the range of 91.8−94.5 kJ/mol, whereas values of 42.6 kJ/mol and ∼0 kJ/mol were found at intermediate and high heating rates, respectively, which correspond to intermediate and high temperatures. This demonstrates the presence of internal and external mass-transfer limitations during the reaction, and it provides a likely explanation for the varying activation energy values reported in prior work. Therefore, these findings emphasize the importance of assessing diffusional effects in the determination of reaction kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071588m

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Influence of gas flow rate on liquid distribution in trickle-beds using perforated plates as liquid distributors / Juan-David Llamas in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 7-11 Titre : Influence of gas flow rate on liquid distribution in trickle-beds using perforated plates as liquid distributors Type de document : texte imprimé Auteurs : Juan-David Llamas, Éditeur scientifique ; François Lesage, Éditeur scientifique ; Gabriel Wild, Auteur Année de publication : 2009 Article en page(s) : p. 7-11 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas flow rate liquid distribution Résumé : Two wire mesh tomography devices and a liquid collector were used to study the influence of the gas flow rate on liquid distribution when fluids distribution on top of the reactor is ensured by a perforated plate. In opposition to most of the studies realized by other authors, conditions in which the gas has a negative impact in liquid distribution were evidenced. Indeed, the obtained results show that the influence of gas flow rate depends on the quality of the initial distribution, as the gas forces the liquid to “respect” the distribution imposed at the top of the reactor. Finally, a comparison between the two measuring techniques shows the limitations of the liquid collector and the improper conclusions to which its use could lead. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001155 [article] Influence of gas flow rate on liquid distribution in trickle-beds using perforated plates as liquid distributors [texte imprimé] / Juan-David Llamas, Éditeur scientifique ; François Lesage, Éditeur scientifique ; Gabriel Wild, Auteur . - 2009 . - p. 7-11. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 7-11 Mots-clés : Gas flow rate liquid distribution Résumé : Two wire mesh tomography devices and a liquid collector were used to study the influence of the gas flow rate on liquid distribution when fluids distribution on top of the reactor is ensured by a perforated plate. In opposition to most of the studies realized by other authors, conditions in which the gas has a negative impact in liquid distribution were evidenced. Indeed, the obtained results show that the influence of gas flow rate depends on the quality of the initial distribution, as the gas forces the liquid to “respect” the distribution imposed at the top of the reactor. Finally, a comparison between the two measuring techniques shows the limitations of the liquid collector and the improper conclusions to which its use could lead. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001155

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Understanding riser and downer based fluid catalytic cracking processes by a comprehensive two-dimensional reactor model / Changning Wu in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 12-26 Titre : Understanding riser and downer based fluid catalytic cracking processes by a comprehensive two-dimensional reactor model Type de document : texte imprimé Auteurs : Changning Wu, Éditeur scientifique ; Yi Cheng, Éditeur scientifique ; Yong Jin, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 12-26 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Two-dimensional reactor Fluid catalytic cracking Résumé : A two-dimensional reactor model incorporating hydrodynamics, mass balance, energy balance, and a 4-lump/14-lump kinetic model was established to simulate the riser and downer based fluid catalytic cracking (FCC) processes. The kinetic parameters of the 4-lump kinetic model were re-evaluated from the originally published experimental data for a more reliable description of the FCC process. The 14-lump kinetic model based on a molecular description of cracking and hydrogen transfer reactions was to include more details about the feedstock composition, reaction mechanisms, and the products distribution for a better understanding on the reactor performance for FCC process. This comprehensive model captured the key characteristics of the gas−solid reacting flows in the riser and downer, i.e., the uniformity of flow structures, the distinct backmixing behavior in the riser and downer, and the momentum and energy balances during the complex FCC reactions. The model predictions were first validated against industrial data from several literature sources and found to agree with each other reasonably well. Then, the simulations were carried out to fully understand the different reactor performances of riser and downer in the application of FCC refining processes. It can be concluded that the downer benefits from its advantages of the plug-flow nature and uniform flow structures, tending to have more products in the middle distillates, e.g., gasoline and light olefins, especially under high-severity operations. Better control of the reaction extent for increased selectivity to desired intermediate products would allow the use of downer reactors for the larger-scale practical applications in the FCC process, together with the valuable byproduction of light olefins. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800168x [article] Understanding riser and downer based fluid catalytic cracking processes by a comprehensive two-dimensional reactor model [texte imprimé] / Changning Wu, Éditeur scientifique ; Yi Cheng, Éditeur scientifique ; Yong Jin, Éditeur scientifique . - 2009 . - p. 12-26. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 12-26 Mots-clés : Two-dimensional reactor Fluid catalytic cracking Résumé : A two-dimensional reactor model incorporating hydrodynamics, mass balance, energy balance, and a 4-lump/14-lump kinetic model was established to simulate the riser and downer based fluid catalytic cracking (FCC) processes. The kinetic parameters of the 4-lump kinetic model were re-evaluated from the originally published experimental data for a more reliable description of the FCC process. The 14-lump kinetic model based on a molecular description of cracking and hydrogen transfer reactions was to include more details about the feedstock composition, reaction mechanisms, and the products distribution for a better understanding on the reactor performance for FCC process. This comprehensive model captured the key characteristics of the gas−solid reacting flows in the riser and downer, i.e., the uniformity of flow structures, the distinct backmixing behavior in the riser and downer, and the momentum and energy balances during the complex FCC reactions. The model predictions were first validated against industrial data from several literature sources and found to agree with each other reasonably well. Then, the simulations were carried out to fully understand the different reactor performances of riser and downer in the application of FCC refining processes. It can be concluded that the downer benefits from its advantages of the plug-flow nature and uniform flow structures, tending to have more products in the middle distillates, e.g., gasoline and light olefins, especially under high-severity operations. Better control of the reaction extent for increased selectivity to desired intermediate products would allow the use of downer reactors for the larger-scale practical applications in the FCC process, together with the valuable byproduction of light olefins. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800168x

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Minimum fluidization velocity of a three-phase conical fluidized bed in comparison to a cylindrical fluidized bed / Dandan Zhou in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 27-36 Titre : Minimum fluidization velocity of a three-phase conical fluidized bed in comparison to a cylindrical fluidized bed Type de document : texte imprimé Auteurs : Dandan Zhou, Éditeur scientifique ; Shuangshi Dong, Éditeur scientifique ; Heli Wang, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 27-36 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fluidization Conical fluidized cylindrical bed Minimum fluidization Résumé : Hydrodynamic characteristics of a gas−liquid−solid conical fluidized bed were studied and compared with both liquid−solid conical beds and three-phase cylindrical fluidized beds. The effect of bubbles on particle mixing, pressure drop, and minimum fluidization velocity were discussed. Minimum fluidization velocities predicted by modified Ergun equation which accounts for the variation of the cross-sectional area with the bed height were found to be in good agreement with the liquid−solid conical fluidized bed data. The models of Song et al. [ Can. J. Chem. Eng.1989, 67, 265] and Zhang et al. [ Power Tech.1998, 100, 113; PhD. Thesis, 1996], derived originally for three-phase cylindrical fluidized beds, respectively, were modified for the prediction of Umf in a three-phase conical fluidized bed by accounting for the geometrical variation of the conical bed. It is found that the modified Song et al. model gave a better agreement than the modified Zhang et al. model in comparison with the current experimental data. However, the prediction of the modified Zhang et al. model is much improved when the parameter α, fractional gas holdup, was estimated using the equation from the Song et al. model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001974 [article] Minimum fluidization velocity of a three-phase conical fluidized bed in comparison to a cylindrical fluidized bed [texte imprimé] / Dandan Zhou, Éditeur scientifique ; Shuangshi Dong, Éditeur scientifique ; Heli Wang, Éditeur scientifique . - 2009 . - p. 27-36. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 27-36 Mots-clés : Fluidization Conical fluidized cylindrical bed Minimum fluidization Résumé : Hydrodynamic characteristics of a gas−liquid−solid conical fluidized bed were studied and compared with both liquid−solid conical beds and three-phase cylindrical fluidized beds. The effect of bubbles on particle mixing, pressure drop, and minimum fluidization velocity were discussed. Minimum fluidization velocities predicted by modified Ergun equation which accounts for the variation of the cross-sectional area with the bed height were found to be in good agreement with the liquid−solid conical fluidized bed data. The models of Song et al. [ Can. J. Chem. Eng.1989, 67, 265] and Zhang et al. [ Power Tech.1998, 100, 113; PhD. Thesis, 1996], derived originally for three-phase cylindrical fluidized beds, respectively, were modified for the prediction of Umf in a three-phase conical fluidized bed by accounting for the geometrical variation of the conical bed. It is found that the modified Song et al. model gave a better agreement than the modified Zhang et al. model in comparison with the current experimental data. However, the prediction of the modified Zhang et al. model is much improved when the parameter α, fractional gas holdup, was estimated using the equation from the Song et al. model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001974

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Residence time distribution and flow patterns in the single-phase annular region of annular centrifugal extractor / Sandesh S. Deshmukh in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 37-46 Titre : Residence time distribution and flow patterns in the single-phase annular region of annular centrifugal extractor Type de document : texte imprimé Auteurs : Sandesh S. Deshmukh, Éditeur scientifique ; Mayur J. Sathe, Éditeur scientifique ; Jyeshtharaj B. Joshi, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 37-46 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Two concentric cylinders Residence time distribution Annular centrifugal extractor Résumé : Flow between two concentric cylinders with high-speed rotation of the inner cylinder, also termed as turbulent Taylor−Couette flow, is an integral part of annular centrifugal extractor (ACE). The vortex motion in the annular region causes intense mixing, of the two liquids, and their separation occurs in the inner cylinder under centrifugal action. In the present work, a systematic study of residence time distribution (RTD) in the annular region of ACE has been carried out experimentally as well as using computational fluid dynamics (CFD). The effects of rotational speed (10 ≤ ω ≤ 40, r/s), aspect ratio of annulus (11 ≤ Γ ≤ 48), width of annular gap (1.5 ≤ d ≤ 6.5, mm), and the flow ratio of the immiscible fluids (0.73 ≤ FR ≤ 2.4) have been systematically investigated. Effect of flow ratio, annular gap, and rotational speed has been investigated on the RTD. It was found that the flow in ACE is near to back-mixed behavior because of the presence of counterrotating vortices. The number of vortices depends on the rotational speed and the geometrical parameters of ACE. An attempt has been made to reduce back-mixing by providing radial baffles in the annulus. Good agreement was observed between the experimental measurements and CFD predictions of RTD. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800231d [article] Residence time distribution and flow patterns in the single-phase annular region of annular centrifugal extractor [texte imprimé] / Sandesh S. Deshmukh, Éditeur scientifique ; Mayur J. Sathe, Éditeur scientifique ; Jyeshtharaj B. Joshi, Éditeur scientifique . - 2009 . - p. 37-46. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 37-46 Mots-clés : Two concentric cylinders Residence time distribution Annular centrifugal extractor Résumé : Flow between two concentric cylinders with high-speed rotation of the inner cylinder, also termed as turbulent Taylor−Couette flow, is an integral part of annular centrifugal extractor (ACE). The vortex motion in the annular region causes intense mixing, of the two liquids, and their separation occurs in the inner cylinder under centrifugal action. In the present work, a systematic study of residence time distribution (RTD) in the annular region of ACE has been carried out experimentally as well as using computational fluid dynamics (CFD). The effects of rotational speed (10 ≤ ω ≤ 40, r/s), aspect ratio of annulus (11 ≤ Γ ≤ 48), width of annular gap (1.5 ≤ d ≤ 6.5, mm), and the flow ratio of the immiscible fluids (0.73 ≤ FR ≤ 2.4) have been systematically investigated. Effect of flow ratio, annular gap, and rotational speed has been investigated on the RTD. It was found that the flow in ACE is near to back-mixed behavior because of the presence of counterrotating vortices. The number of vortices depends on the rotational speed and the geometrical parameters of ACE. An attempt has been made to reduce back-mixing by providing radial baffles in the annulus. Good agreement was observed between the experimental measurements and CFD predictions of RTD. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800231d

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Euler-euler modeling of flow, mass transfer, and chemical reaction in a bubble column / Dongsheng Zhang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 47-57 Titre : Euler-euler modeling of flow, mass transfer, and chemical reaction in a bubble column Type de document : texte imprimé Auteurs : Dongsheng Zhang, Éditeur scientifique ; Niels G. Deen, Éditeur scientifique ; J. A. M. Kuipers, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 47-57 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chemical Reaction Physical and chemical absorption CO2 Résumé : Physical and chemical absorption of pure CO2 bubbles in water and an aqueous sodium hydroxide (NaOH) solution has been studied in a square cross-sectioned bubble column using the commercial software package CFX-4.4. The subgrid-scale turbulence model of Vreman [Phys. Fluids 2004, 16, 3670−3681] was employed to evaluate the shear-induced turbulent viscosity in the liquid phase. An “opening” boundary condition was applied at the outlet, whereas the previously studied interfacial coefficients were used in the simulations. Full coupling of fluid flow, mass transfer, and chemical reaction is achieved through the incorporation of a bubble number density equation. The capability of the bubble number density model to predict the bubble size is investigated first. Subsequently, physical absorption of pure CO2 in water and chemisorption of pure CO2 bubbles in an aqueous NaOH solution are numerically studied. It was verified for a test case without absorption that the specified bubble size can be reproduced with the aid of a bubble number density equation. For the physical absorption of CO2 in water, it is found that generally the size of the bubbles in the core of the bubble plume is larger than that of the bubbles trapped in the downflow along the wall. In this test case, the bubble size ranges from 3 to 4 mm. As time proceeds, the differences in bubble size become smaller in both the horizontal and vertical directions. When pure CO2 is absorbed into an aqueous NaOH solution with an initial pH value of 12, the bubble size does not change very much with time. In this case, the bubble size ranges from 2.7 to 4 mm because the mass-transfer enhancement factor is on the order of unity, as a result of the relatively low pH. The pH history resulting from the numerical model is compared to that obtained from a simple macroscopic model. It is found that numerical results obtained from the case in which the bubble size is solved agree well with the simple model. The observed differences between the simple model and the simulated results obtained with constant bubble size are due to the lack of coupling of mass transfer and fluid flow. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800233y [article] Euler-euler modeling of flow, mass transfer, and chemical reaction in a bubble column [texte imprimé] / Dongsheng Zhang, Éditeur scientifique ; Niels G. Deen, Éditeur scientifique ; J. A. M. Kuipers, Éditeur scientifique . - 2009 . - p. 47-57. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 47-57 Mots-clés : Chemical Reaction Physical and chemical absorption CO2 Résumé : Physical and chemical absorption of pure CO2 bubbles in water and an aqueous sodium hydroxide (NaOH) solution has been studied in a square cross-sectioned bubble column using the commercial software package CFX-4.4. The subgrid-scale turbulence model of Vreman [Phys. Fluids 2004, 16, 3670−3681] was employed to evaluate the shear-induced turbulent viscosity in the liquid phase. An “opening” boundary condition was applied at the outlet, whereas the previously studied interfacial coefficients were used in the simulations. Full coupling of fluid flow, mass transfer, and chemical reaction is achieved through the incorporation of a bubble number density equation. The capability of the bubble number density model to predict the bubble size is investigated first. Subsequently, physical absorption of pure CO2 in water and chemisorption of pure CO2 bubbles in an aqueous NaOH solution are numerically studied. It was verified for a test case without absorption that the specified bubble size can be reproduced with the aid of a bubble number density equation. For the physical absorption of CO2 in water, it is found that generally the size of the bubbles in the core of the bubble plume is larger than that of the bubbles trapped in the downflow along the wall. In this test case, the bubble size ranges from 3 to 4 mm. As time proceeds, the differences in bubble size become smaller in both the horizontal and vertical directions. When pure CO2 is absorbed into an aqueous NaOH solution with an initial pH value of 12, the bubble size does not change very much with time. In this case, the bubble size ranges from 2.7 to 4 mm because the mass-transfer enhancement factor is on the order of unity, as a result of the relatively low pH. The pH history resulting from the numerical model is compared to that obtained from a simple macroscopic model. It is found that numerical results obtained from the case in which the bubble size is solved agree well with the simple model. The observed differences between the simple model and the simulated results obtained with constant bubble size are due to the lack of coupling of mass transfer and fluid flow. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800233y

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Computed tomographic investigation of the influence of gas sparger design on gas holdup distribution in a bubble column / B. C. Ong in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 58-68 Titre : Computed tomographic investigation of the influence of gas sparger design on gas holdup distribution in a bubble column Type de document : texte imprimé Auteurs : B. C. Ong, Éditeur scientifique ; P. Gupta, Éditeur scientifique ; A. Youssef, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 58-68 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Computed tomographic investigation Gas sparger design Résumé : The effect of gas sparger design on the gas holdup radial profile in a bubble column (with a diameter of 0.162 m) has been studied using γ-ray computed tomography (CT). Six different configurations of gas spargers were examined, using an air−water system for selected superficial gas velocities from 2 cm/s to 30 cm/s, covering the homogeneous and heterogeneous (churn-turbulent) flow regimes. Two operating pressures were used: 1 and 4 atm. Differences were found between the gas holdup distributions produced by different spargers at dimensionless radii of r/R En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800516s [article] Computed tomographic investigation of the influence of gas sparger design on gas holdup distribution in a bubble column [texte imprimé] / B. C. Ong, Éditeur scientifique ; P. Gupta, Éditeur scientifique ; A. Youssef, Éditeur scientifique . - 2009 . - p. 58-68. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 58-68 Mots-clés : Computed tomographic investigation Gas sparger design Résumé : The effect of gas sparger design on the gas holdup radial profile in a bubble column (with a diameter of 0.162 m) has been studied using γ-ray computed tomography (CT). Six different configurations of gas spargers were examined, using an air−water system for selected superficial gas velocities from 2 cm/s to 30 cm/s, covering the homogeneous and heterogeneous (churn-turbulent) flow regimes. Two operating pressures were used: 1 and 4 atm. Differences were found between the gas holdup distributions produced by different spargers at dimensionless radii of r/R En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800516s

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Active regeneration of diesel particulate filter employing microwave heating / Sameer Pallavkar in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 69-79 Titre : Active regeneration of diesel particulate filter employing microwave heating Type de document : texte imprimé Auteurs : Sameer Pallavkar, Éditeur scientifique ; Tae-Hoon Kim, Éditeur scientifique ; Dan Rutman, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 69-79 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Diesel particulate filter Microwave heating Résumé : Wall-flow diesel particulate filters (DPFs) are considered the most effective devices for the control of diesel particulate emissions. A requirement for the reliable operation of the DPFs, however, is the periodic and/or continuous regeneration of the filters. While microwave heating has been considered a potential active regeneration method for the DPFs, past studies on the technology have identified several technical problems leading to filter failure. The problems are mainly associated with the use of inappropriate filter materials for the microwave system and the generation of local hotspots due to uneven microwave heating, resulting in the physical damage to the filters. The objective of this study was to develop and demonstrate the technology employing a microwave-absorbing filter material coupled with an effective waveguide design for the reliable regeneration of DPFs. In this study, a well-equipped diesel emission control laboratory was established to conduct the experiments. The experimental facilities included a 6-kWe diesel generator, an exhaust flow control system, a diesel particulate filter system, a microwave energy supply system, a soot sampling system, a differential-pressure measurement system, and a temperature measurement system. The DPF was a silicone carbide wall-flow monolith filter enclosed in a quartz filter holder. A commercial 1.4-kWe microwave oven was modified to accommodate the quartz holder and a waveguide was engineered to evenly supply the microwave energy to the enclosed filter to achieve filter regeneration. In the experiments, the diesel engine exhaust was lined up to flow through the filter with a fixed flow rate. The microwave regeneration was triggered after a specific amount of soot loading was reached based on the differential pressure drop reading. The results have indicated that the designed system has been able to achieve uniform temperature profiles both in the radial and the vertical DPF positions. The off-line regeneration of DPF by microwave energy has been observed to be highly efficient in terms of energy consumption and regeneration efficiency. The DPM filtration efficiency has remained comparably high after 150 cycles of filtration/regeneration with no apparent physical damage to the DPF being observed. The on-line microwave regeneration of the DPF, however, is not as efficient as the off-line regeneration due to the insufficient oxygen concentration in the engine exhaust stream. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800780g [article] Active regeneration of diesel particulate filter employing microwave heating [texte imprimé] / Sameer Pallavkar, Éditeur scientifique ; Tae-Hoon Kim, Éditeur scientifique ; Dan Rutman, Éditeur scientifique . - 2009 . - p. 69-79. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 69-79 Mots-clés : Diesel particulate filter Microwave heating Résumé : Wall-flow diesel particulate filters (DPFs) are considered the most effective devices for the control of diesel particulate emissions. A requirement for the reliable operation of the DPFs, however, is the periodic and/or continuous regeneration of the filters. While microwave heating has been considered a potential active regeneration method for the DPFs, past studies on the technology have identified several technical problems leading to filter failure. The problems are mainly associated with the use of inappropriate filter materials for the microwave system and the generation of local hotspots due to uneven microwave heating, resulting in the physical damage to the filters. The objective of this study was to develop and demonstrate the technology employing a microwave-absorbing filter material coupled with an effective waveguide design for the reliable regeneration of DPFs. In this study, a well-equipped diesel emission control laboratory was established to conduct the experiments. The experimental facilities included a 6-kWe diesel generator, an exhaust flow control system, a diesel particulate filter system, a microwave energy supply system, a soot sampling system, a differential-pressure measurement system, and a temperature measurement system. The DPF was a silicone carbide wall-flow monolith filter enclosed in a quartz filter holder. A commercial 1.4-kWe microwave oven was modified to accommodate the quartz holder and a waveguide was engineered to evenly supply the microwave energy to the enclosed filter to achieve filter regeneration. In the experiments, the diesel engine exhaust was lined up to flow through the filter with a fixed flow rate. The microwave regeneration was triggered after a specific amount of soot loading was reached based on the differential pressure drop reading. The results have indicated that the designed system has been able to achieve uniform temperature profiles both in the radial and the vertical DPF positions. The off-line regeneration of DPF by microwave energy has been observed to be highly efficient in terms of energy consumption and regeneration efficiency. The DPM filtration efficiency has remained comparably high after 150 cycles of filtration/regeneration with no apparent physical damage to the DPF being observed. The on-line microwave regeneration of the DPF, however, is not as efficient as the off-line regeneration due to the insufficient oxygen concentration in the engine exhaust stream. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800780g

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Collective particle interactions in the sedimentation of charged colloidal suspensions / Jan Vesaratchanon in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 80-84 Titre : Collective particle interactions in the sedimentation of charged colloidal suspensions Type de document : texte imprimé Auteurs : Jan Vesaratchanon, Éditeur scientifique ; Alex Nikolov, Éditeur scientifique ; Darsh T. Wasan, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 80-84 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sedimentation Monodisperse colloidal Microstructure formation Résumé : The sedimentation of a similarly charged monodisperse colloidal suspension was studied to investigate the role of collective particle interactions affecting the rate of sedimentation and thereby the stability. The particle concentration profiles, microstructure formation, and the sedimentation rates were determined using a nondestructive back-light scattering technique. Stochastic particle dynamics simulations using the Beresford-Smith and Derjaguin−Landau−Verwey−Overbeek repulsive pair potentials were carried out to predict the sedimentation rates. In addition, Monte Carlo simulations were performed to reveal the particle microstructure formation. The collective particle interactions result in an oscillatory effective potential of interaction between the identically charged particles, even though the pair potential is repulsive, and lead to a more ordered microstructure formation and reduction in the sedimentation rate. The theoretical predictions, which were in good agreement with the experimental measurements, clearly showed the importance of the collective particle interaction effect in stabilizing the monodisperse suspension. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004176 [article] Collective particle interactions in the sedimentation of charged colloidal suspensions [texte imprimé] / Jan Vesaratchanon, Éditeur scientifique ; Alex Nikolov, Éditeur scientifique ; Darsh T. Wasan, Éditeur scientifique . - 2009 . - p. 80-84. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 80-84 Mots-clés : Sedimentation Monodisperse colloidal Microstructure formation Résumé : The sedimentation of a similarly charged monodisperse colloidal suspension was studied to investigate the role of collective particle interactions affecting the rate of sedimentation and thereby the stability. The particle concentration profiles, microstructure formation, and the sedimentation rates were determined using a nondestructive back-light scattering technique. Stochastic particle dynamics simulations using the Beresford-Smith and Derjaguin−Landau−Verwey−Overbeek repulsive pair potentials were carried out to predict the sedimentation rates. In addition, Monte Carlo simulations were performed to reveal the particle microstructure formation. The collective particle interactions result in an oscillatory effective potential of interaction between the identically charged particles, even though the pair potential is repulsive, and lead to a more ordered microstructure formation and reduction in the sedimentation rate. The theoretical predictions, which were in good agreement with the experimental measurements, clearly showed the importance of the collective particle interaction effect in stabilizing the monodisperse suspension. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004176

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Role of gas-aerosol mixing during in situ coating of flame-made titania particles / Alexandra Teleki in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 85-92 Titre : Role of gas-aerosol mixing during in situ coating of flame-made titania particles Type de document : texte imprimé Auteurs : Alexandra Teleki, Éditeur scientifique ; Beat Buesser, Éditeur scientifique ; Martin C. Heine, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 85-92 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-aerosol Flame Titania X-ray Photocatalysis Résumé : Rutile TiO2 particles of 40 nm average diameter were made by flame spray pyrolysis (FSP) and in situ coated with ultrathin (2−4 nm) SiO2 layers. The spray flame was enclosed by a quartz glass tube while hexamethyldisiloxane (HMDSO) vapor-laden N2 was injected in swirling crossflow to and downstream of the flame through a metal torus pipe ring. The as-prepared powders were characterized by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption. The effect of mixing between HMDSO-laden N2 jets and freshly made titania aerosol on product coating quality was investigated by varying systematically the number and gas flowrate through these jets experimentally and by computational fluid dynamics. The coating quality of titanium dioxide was evaluated further by photocatalysis of isopropanol to acetone under UV light using suspensions of the above particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800226d [article] Role of gas-aerosol mixing during in situ coating of flame-made titania particles [texte imprimé] / Alexandra Teleki, Éditeur scientifique ; Beat Buesser, Éditeur scientifique ; Martin C. Heine, Éditeur scientifique . - 2009 . - p. 85-92. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 85-92 Mots-clés : Gas-aerosol Flame Titania X-ray Photocatalysis Résumé : Rutile TiO2 particles of 40 nm average diameter were made by flame spray pyrolysis (FSP) and in situ coated with ultrathin (2−4 nm) SiO2 layers. The spray flame was enclosed by a quartz glass tube while hexamethyldisiloxane (HMDSO) vapor-laden N2 was injected in swirling crossflow to and downstream of the flame through a metal torus pipe ring. The as-prepared powders were characterized by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption. The effect of mixing between HMDSO-laden N2 jets and freshly made titania aerosol on product coating quality was investigated by varying systematically the number and gas flowrate through these jets experimentally and by computational fluid dynamics. The coating quality of titanium dioxide was evaluated further by photocatalysis of isopropanol to acetone under UV light using suspensions of the above particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800226d

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Effect of high shear blending protocols and blender parameters on the degree of API agglomeration in solid formulations / Marcos Llusa in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 93-101 Titre : Effect of high shear blending protocols and blender parameters on the degree of API agglomeration in solid formulations Type de document : texte imprimé Auteurs : Marcos Llusa, Éditeur scientifique ; Kurt Sturm, Éditeur scientifique ; Osama Sudah, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 93-101 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Active pharmaceutical ingredient (API) API agglomeration Solid formulations Résumé : This paper examines the effect of three protocols with several units and blender parameters on the mitigation of active pharmaceutical ingredient (API) agglomeration in solid formulations. The three protocols either preblend API with a portion of excipients in a high shear unit followed by dilution in a large blender or prepare the entire blend in a single blender followed by milling. In general, the three protocols yield blends with statistically similar API concentration variance and deagglomeration. The scale-up of the three protocols leads to more extensive API deagglomeration, which suggests that blender parameters still influence the degree of API deagglomeration, even when high shear units are present in the protocol. Lower blender fill levels and larger blenders lead to blends with fewer API agglomerates. Regarding the use of blender internals, results show that baffles have no substantial effect on API agglomeration. The inclusion of a moving internal (i.e., impeller) in a bin blender may not always lead to blends with fewer API agglomerates. The design and the positioning of the impeller play an important role as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007055 [article] Effect of high shear blending protocols and blender parameters on the degree of API agglomeration in solid formulations [texte imprimé] / Marcos Llusa, Éditeur scientifique ; Kurt Sturm, Éditeur scientifique ; Osama Sudah, Éditeur scientifique . - 2009 . - p. 93-101. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 93-101 Mots-clés : Active pharmaceutical ingredient (API) API agglomeration Solid formulations Résumé : This paper examines the effect of three protocols with several units and blender parameters on the mitigation of active pharmaceutical ingredient (API) agglomeration in solid formulations. The three protocols either preblend API with a portion of excipients in a high shear unit followed by dilution in a large blender or prepare the entire blend in a single blender followed by milling. In general, the three protocols yield blends with statistically similar API concentration variance and deagglomeration. The scale-up of the three protocols leads to more extensive API deagglomeration, which suggests that blender parameters still influence the degree of API deagglomeration, even when high shear units are present in the protocol. Lower blender fill levels and larger blenders lead to blends with fewer API agglomerates. Regarding the use of blender internals, results show that baffles have no substantial effect on API agglomeration. The inclusion of a moving internal (i.e., impeller) in a bin blender may not always lead to blends with fewer API agglomerates. The design and the positioning of the impeller play an important role as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007055

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Preliminary assessment of a concept of looping combustion of carbon / Piero Salatino in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 102-109 Titre : Preliminary assessment of a concept of looping combustion of carbon Type de document : texte imprimé Auteurs : Piero Salatino, Éditeur scientifique ; Osvalda Senneca, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 102-109 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Looping Combustion of Carbon (CarboLoop) Feature carbons Surface oxides carbon products (CO, CO2) CarboLoop Résumé : A novel concept of looping combustion of carbon (CarboLoop) is presented. It is based on the feature of carbons to extensively uptake oxygen upon exposure to air at moderate temperatures. Surface oxides of carbon are eventually released as combustion products (CO, CO2) as the oxidized fuel is brought to moderate-to-high temperature in an oxygen-free atmosphere. This concept is pursued to the formulation of a preliminary scheme of a looping combustor of carbons based on a dual interconnected bed reactor system. One of the reactors is air-blown and acts as the fuel oxidizer. The second reactor, operated with partial recycle of gaseous effluents (CO2 + impurities), acts as the fuel desorber. Operating conditions of the oxidation and desorption stages may be properly tuned, leading to alternative looping strategies. The present study lays down the basic mechanistic background for analyzing the process, based on a simplified semiglobal approach to combustion and oxidation of solid carbons. The soundness of the CarboLoop concept has been verified by purposely designed experiments. The alternated oxidation/desorption stages typical of a looping combustor are simulated in a thermogravimetric analyzer. Experiments were directed to monitoring the oxidation and desorption steps under simulated looping conditions. Graphitized coke has been used as a surrogate carbon fuel. The experimental results confirm the soundness and potential of the CarboLoop concept and lay the path for its further development. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800295q [article] Preliminary assessment of a concept of looping combustion of carbon [texte imprimé] / Piero Salatino, Éditeur scientifique ; Osvalda Senneca, Éditeur scientifique . - 2009 . - p. 102-109. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 102-109 Mots-clés : Looping Combustion of Carbon (CarboLoop) Feature carbons Surface oxides carbon products (CO, CO2) CarboLoop Résumé : A novel concept of looping combustion of carbon (CarboLoop) is presented. It is based on the feature of carbons to extensively uptake oxygen upon exposure to air at moderate temperatures. Surface oxides of carbon are eventually released as combustion products (CO, CO2) as the oxidized fuel is brought to moderate-to-high temperature in an oxygen-free atmosphere. This concept is pursued to the formulation of a preliminary scheme of a looping combustor of carbons based on a dual interconnected bed reactor system. One of the reactors is air-blown and acts as the fuel oxidizer. The second reactor, operated with partial recycle of gaseous effluents (CO2 + impurities), acts as the fuel desorber. Operating conditions of the oxidation and desorption stages may be properly tuned, leading to alternative looping strategies. The present study lays down the basic mechanistic background for analyzing the process, based on a simplified semiglobal approach to combustion and oxidation of solid carbons. The soundness of the CarboLoop concept has been verified by purposely designed experiments. The alternated oxidation/desorption stages typical of a looping combustor are simulated in a thermogravimetric analyzer. Experiments were directed to monitoring the oxidation and desorption steps under simulated looping conditions. Graphitized coke has been used as a surrogate carbon fuel. The experimental results confirm the soundness and potential of the CarboLoop concept and lay the path for its further development. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800295q

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Viscous irrotational theories and the force on an expanding bubble / Juan C. Padrino in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 110-127 Titre : Viscous irrotational theories and the force on an expanding bubble : a cell-model analysis Type de document : texte imprimé Auteurs : Juan C. Padrino, Éditeur scientifique ; Daniel D. Joseph, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 110-127 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Irrotational Theories Viscous incompressible fluid Résumé : The dynamics of a bounded viscous incompressible fluid surrounding a spherical bubble in rectilinear motion simultaneously experiencing volume changes is examined by means of two viscous irrotational theories, namely, viscous potential flow and the dissipation method. The forces that the liquid produces on the bubble and on the outer spherical boundary of the liquid are determined from these two approaches at the instant when the bubble is concentric with the outer surface. Viscous potential flow involves surface integration of the irrotational normal stress; the dissipation method stems from the mechanical energy balance, including the dissipation integral, evaluated in potential flow. In the inner boundary, zero tangential stress is enforced. Two choices for the tangential stress condition on the outer boundary are considered: zero tangential stress or irrotational tangential stress. In a sense, this is an extension to include viscous effects of the inviscid analysis by Sherwood [Int. J. Multiphase Flow, 1999, 25, 705]. The potential flow that follows from Sherwood’s work is used in the derived formulas to compute the drag. To the added-mass forces associated with the bubble acceleration and rate of change of the bubble radius determined by Sherwood, a viscous contribution is added here that is dependent on the instantaneous bubble velocity and the inner and outer instantaneous radii of the bubble-liquid cell. When the outer radius is taken to infinity, the expressions for the drag yield results given in the literature. If the inner and outer radii are held fixed, results from the cell model may be used to approximate the drag on a bubble moving in a bubbly suspension with the same volume fraction as the cell. The analysis yields two results for the viscous drag on the bubble, contingent on the boundary condition applied on the outer sphere. These formulas have been presented in the literature, although regarded as contradictories. By emphasizing the role of the tangential stress on the outer boundary, it is shown that both results are valid, because they are dependent on the choice of the outer dynamic boundary condition. These results agree to first order in the volume fraction. The terminal rise velocity of a bubble swarm is derived using the drag from the viscous irrotational theories. Results for the drag coefficient and bubble rise velocity are compared with other theoretical results, as well as data from numerical simulations and experiments, with emphasis in the regime of high Reynolds and low Weber numbers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800251j [article] Viscous irrotational theories and the force on an expanding bubble : a cell-model analysis [texte imprimé] / Juan C. Padrino, Éditeur scientifique ; Daniel D. Joseph, Éditeur scientifique . - 2009 . - p. 110-127. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 110-127 Mots-clés : Irrotational Theories Viscous incompressible fluid Résumé : The dynamics of a bounded viscous incompressible fluid surrounding a spherical bubble in rectilinear motion simultaneously experiencing volume changes is examined by means of two viscous irrotational theories, namely, viscous potential flow and the dissipation method. The forces that the liquid produces on the bubble and on the outer spherical boundary of the liquid are determined from these two approaches at the instant when the bubble is concentric with the outer surface. Viscous potential flow involves surface integration of the irrotational normal stress; the dissipation method stems from the mechanical energy balance, including the dissipation integral, evaluated in potential flow. In the inner boundary, zero tangential stress is enforced. Two choices for the tangential stress condition on the outer boundary are considered: zero tangential stress or irrotational tangential stress. In a sense, this is an extension to include viscous effects of the inviscid analysis by Sherwood [Int. J. Multiphase Flow, 1999, 25, 705]. The potential flow that follows from Sherwood’s work is used in the derived formulas to compute the drag. To the added-mass forces associated with the bubble acceleration and rate of change of the bubble radius determined by Sherwood, a viscous contribution is added here that is dependent on the instantaneous bubble velocity and the inner and outer instantaneous radii of the bubble-liquid cell. When the outer radius is taken to infinity, the expressions for the drag yield results given in the literature. If the inner and outer radii are held fixed, results from the cell model may be used to approximate the drag on a bubble moving in a bubbly suspension with the same volume fraction as the cell. The analysis yields two results for the viscous drag on the bubble, contingent on the boundary condition applied on the outer sphere. These formulas have been presented in the literature, although regarded as contradictories. By emphasizing the role of the tangential stress on the outer boundary, it is shown that both results are valid, because they are dependent on the choice of the outer dynamic boundary condition. These results agree to first order in the volume fraction. The terminal rise velocity of a bubble swarm is derived using the drag from the viscous irrotational theories. Results for the drag coefficient and bubble rise velocity are compared with other theoretical results, as well as data from numerical simulations and experiments, with emphasis in the regime of high Reynolds and low Weber numbers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800251j

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Gas-phase catalytic hydrochlorination of acetylene in a two-stage fluidized-bed reactor / Xiaobo Wei in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 128-133 Titre : Gas-phase catalytic hydrochlorination of acetylene in a two-stage fluidized-bed reactor Type de document : texte imprimé Auteurs : Xiaobo Wei, Éditeur scientifique ; Haibo Shi, Éditeur scientifique ; Weizhong Qian, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 128-133 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-Phase Catalytic Vinyl chloride Industrial catalyst Résumé : Production of vinyl chloride monomer (VCM) by the hydrochlorination of acetylene with HCl was investigated in both a single-stage fluidized bed (SSFB) and a two-stage fluidized bed (TSFB) at different reaction temperatures and space velocities of acetylene. The conversion of acetylene increases with increasing temperature and decreases with increasing space velocity. Over a wide range of operating conditions, a higher conversion of acetylene was achieved in the TSFB than in the SSFB, with the selectivity of VCM being almost 100%. This process can be described by a two-dimensional dispersion and reaction model. A new catalyst, HgCl2 supported on a coconut-shell-type activated carbon, which has a much higher mechanical strength than the industrial catalyst (HgCl2 supported on a coal-based activated carbon), was employed in the fluidized beds. Evaluation of the catalyst lifetime in a fast sublimation experiment at high temperature showed that the new catalyst has a longer lifetime than the industrial catalyst. The novel TSFB technology, combined with the new catalyst, is effective in providing a higher throughput and quality of the VCM product than the conventional PB reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716316 [article] Gas-phase catalytic hydrochlorination of acetylene in a two-stage fluidized-bed reactor [texte imprimé] / Xiaobo Wei, Éditeur scientifique ; Haibo Shi, Éditeur scientifique ; Weizhong Qian, Éditeur scientifique . - 2009 . - p. 128-133. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 128-133 Mots-clés : Gas-Phase Catalytic Vinyl chloride Industrial catalyst Résumé : Production of vinyl chloride monomer (VCM) by the hydrochlorination of acetylene with HCl was investigated in both a single-stage fluidized bed (SSFB) and a two-stage fluidized bed (TSFB) at different reaction temperatures and space velocities of acetylene. The conversion of acetylene increases with increasing temperature and decreases with increasing space velocity. Over a wide range of operating conditions, a higher conversion of acetylene was achieved in the TSFB than in the SSFB, with the selectivity of VCM being almost 100%. This process can be described by a two-dimensional dispersion and reaction model. A new catalyst, HgCl2 supported on a coconut-shell-type activated carbon, which has a much higher mechanical strength than the industrial catalyst (HgCl2 supported on a coal-based activated carbon), was employed in the fluidized beds. Evaluation of the catalyst lifetime in a fast sublimation experiment at high temperature showed that the new catalyst has a longer lifetime than the industrial catalyst. The novel TSFB technology, combined with the new catalyst, is effective in providing a higher throughput and quality of the VCM product than the conventional PB reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716316

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Prediction of solids circulation rate of cork particles in an ambient-pressure pilot-scale circulating fluidized bed / Yue Huang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 134-141 Titre : Prediction of solids circulation rate of cork particles in an ambient-pressure pilot-scale circulating fluidized bed Type de document : texte imprimé Auteurs : Yue Huang, Éditeur scientifique ; Richard Turton, Éditeur scientifique ; Parviz Famouri, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 134-141 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solids Circulation Cork Particles Circulating fluidized beds (CFB) Standpipe particles Résumé : Circulating fluidized beds (CFB) are currently used in many industrial processes for noncatalytic and catalytic gas-solid reactions. The prediction of solids flow rate is important because its effective control is the key to smooth operation of a CFB system. This paper presents a method for solids flow metering from pressure drop measurements in the standpipe dense phase. A model based on the Ergun equation is developed to predict the solids flow rate and voidage in the dense phase of the standpipe. The profile of the solids flow rate under unsteady state is also presented. With the use of this method, the dynamic response time at different locations along the standpipe of a pilot-scale fluidized bed operating at ambient conditions with 812 μm cork particles is estimated successfully. Through the use of a pressure balance analysis, solids flow models for the standpipe, riser, and other sections of the flow loop are combined to give an integrated CFB model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001843 [article] Prediction of solids circulation rate of cork particles in an ambient-pressure pilot-scale circulating fluidized bed [texte imprimé] / Yue Huang, Éditeur scientifique ; Richard Turton, Éditeur scientifique ; Parviz Famouri, Éditeur scientifique . - 2009 . - p. 134-141. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 134-141 Mots-clés : Solids Circulation Cork Particles Circulating fluidized beds (CFB) Standpipe particles Résumé : Circulating fluidized beds (CFB) are currently used in many industrial processes for noncatalytic and catalytic gas-solid reactions. The prediction of solids flow rate is important because its effective control is the key to smooth operation of a CFB system. This paper presents a method for solids flow metering from pressure drop measurements in the standpipe dense phase. A model based on the Ergun equation is developed to predict the solids flow rate and voidage in the dense phase of the standpipe. The profile of the solids flow rate under unsteady state is also presented. With the use of this method, the dynamic response time at different locations along the standpipe of a pilot-scale fluidized bed operating at ambient conditions with 812 μm cork particles is estimated successfully. Through the use of a pressure balance analysis, solids flow models for the standpipe, riser, and other sections of the flow loop are combined to give an integrated CFB model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001843

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Desulfurization of jet fuel JP-5 light fraction by MCM-41 and SBA-15 supported cuprous oxide for fuel cell applications / Yuhe Wang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 142-147 Titre : Desulfurization of jet fuel JP-5 light fraction by MCM-41 and SBA-15 supported cuprous oxide for fuel cell applications Type de document : texte imprimé Auteurs : Yuhe Wang, Éditeur scientifique ; Ralph T. Yang, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 142-147 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sulfur Desulfurization fuel Résumé : Desulfurization of a JP-5 light fraction (841 ppmw S) for on-board fuel cell applications was investigated by π-complexation adsorption with mesoporous SBA-15 and MCM-41 supported Cu2O. The effect of support and reduction temperature on the sulfur adsorption capacity was studied. The adsorbents were characterized with N2 physical adsorption and CO chemisorption. The results showed that the mesoporous structures of the support remained intact during adsorbent preparation. It was found that significant breakthrough occurred at 10.0 mL/g for desulfurization of the JP-5 light fraction by Cu2O/MCM-41 reduced at 700 °C. The MCM-41 was more effective than SBA-15 as the support for Cu2O adsorbents in desulfurizaiton of jet fuel. The sulfur adsorption capacity increased with the reduction temperature. The spent Cu2O/MCM-41 was regenerated by heating in air and the regenerated adsorbent was tested for reuse. The results showed that ∼100% of the sulfur capacity could be recovered. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800208g [article] Desulfurization of jet fuel JP-5 light fraction by MCM-41 and SBA-15 supported cuprous oxide for fuel cell applications [texte imprimé] / Yuhe Wang, Éditeur scientifique ; Ralph T. Yang, Éditeur scientifique . - 2009 . - p. 142-147. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 142-147 Mots-clés : Sulfur Desulfurization fuel Résumé : Desulfurization of a JP-5 light fraction (841 ppmw S) for on-board fuel cell applications was investigated by π-complexation adsorption with mesoporous SBA-15 and MCM-41 supported Cu2O. The effect of support and reduction temperature on the sulfur adsorption capacity was studied. The adsorbents were characterized with N2 physical adsorption and CO chemisorption. The results showed that the mesoporous structures of the support remained intact during adsorbent preparation. It was found that significant breakthrough occurred at 10.0 mL/g for desulfurization of the JP-5 light fraction by Cu2O/MCM-41 reduced at 700 °C. The MCM-41 was more effective than SBA-15 as the support for Cu2O adsorbents in desulfurizaiton of jet fuel. The sulfur adsorption capacity increased with the reduction temperature. The spent Cu2O/MCM-41 was regenerated by heating in air and the regenerated adsorbent was tested for reuse. The results showed that ∼100% of the sulfur capacity could be recovered. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800208g

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Uniform flow in bubble columns / R. F. Mudde in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 148-158 Titre : Uniform flow in bubble columns Type de document : texte imprimé Auteurs : R. F. Mudde, Éditeur scientifique ; W. K. Harteveld, Éditeur scientifique ; H. E. A van den Akker, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 148-158 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Flow in Bubble Columns Optical glass fibers Liquid axial velocity field Gas Résumé : Uniform bubbly flow in a 15 cm bubble column is investigated. We use a special needle sparger consisting of 559 separate needles, uniformly distributed over the bottom. With this sparger, we can ensure that all bubbles generated are of the same size and that the bubble injection is very uniform over the entire bottom of the column. Detailed experiments are reported, using optical glass fibers to measure the local gas fraction and bubble size and velocity and using laser Doppler anemometry to measure the liquid axial velocity field. We find that the homogeneous flow regime extends up to a gas fraction of 55% well beyond the predictions of theory. The superficial gas velocity at which the homogeneous regime looses its stability depends on the water quality: fresh water looses its stability much earlier than old water. However, the gas fraction as a function of the superficial gas velocity is in the homogeneous regime independent of the water quality. The overall gas fraction can be described by a Richardson and Zaki type of relation or by the proposal by Garnier et al. We have indications that, at the point of instability, the bubble size has increased to a critical value at which the lift force reverses sign. This causes the radial gas fraction to change from flat with a small wall peaking to core peaking provoking the instability as suggested by Lucas et al. [ Chem. Eng. Technol. 2005, 60, 3609]. Alternatively, at higher gas fractions, the swarm gets denser and the bubble wakes get suppressed. According to Fox and co-workers [ Chem. Eng. Sci. 2007, 62, 3159], this causes the flow to lose its stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000748 [article] Uniform flow in bubble columns [texte imprimé] / R. F. Mudde, Éditeur scientifique ; W. K. Harteveld, Éditeur scientifique ; H. E. A van den Akker, Éditeur scientifique . - 2009 . - p. 148-158. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 148-158 Mots-clés : Flow in Bubble Columns Optical glass fibers Liquid axial velocity field Gas Résumé : Uniform bubbly flow in a 15 cm bubble column is investigated. We use a special needle sparger consisting of 559 separate needles, uniformly distributed over the bottom. With this sparger, we can ensure that all bubbles generated are of the same size and that the bubble injection is very uniform over the entire bottom of the column. Detailed experiments are reported, using optical glass fibers to measure the local gas fraction and bubble size and velocity and using laser Doppler anemometry to measure the liquid axial velocity field. We find that the homogeneous flow regime extends up to a gas fraction of 55% well beyond the predictions of theory. The superficial gas velocity at which the homogeneous regime looses its stability depends on the water quality: fresh water looses its stability much earlier than old water. However, the gas fraction as a function of the superficial gas velocity is in the homogeneous regime independent of the water quality. The overall gas fraction can be described by a Richardson and Zaki type of relation or by the proposal by Garnier et al. We have indications that, at the point of instability, the bubble size has increased to a critical value at which the lift force reverses sign. This causes the radial gas fraction to change from flat with a small wall peaking to core peaking provoking the instability as suggested by Lucas et al. [ Chem. Eng. Technol. 2005, 60, 3609]. Alternatively, at higher gas fractions, the swarm gets denser and the bubble wakes get suppressed. According to Fox and co-workers [ Chem. Eng. Sci. 2007, 62, 3159], this causes the flow to lose its stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000748

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Transient granular flows in an inclined rotating cylinder / David M. Scott in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 159-165 Titre : Transient granular flows in an inclined rotating cylinder : filling and emptying Type de document : texte imprimé Auteurs : David M. Scott, Éditeur scientifique ; John F. Davidson, Éditeur scientifique ; Sim Ee Cheah, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 159-165 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Transient Granular Flows granular materials Sand Poppy seeds Glass beads Résumé : This paper reports the results of an experimental and theoretical study into transient granular flows in an inclined, slowly rotating cylinder. The granular materials used were sand, poppy seeds, and glass beads. The following situations have been studied: (i) feeding an initially empty cylinder, (ii) emptying a cylinder which is initially in steady state with equal feed and discharge flow rates, and (iii) the motion of a localized pile of granular material through the cylinder. Axial profiles of bed depth and discharge flow rates have been measured. The mechanistic model used here has previously been used to describe the transient response to large step changes in feed rate, rotation speed and angle of inclination; it has no free parameters. There is good agreement between theory and experiment for sand and poppy seeds, but there are discrepancies for glass beads, which under some conditions flow in a different way from sand and poppy seeds. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800156r [article] Transient granular flows in an inclined rotating cylinder : filling and emptying [texte imprimé] / David M. Scott, Éditeur scientifique ; John F. Davidson, Éditeur scientifique ; Sim Ee Cheah, Éditeur scientifique . - 2009 . - p. 159-165. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 159-165 Mots-clés : Transient Granular Flows granular materials Sand Poppy seeds Glass beads Résumé : This paper reports the results of an experimental and theoretical study into transient granular flows in an inclined, slowly rotating cylinder. The granular materials used were sand, poppy seeds, and glass beads. The following situations have been studied: (i) feeding an initially empty cylinder, (ii) emptying a cylinder which is initially in steady state with equal feed and discharge flow rates, and (iii) the motion of a localized pile of granular material through the cylinder. Axial profiles of bed depth and discharge flow rates have been measured. The mechanistic model used here has previously been used to describe the transient response to large step changes in feed rate, rotation speed and angle of inclination; it has no free parameters. There is good agreement between theory and experiment for sand and poppy seeds, but there are discrepancies for glass beads, which under some conditions flow in a different way from sand and poppy seeds. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800156r

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Completing irving and kirkwood’s molecular theory of transport processes / Michael Peters in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 166-171 Titre : Completing irving and kirkwood’s molecular theory of transport processes : nonequilibrium entropy conservation Type de document : texte imprimé Auteurs : Michael Peters, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 166-171 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Irving and Kirkwood’s Nonequilibrium entropy Résumé : Following Irving and Kirkwood’s (J. Chem. Phys. 1950, 18, 817) classical approach to the statistical mechanics of transport processes and the conservation equations for mass, momentum, and energy, we introduce a particular dynamical variable for entropy and derive the general nonequilibrium entropy conservation equation. This particular formalism is shown to encompass both Boltzmann’s and Gibbs’ entropy definitions as special cases. Entropy generation is shown to follow from phase-space dimensionality loss and truncations or approximations in higher-order space, the latter of which is consistent with the thesis of Jaynes (Am. J. Phys. 1965, 33, 391). The general approach to entropy conservation given here not only completes Irving and Kirkwood’s treatment of the transport equations but also allows for a consistent analysis of all transport equations for any given system. Following standard perturbation expansion methods about local equilibrium states, we derive the closed form of the entropy conservation equation for isolated systems, which is shown to be in agreement with well-known phenomenological results and the principles of irreversible thermodynamics. In addition, the generalized nonequilibrium entropy developed here is fully consistent with its equilibrium counterpart. As an example, our formalism allows the analysis of entropy changes in dense gases and liquids through the introduction of a nonequilibrium Green’s entropy. This study provides a firm molecular basis of entropy conservation by consistent methods across the transport equations, allowing ready extensions to complex systems. Such foundations are of contemporary importance in designing energy-efficient or minimum entropy generating engineering systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800170s [article] Completing irving and kirkwood’s molecular theory of transport processes : nonequilibrium entropy conservation [texte imprimé] / Michael Peters, Éditeur scientifique . - 2009 . - p. 166-171. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 166-171 Mots-clés : Irving and Kirkwood’s Nonequilibrium entropy Résumé : Following Irving and Kirkwood’s (J. Chem. Phys. 1950, 18, 817) classical approach to the statistical mechanics of transport processes and the conservation equations for mass, momentum, and energy, we introduce a particular dynamical variable for entropy and derive the general nonequilibrium entropy conservation equation. This particular formalism is shown to encompass both Boltzmann’s and Gibbs’ entropy definitions as special cases. Entropy generation is shown to follow from phase-space dimensionality loss and truncations or approximations in higher-order space, the latter of which is consistent with the thesis of Jaynes (Am. J. Phys. 1965, 33, 391). The general approach to entropy conservation given here not only completes Irving and Kirkwood’s treatment of the transport equations but also allows for a consistent analysis of all transport equations for any given system. Following standard perturbation expansion methods about local equilibrium states, we derive the closed form of the entropy conservation equation for isolated systems, which is shown to be in agreement with well-known phenomenological results and the principles of irreversible thermodynamics. In addition, the generalized nonequilibrium entropy developed here is fully consistent with its equilibrium counterpart. As an example, our formalism allows the analysis of entropy changes in dense gases and liquids through the introduction of a nonequilibrium Green’s entropy. This study provides a firm molecular basis of entropy conservation by consistent methods across the transport equations, allowing ready extensions to complex systems. Such foundations are of contemporary importance in designing energy-efficient or minimum entropy generating engineering systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800170s

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Comparison of ECVT and MR measurements of voidage in a gas-fluidized bed / D. J. Holland in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 172-181 Titre : Comparison of ECVT and MR measurements of voidage in a gas-fluidized bed Type de document : texte imprimé Auteurs : D. J. Holland, Éditeur scientifique ; Q. Marashdeh, Éditeur scientifique ; C. R. Müller, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 172-181 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Magnetic resonance (MR) Electrical capacitance volume tomography (ECVT) Gas-fluidized Résumé : This paper reports the first quantitative comparison of magnetic resonance (MR) and electrical capacitance volume tomography (ECVT) on a 50 mm diameter gas-fluidized bed of silica−alumina catalyst support particles (dp = 58 μm). ECVT data were acquired at a temporal resolution of 12.5 ms and a nominal spatial resolution of 2.5 mm × 2.5 mm × 4.5 mm. Snapshot MR data were acquired at a temporal resolution of 26 ms and a spatial resolution of 1.9 mm × 1.9 mm in the transverse plane and 1.9 mm × 3.8 mm in the axial plane. The particles were doped with water to produce a detectable signal with MR. The two techniques are demonstrated to produce quantitatively comparable time-averaged measurements of the voidage. The bubble frequencies measured from the snapshot images using both techniques were found to be in good agreement. However, the signal intensity inside the gas bubbles was more accurate when measured with MR, and the wake structure could be more clearly resolved using MR. This was attributed to the effect of the smoothing, or point spread function, of the ECVT measurements. An initial estimate of the smoothing in the ECVT has been performed by assuming a Gaussian point spread function. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002073 [article] Comparison of ECVT and MR measurements of voidage in a gas-fluidized bed [texte imprimé] / D. J. Holland, Éditeur scientifique ; Q. Marashdeh, Éditeur scientifique ; C. R. Müller, Éditeur scientifique . - 2009 . - p. 172-181. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 172-181 Mots-clés : Magnetic resonance (MR) Electrical capacitance volume tomography (ECVT) Gas-fluidized Résumé : This paper reports the first quantitative comparison of magnetic resonance (MR) and electrical capacitance volume tomography (ECVT) on a 50 mm diameter gas-fluidized bed of silica−alumina catalyst support particles (dp = 58 μm). ECVT data were acquired at a temporal resolution of 12.5 ms and a nominal spatial resolution of 2.5 mm × 2.5 mm × 4.5 mm. Snapshot MR data were acquired at a temporal resolution of 26 ms and a spatial resolution of 1.9 mm × 1.9 mm in the transverse plane and 1.9 mm × 3.8 mm in the axial plane. The particles were doped with water to produce a detectable signal with MR. The two techniques are demonstrated to produce quantitatively comparable time-averaged measurements of the voidage. The bubble frequencies measured from the snapshot images using both techniques were found to be in good agreement. However, the signal intensity inside the gas bubbles was more accurate when measured with MR, and the wake structure could be more clearly resolved using MR. This was attributed to the effect of the smoothing, or point spread function, of the ECVT measurements. An initial estimate of the smoothing in the ECVT has been performed by assuming a Gaussian point spread function. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002073

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Voidage at the layer inversion point in binary-solid liquid-fluidized beds / Renaud Escudié in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 182-184 Titre : Voidage at the layer inversion point in binary-solid liquid-fluidized beds Type de document : texte imprimé Auteurs : Renaud Escudié, Éditeur scientifique ; Norman Epstein, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 182-184 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid Liquid-Fluidized Layer-inversion phenomenon voidage Résumé : On the basis of three well documented runs on the layer-inversion phenomenon in binary liquid-fluidized beds, it is shown that the best method, to date, for predicting the layer-inversion voidage, knowing the layer inversion velocity, is via the bed contraction equation of Westman (1936), with the adjustable parameter G of that equation as recently modeled. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800246j [article] Voidage at the layer inversion point in binary-solid liquid-fluidized beds [texte imprimé] / Renaud Escudié, Éditeur scientifique ; Norman Epstein, Éditeur scientifique . - 2009 . - p. 182-184. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 182-184 Mots-clés : Solid Liquid-Fluidized Layer-inversion phenomenon voidage Résumé : On the basis of three well documented runs on the layer-inversion phenomenon in binary liquid-fluidized beds, it is shown that the best method, to date, for predicting the layer-inversion voidage, knowing the layer inversion velocity, is via the bed contraction equation of Westman (1936), with the adjustable parameter G of that equation as recently modeled. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800246j

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Electrostatics generation in a small cyclone separator / Zhongxiang Chen in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 185-190 Titre : Electrostatics generation in a small cyclone separator Type de document : texte imprimé Auteurs : Zhongxiang Chen, Éditeur scientifique ; Hsiaotao T. Bi, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 185-190 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrostatics Résumé : Experiments were conducted in a small cyclone separator (50 mm inner diameter) with two grades of commercial polyethylene particles, to study the electrostatic charge generation during the gas−solid transportation and separation. Results show clearly that the charges generated in the cyclone test unit were quite reproducible. When solid particles were fed to the cyclone, there was an abrupt change in the current flow and a quick increase of (negative) charge generation for both types of polyethylene particles. Both the charge density and the charge generation rate were always higher for the particles of higher density and smaller mean size. For both types of polyethylene, the (negative) charge density increased almost linearly with the gas velocity. When the solid feed rate or initial solid loading increased, the magnitude of the charge density decreased because there were fewer particle−wall collisions at higher solids feeding rate or higher solids concentration, due to shielding effects. Results indicate that the pipe section contributed En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071502p [article] Electrostatics generation in a small cyclone separator [texte imprimé] / Zhongxiang Chen, Éditeur scientifique ; Hsiaotao T. Bi, Éditeur scientifique . - 2009 . - p. 185-190. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 185-190 Mots-clés : Electrostatics Résumé : Experiments were conducted in a small cyclone separator (50 mm inner diameter) with two grades of commercial polyethylene particles, to study the electrostatic charge generation during the gas−solid transportation and separation. Results show clearly that the charges generated in the cyclone test unit were quite reproducible. When solid particles were fed to the cyclone, there was an abrupt change in the current flow and a quick increase of (negative) charge generation for both types of polyethylene particles. Both the charge density and the charge generation rate were always higher for the particles of higher density and smaller mean size. For both types of polyethylene, the (negative) charge density increased almost linearly with the gas velocity. When the solid feed rate or initial solid loading increased, the magnitude of the charge density decreased because there were fewer particle−wall collisions at higher solids feeding rate or higher solids concentration, due to shielding effects. Results indicate that the pipe section contributed En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071502p

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Removal of oil from water by inverse fluidization of aerogels / Jose A. Quevedo in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 191-201 Titre : Removal of oil from water by inverse fluidization of aerogels Type de document : texte imprimé Auteurs : Jose A. Quevedo, Éditeur scientifique ; Gaurav Patel, Éditeur scientifique ; Robert Pfeffer, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 191-201 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Removal of oil water Hydrophobic aerogel (Nanogel) Résumé : Surface-treated hydrophobic aerogel (Nanogel) granules of sizes between 500 and 850 μm, 1.7 and 2.3 mm, and 0.5 and 2.3 mm are fluidized by a downward flow of oil-contaminated water in an inverse fluidization mode. Aerogel particles are nanostructured, extremely light and porous, have a very large surface area per unit mass, and are sufficiently robust to be fluidized. Their hydrophobic surface gives them a strong affinity for oil and other organic compounds, with the exclusion of water. These desirable properties make them an ideal sorbent or filter media for the removal of oil from wastewater. The hydrodynamic characteristics of inverse fluidized beds of aerogel granules of different size ranges were studied by measuring the pressure drop and bed expansion as a function of superficial velocity. The oil removal efficiency and capacity of the aerogel granules in the inverse fluidized bed were found to depend mainly on the size of the granules, the initial height of the bed (amount of powder used), the void fraction, and the fluid velocity. Among the advantages of the process are the extremely low energy consumption (low pressure drop) during oil removal and the large absorption capacity. Oil concentrations of about 2000 mg/L in water could be reduced to less than 10 mg/L by the inverse fluidization process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800022e [article] Removal of oil from water by inverse fluidization of aerogels [texte imprimé] / Jose A. Quevedo, Éditeur scientifique ; Gaurav Patel, Éditeur scientifique ; Robert Pfeffer, Éditeur scientifique . - 2009 . - p. 191-201. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 191-201 Mots-clés : Removal of oil water Hydrophobic aerogel (Nanogel) Résumé : Surface-treated hydrophobic aerogel (Nanogel) granules of sizes between 500 and 850 μm, 1.7 and 2.3 mm, and 0.5 and 2.3 mm are fluidized by a downward flow of oil-contaminated water in an inverse fluidization mode. Aerogel particles are nanostructured, extremely light and porous, have a very large surface area per unit mass, and are sufficiently robust to be fluidized. Their hydrophobic surface gives them a strong affinity for oil and other organic compounds, with the exclusion of water. These desirable properties make them an ideal sorbent or filter media for the removal of oil from wastewater. The hydrodynamic characteristics of inverse fluidized beds of aerogel granules of different size ranges were studied by measuring the pressure drop and bed expansion as a function of superficial velocity. The oil removal efficiency and capacity of the aerogel granules in the inverse fluidized bed were found to depend mainly on the size of the granules, the initial height of the bed (amount of powder used), the void fraction, and the fluid velocity. Among the advantages of the process are the extremely low energy consumption (low pressure drop) during oil removal and the large absorption capacity. Oil concentrations of about 2000 mg/L in water could be reduced to less than 10 mg/L by the inverse fluidization process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800022e

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Simulations of structures in packed columns and validation by X-ray tomography / R. Caulkin in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 202-213 Titre : Simulations of structures in packed columns and validation by X-ray tomography Type de document : texte imprimé Auteurs : R. Caulkin, Éditeur scientifique ; X. Jia, Éditeur scientifique ; C. Xu, Éditeur scientifique Année de publication : 2009 Article en page(s) : p. 202-213 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : X-ray tomography computerized (CT) Résumé : Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray computerized tomography (CT). Two modified versions of what was previously a purely geometrical, digitally based packing algorithm were implemented. Both are aimed at incorporating the effects of particle interaction forces, one utilizing the distinct element method (DigiDEM) and the other an intermediate solution (collision-guided packing or DigiCGP). This article summarizes the models and the simulations performed using these two modified versions of DigiPac and, for model validation purposes, compares the predicted results with the corresponding X-ray tomographic scans of packed columns, in terms of bulk density, local packing density profiles, and pellet orientation distributions. For packed beds of relatively large and identical pellets, the simulation results indicate that particle−particle and particle−wall interactions cannot be ignored if realistic packing structures are to be obtained by simulation and even a simplistic treatment of these interactions can produce significantly more realistic packing structure than none at all. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800033a [article] Simulations of structures in packed columns and validation by X-ray tomography [texte imprimé] / R. Caulkin, Éditeur scientifique ; X. Jia, Éditeur scientifique ; C. Xu, Éditeur scientifique . - 2009 . - p. 202-213. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 202-213 Mots-clés : X-ray tomography computerized (CT) Résumé : Packing simulations of generic, nonspherical pellets were performed and compared with experimental data sets obtained using X-ray computerized tomography (CT). Two modified versions of what was previously a purely geometrical, digitally based packing algorithm were implemented. Both are aimed at incorporating the effects of particle interaction forces, one utilizing the distinct element method (DigiDEM) and the other an intermediate solution (collision-guided packing or DigiCGP). This article summarizes the models and the simulations performed using these two modified versions of DigiPac and, for model validation purposes, compares the predicted results with the corresponding X-ray tomographic scans of packed columns, in terms of bulk density, local packing density profiles, and pellet orientation distributions. For packed beds of relatively large and identical pellets, the simulation results indicate that particle−particle and particle−wall interactions cannot be ignored if realistic packing structures are to be obtained by simulation and even a simplistic treatment of these interactions can produce significantly more realistic packing structure than none at all. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800033a

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Modelling of multiphase flow in ironmaking blast furnace / X. F. Dong in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 214-226 Titre : Modelling of multiphase flow in ironmaking blast furnace Type de document : texte imprimé Auteurs : X. F. Dong, Éditeur scientifique ; A. B. Yu, Éditeur scientifique ; J. M. Burgess, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 214-226 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Multiphase flow Ironmaking blast furnace Résumé : A mathematical model for the four-phase (gas, powder, liquid, and solids) flow in a two-dimensional ironmaking blast furnace is presented by extending the existing two-fluid flow models. The model describes the motion of gas, solid, and powder phases, based on the continuum approach, and implements the so-called force balance model for the flow of liquids, such as metal and slag in a blast furnace. The model results demonstrate a solid stagnant zone and dense powder hold-up region, as well as a dense liquid flow region that exists in the lower part of a blast furnace, which are consistent with the experimental observations reported in the literature. The simulation is extended to investigate the effects of packing properties and operational conditions on the flow and the volume fraction distribution of each phase in a blast furnace. It is found that solid movement has a significant effect on powder holdup distribution. Small solid particles and low porosity distribution are predicted to affect the fluid flow considerably, and this can cause deterioration in bed permeability. The dynamic powder holdup in a furnace increases significantly with the increase of powder diameter. The findings should be useful to better understand and control blast furnace operations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800147v [article] Modelling of multiphase flow in ironmaking blast furnace [texte imprimé] / X. F. Dong, Éditeur scientifique ; A. B. Yu, Éditeur scientifique ; J. M. Burgess, Éditeur scientifique . - 2009 . - P. 214-226. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 214-226 Mots-clés : Multiphase flow Ironmaking blast furnace Résumé : A mathematical model for the four-phase (gas, powder, liquid, and solids) flow in a two-dimensional ironmaking blast furnace is presented by extending the existing two-fluid flow models. The model describes the motion of gas, solid, and powder phases, based on the continuum approach, and implements the so-called force balance model for the flow of liquids, such as metal and slag in a blast furnace. The model results demonstrate a solid stagnant zone and dense powder hold-up region, as well as a dense liquid flow region that exists in the lower part of a blast furnace, which are consistent with the experimental observations reported in the literature. The simulation is extended to investigate the effects of packing properties and operational conditions on the flow and the volume fraction distribution of each phase in a blast furnace. It is found that solid movement has a significant effect on powder holdup distribution. Small solid particles and low porosity distribution are predicted to affect the fluid flow considerably, and this can cause deterioration in bed permeability. The dynamic powder holdup in a furnace increases significantly with the increase of powder diameter. The findings should be useful to better understand and control blast furnace operations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800147v

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Drag law for bidisperse gas-solid suspensions containing equally sized spheres / Xiaolong Yin in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 227-241 Titre : Drag law for bidisperse gas-solid suspensions containing equally sized spheres Type de document : texte imprimé Auteurs : Xiaolong Yin, Éditeur scientifique ; Sankaran Sundaresan, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 227-241 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas−  Solid Hard-sphere fluid Fluid−  particle relative velocities Résumé : In this study, we constructed from lattice-Boltzmann simulations a drag correlation for bidisperse gas−solid suspensions containing equally sized particles that are moving with different velocities relative to the interstitial fluid. Our analysis is limited to flows at low Reynolds numbers and high Stokes numbers, and the microstructure of the suspension is identical to that of a hard-sphere fluid. The Stokes drag forces acting on the two particle species are related to the fluid−particle relative velocities by a friction coefficient matrix, the off-diagonal components of which represent the particle−particle drag due to hydrodynamic interactions and were found to give important contributions to the net drag force. The off-diagonals exhibit a logarithmic dependence on the lubrication cutoff distance, a length scale on which the lubrication force between approaching particles begins to level off. In our simulations, the total particle volume fraction ϕ ranges from 0.1 to 0.4, and the volume fraction ratio ϕ1/ϕ2 ranges from 1:1 to 1:7. The results from these simulations are captured in explicit constitutive models, which can be readily generalized to multicomponent mixtures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800171p [article] Drag law for bidisperse gas-solid suspensions containing equally sized spheres [texte imprimé] / Xiaolong Yin, Éditeur scientifique ; Sankaran Sundaresan, Éditeur scientifique . - 2009 . - P. 227-241. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 227-241 Mots-clés : Gas−  Solid Hard-sphere fluid Fluid−  particle relative velocities Résumé : In this study, we constructed from lattice-Boltzmann simulations a drag correlation for bidisperse gas−solid suspensions containing equally sized particles that are moving with different velocities relative to the interstitial fluid. Our analysis is limited to flows at low Reynolds numbers and high Stokes numbers, and the microstructure of the suspension is identical to that of a hard-sphere fluid. The Stokes drag forces acting on the two particle species are related to the fluid−particle relative velocities by a friction coefficient matrix, the off-diagonal components of which represent the particle−particle drag due to hydrodynamic interactions and were found to give important contributions to the net drag force. The off-diagonals exhibit a logarithmic dependence on the lubrication cutoff distance, a length scale on which the lubrication force between approaching particles begins to level off. In our simulations, the total particle volume fraction ϕ ranges from 0.1 to 0.4, and the volume fraction ratio ϕ1/ϕ2 ranges from 1:1 to 1:7. The results from these simulations are captured in explicit constitutive models, which can be readily generalized to multicomponent mixtures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800171p

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A numerical study of taylor bubbles / Xiaozhen Lu in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 242-252 Titre : A numerical study of taylor bubbles Type de document : texte imprimé Auteurs : Xiaozhen Lu, Éditeur scientifique ; Andrea Prosperetti, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 242-252 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Taylor bubbles Axisymmetric Résumé : Some results of a computational study of axisymmetric Taylor bubbles rising in a vertical tube filled with a quiescent, upward- or downward-flowing liquid are presented. The computational method is based on a finite-volume discretization of the Navier−Stokes equations on a staggered grid. The interface is maintained sharp and is discretized using a set of marker points linked by cubic splines. Independent theoretical results and published data are used for its validation. The simulations illustrate the effect of the Morton and Eötvös numbers on several steady-state and time-dependent processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800201x [article] A numerical study of taylor bubbles [texte imprimé] / Xiaozhen Lu, Éditeur scientifique ; Andrea Prosperetti, Éditeur scientifique . - 2009 . - P. 242-252. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 242-252 Mots-clés : Taylor bubbles Axisymmetric Résumé : Some results of a computational study of axisymmetric Taylor bubbles rising in a vertical tube filled with a quiescent, upward- or downward-flowing liquid are presented. The computational method is based on a finite-volume discretization of the Navier−Stokes equations on a staggered grid. The interface is maintained sharp and is discretized using a set of marker points linked by cubic splines. Independent theoretical results and published data are used for its validation. The simulations illustrate the effect of the Morton and Eötvös numbers on several steady-state and time-dependent processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800201x

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Particle motion in CFB cyclones as observed By positron emission particle tracking / Chian W. Chan in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 253-261 Titre : Particle motion in CFB cyclones as observed By positron emission particle tracking Type de document : texte imprimé Auteurs : Chian W. Chan, Éditeur scientifique ; Jonathan P. K. Seville, Éditeur scientifique ; Xianfeng Fan, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 253-261 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Circulating fluidized CFB Cyclones Résumé : Circulating fluidized bed (CFB) cyclones operate at high solids loadings. The paper presents, for the first time, particle trajectories within a cyclone obtained by positron emission particle tracking (PEPT), as a function of the solids loading (Cs). The pressure drop across a cyclone is a strong function of the solids loading. The objective of this work was to explain this behavior by direct observation of the particle movement. Cyclones normally operate in a stable particle movement mode, always with a spiral motion in the cylindrical part of the cyclone, followed by either a continued spiral in the cone (at low Cs) or by a much denser solids flow near the cone wall at higher Cs values. Data are used to obtain the tangential and axial velocity components of a tracer particle, the residence time of the particles in the cyclone, the thickness of the boundary layer in the cylindrical section of the cyclone, and the thickness of the dense wall layer in the conical section. This downward moving layer reduces the effective “free” cross section of the cyclone, thus increasing the air velocity and the pressure drop (ΔP), especially for small cyclones, as in the present research. This effect will be negligible for larger cyclones, where the influence of solids film thickness is less important, when compared to cyclone diameter, and ΔP values are expected to remain almost constant with increases in the solids loading. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800213g [article] Particle motion in CFB cyclones as observed By positron emission particle tracking [texte imprimé] / Chian W. Chan, Éditeur scientifique ; Jonathan P. K. Seville, Éditeur scientifique ; Xianfeng Fan, Éditeur scientifique . - 2009 . - P. 253-261. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 253-261 Mots-clés : Circulating fluidized CFB Cyclones Résumé : Circulating fluidized bed (CFB) cyclones operate at high solids loadings. The paper presents, for the first time, particle trajectories within a cyclone obtained by positron emission particle tracking (PEPT), as a function of the solids loading (Cs). The pressure drop across a cyclone is a strong function of the solids loading. The objective of this work was to explain this behavior by direct observation of the particle movement. Cyclones normally operate in a stable particle movement mode, always with a spiral motion in the cylindrical part of the cyclone, followed by either a continued spiral in the cone (at low Cs) or by a much denser solids flow near the cone wall at higher Cs values. Data are used to obtain the tangential and axial velocity components of a tracer particle, the residence time of the particles in the cyclone, the thickness of the boundary layer in the cylindrical section of the cyclone, and the thickness of the dense wall layer in the conical section. This downward moving layer reduces the effective “free” cross section of the cyclone, thus increasing the air velocity and the pressure drop (ΔP), especially for small cyclones, as in the present research. This effect will be negligible for larger cyclones, where the influence of solids film thickness is less important, when compared to cyclone diameter, and ΔP values are expected to remain almost constant with increases in the solids loading. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800213g

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Solution of bivariate population balance equations using the finite size domain complete set of trial functions method of moments (FCMOM) / Matteo Strumendo in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 262-273 Titre : Solution of bivariate population balance equations using the finite size domain complete set of trial functions method of moments (FCMOM) Type de document : texte imprimé Auteurs : Matteo Strumendo, Éditeur scientifique ; Hamid Arastoopour, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 262-273 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : FCMOM (Finite size domain Complete set of trial functions Method Of Moments) Résumé : The FCMOM (Finite size domain Complete set of trial functions Method Of Moments) is an efficient and accurate numerical technique to solve PBE (population balance equations) and was validated for monovariate PBE [Strumendo, M.; Arastoopour, H. Solution of PBE by MOM in Finite Size Domains. Chem. Eng. Sci. 2008, 63 (10), 2624]. In the present paper, the FCMOM is extended and used to solve bivariate PBE. In the FCMOM, the method of moments is formulated in a finite domain of the internal coordinates and the particle distribution function is represented as a truncated series expansion by a complete system of orthonormal functions. In the extension to bivariate PBE, the capabilities of the FCMOM are maintained, particularly as far as the algorithm efficiency and the accuracy in the bivariate particle distribution function reconstruction. The FCMOM was validated with the following bivariate applications: particle growth, particle dissolution, particle aggregation, and simultaneous aggregation and growth. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800272a [article] Solution of bivariate population balance equations using the finite size domain complete set of trial functions method of moments (FCMOM) [texte imprimé] / Matteo Strumendo, Éditeur scientifique ; Hamid Arastoopour, Éditeur scientifique . - 2009 . - P. 262-273. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 262-273 Mots-clés : FCMOM (Finite size domain Complete set of trial functions Method Of Moments) Résumé : The FCMOM (Finite size domain Complete set of trial functions Method Of Moments) is an efficient and accurate numerical technique to solve PBE (population balance equations) and was validated for monovariate PBE [Strumendo, M.; Arastoopour, H. Solution of PBE by MOM in Finite Size Domains. Chem. Eng. Sci. 2008, 63 (10), 2624]. In the present paper, the FCMOM is extended and used to solve bivariate PBE. In the FCMOM, the method of moments is formulated in a finite domain of the internal coordinates and the particle distribution function is represented as a truncated series expansion by a complete system of orthonormal functions. In the extension to bivariate PBE, the capabilities of the FCMOM are maintained, particularly as far as the algorithm efficiency and the accuracy in the bivariate particle distribution function reconstruction. The FCMOM was validated with the following bivariate applications: particle growth, particle dissolution, particle aggregation, and simultaneous aggregation and growth. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800272a

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New calibration methods for accurate electrical capacitance tomography measurements in particulate-fluid systems / Hadi Bashar in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 274-280 Titre : New calibration methods for accurate electrical capacitance tomography measurements in particulate-fluid systems Type de document : texte imprimé Auteurs : Hadi Bashar, Éditeur scientifique ; Franco Berruti, Éditeur scientifique ; Cedric Briens, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 274-280 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Tomography measurements (ECT) Electrical capacitance Résumé : Three different calibration techniques have been developed to greatly improve the accuracy of the solid holdup distributions obtained from electrical capacitance tomography (ECT) measurements. First, liquid mixtures are used to calibrate the ECT system. Second, the relative permittivity of solid particles is obtained by immersing the solids in different fluids: the solid relative permittivity corresponds to the point where the fluid relative permittivity matches the relative permittivity of the liquid−solid mixture. Third, the best relationship between solid holdup and electrical permittivity, over the required range of solid concentrations, is determined, for each particulate system, by suspending the particles in a viscous liquid honey. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800292d [article] New calibration methods for accurate electrical capacitance tomography measurements in particulate-fluid systems [texte imprimé] / Hadi Bashar, Éditeur scientifique ; Franco Berruti, Éditeur scientifique ; Cedric Briens, Éditeur scientifique . - 2009 . - P. 274-280. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 274-280 Mots-clés : Tomography measurements (ECT) Electrical capacitance Résumé : Three different calibration techniques have been developed to greatly improve the accuracy of the solid holdup distributions obtained from electrical capacitance tomography (ECT) measurements. First, liquid mixtures are used to calibrate the ECT system. Second, the relative permittivity of solid particles is obtained by immersing the solids in different fluids: the solid relative permittivity corresponds to the point where the fluid relative permittivity matches the relative permittivity of the liquid−solid mixture. Third, the best relationship between solid holdup and electrical permittivity, over the required range of solid concentrations, is determined, for each particulate system, by suspending the particles in a viscous liquid honey. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800292d

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Radial distributions of phase holdups and phase propagation velocities in a three-phase gas-liquid-solid fluidized bed (GLSCFB) riser / S. A. Razzak in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 281-289 Titre : Radial distributions of phase holdups and phase propagation velocities in a three-phase gas-liquid-solid fluidized bed (GLSCFB) riser Type de document : texte imprimé Auteurs : S. A. Razzak, Éditeur scientifique ; J.-X. Zhu, Éditeur scientifique ; S. Barghi, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 281-289 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Radial Distributions Gas−  Liquid−  Solid Fluidized Bed Résumé : Electrical resistance tomography (ERT) and fiber optic were applied to investigate phase holdups and phase propagation velocities in a gas−liquid−solid circulating fluidized bed (GLSCFB). Since ERT is applicable only to conductive phase(s), e.g. the liquid phase in this study, a fiber optic probe was employed simultaneously to quantify all three phases. Saline water was used as the conductive and continuous phase. Glass beads and lava rocks constitute the solid phase and air as the gas phase. Glass beads were transparent and spherical in shape; however, lava rock particles were irregular in shape and opaque, which affected the signals obtained from the optical fiber probe. An empirical model was developed to measure the gas holdup using optical fiber probe data. Gas holdup was higher in the central region and decreased radially, while opposite trend was observed with solid holdup due to the drag forces imposed on solid particles by the gas and liquid flow in the riser. By applying cross-correlation between the data obtained at two different levels in the riser, nonconductive phase propagation velocity was obtained. The propagation velocity was higher in the central region compared to the wall region and increased with increasing liquid superficial velocity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800299w [article] Radial distributions of phase holdups and phase propagation velocities in a three-phase gas-liquid-solid fluidized bed (GLSCFB) riser [texte imprimé] / S. A. Razzak, Éditeur scientifique ; J.-X. Zhu, Éditeur scientifique ; S. Barghi, Éditeur scientifique . - 2009 . - P. 281-289. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 281-289 Mots-clés : Radial Distributions Gas−  Liquid−  Solid Fluidized Bed Résumé : Electrical resistance tomography (ERT) and fiber optic were applied to investigate phase holdups and phase propagation velocities in a gas−liquid−solid circulating fluidized bed (GLSCFB). Since ERT is applicable only to conductive phase(s), e.g. the liquid phase in this study, a fiber optic probe was employed simultaneously to quantify all three phases. Saline water was used as the conductive and continuous phase. Glass beads and lava rocks constitute the solid phase and air as the gas phase. Glass beads were transparent and spherical in shape; however, lava rock particles were irregular in shape and opaque, which affected the signals obtained from the optical fiber probe. An empirical model was developed to measure the gas holdup using optical fiber probe data. Gas holdup was higher in the central region and decreased radially, while opposite trend was observed with solid holdup due to the drag forces imposed on solid particles by the gas and liquid flow in the riser. By applying cross-correlation between the data obtained at two different levels in the riser, nonconductive phase propagation velocity was obtained. The propagation velocity was higher in the central region compared to the wall region and increased with increasing liquid superficial velocity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800299w

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Modeling of regime transition in bubble columns with stability condition / Jianhua Chen in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 290-301 Titre : Modeling of regime transition in bubble columns with stability condition Type de document : texte imprimé Auteurs : Jianhua Chen, Éditeur scientifique ; Ning Yang, Éditeur scientifique ; Wei Ge, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 290-301 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Regime Transition Hydrodynamique Dual-bubble-size (DBS) Résumé : Understanding the physical essence of regime transition is of crucial importance for the modeling and simulation of hydrodynamics and heat and mass transfer in bubble columns. The regime transition of the air−water system has been captured by the dual-bubble-size (DBS) model in our previous work [Yang et al. Chem. Eng. Sci. 2007, 62, 6978−6991] as a jump change from one minimum point of the stability criterion to the other. The DBS model features the incorporation of a stability condition with hydrodynamic conservation equations through the analysis of compromise between dominant mechanisms. This work reiterates our previous work and further explores some remaining issues and underlying physics related to the jump change by analyzing the trajectory of global minimum points in the three-dimensional space of structural parameters. The influence of drag coefficient correlations on the model prediction is investigated. The effect of liquid viscosity on regime transition is evaluated using the DBS model for saccharose and glycerin systems. The dual effects of liquid viscosity reported in literature, namely, suppressing the regime transition while slightly increasing viscosity and destabilizing the homogeneous regime at higher viscosity, can be reasonably predicted with this model. Finally, the concept of the compromise between dominant mechanisms is extended to understand the bubble behavior at different scales and its relationship with stability condition. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003623 [article] Modeling of regime transition in bubble columns with stability condition [texte imprimé] / Jianhua Chen, Éditeur scientifique ; Ning Yang, Éditeur scientifique ; Wei Ge, Éditeur scientifique . - 2009 . - P. 290-301. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 290-301 Mots-clés : Regime Transition Hydrodynamique Dual-bubble-size (DBS) Résumé : Understanding the physical essence of regime transition is of crucial importance for the modeling and simulation of hydrodynamics and heat and mass transfer in bubble columns. The regime transition of the air−water system has been captured by the dual-bubble-size (DBS) model in our previous work [Yang et al. Chem. Eng. Sci. 2007, 62, 6978−6991] as a jump change from one minimum point of the stability criterion to the other. The DBS model features the incorporation of a stability condition with hydrodynamic conservation equations through the analysis of compromise between dominant mechanisms. This work reiterates our previous work and further explores some remaining issues and underlying physics related to the jump change by analyzing the trajectory of global minimum points in the three-dimensional space of structural parameters. The influence of drag coefficient correlations on the model prediction is investigated. The effect of liquid viscosity on regime transition is evaluated using the DBS model for saccharose and glycerin systems. The dual effects of liquid viscosity reported in literature, namely, suppressing the regime transition while slightly increasing viscosity and destabilizing the homogeneous regime at higher viscosity, can be reasonably predicted with this model. Finally, the concept of the compromise between dominant mechanisms is extended to understand the bubble behavior at different scales and its relationship with stability condition. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003623

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Improved drying in a pulsation-assisted fluidized bed / Ali Akhavan in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 302-309 Titre : Improved drying in a pulsation-assisted fluidized bed Type de document : texte imprimé Auteurs : Ali Akhavan, Éditeur scientifique ; J. Ruud van Ommen, Éditeur scientifique ; John Nijenhuis, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 302-309 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pulsation-assisted fluidized Gas flow Résumé : Gas flow pulsation was employed to improve the drying of porous pharmaceutical granules in a cylindrical fluidized bed. In our approach, a fraction of the total flow was oscillating intermittently and periodically, typically at 3 Hz during 2 min and remaining constant during the other 2 min of each 4 min cycle. It was found that such pulsation-assisted fluidization not only shortened the total drying time but also enhanced homogeneity. A transition in fluidization behavior, reflected by a distinct transition in the bed dominant frequencies, was observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800458h [article] Improved drying in a pulsation-assisted fluidized bed [texte imprimé] / Ali Akhavan, Éditeur scientifique ; J. Ruud van Ommen, Éditeur scientifique ; John Nijenhuis, Éditeur scientifique . - 2009 . - P. 302-309. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 302-309 Mots-clés : Pulsation-assisted fluidized Gas flow Résumé : Gas flow pulsation was employed to improve the drying of porous pharmaceutical granules in a cylindrical fluidized bed. In our approach, a fraction of the total flow was oscillating intermittently and periodically, typically at 3 Hz during 2 min and remaining constant during the other 2 min of each 4 min cycle. It was found that such pulsation-assisted fluidization not only shortened the total drying time but also enhanced homogeneity. A transition in fluidization behavior, reflected by a distinct transition in the bed dominant frequencies, was observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800458h

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Entrance effects on gas-solid riser flow structure / Jun You in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 310-319 Titre : Entrance effects on gas-solid riser flow structure Type de document : texte imprimé Auteurs : Jun You, Éditeur scientifique ; Dawei Wang, Éditeur scientifique ; Chao Zhu, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 310-319 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-Solid Flow structure dynamics Résumé : The gas−solid flow in a riser has strong inherent nonuniformities both in the flow structure and in the dynamic phases. The flow structure in a riser can be altered with the implementation of different solids feeding devices, and hence may affect the reactor performance. This paper is aimed at investigating the effect of various riser entrances on the overall flow structure and its stability at different operation conditions. Three riser entrances are selected to simulate the common solids feeding devices of risers, namely, the J-bend feeder, the L-valve feeder with a distributor, and the L-valve feeder after a taper section. The study is first focused on the flow dynamics in the riser entrance region. This is to identify the characteristic height of the entrance region as well as to obtain the radial distributions of phase transport properties at the end of the entrance region. These radial profiles are then used as the flow inlet conditions in the mechanistic model for the study of overall flow structure and stability in the riser main region. The study shows that the flow structure in the entrance region can be strongly affected by the selection of solids feeding patterns but weakly dependent upon the operation conditions. The flow structure in the main riser region, however, is weakly dependent upon the selection of solids feeding patterns but strongly affected by the operation conditions. The riser characteristic length of the entrance region is nearly independent of the gas inlet velocity and solids mass flow rate; however, it is moderately influenced by the solid feeding pattern. As part of model validation, some simulation results are directly compared with available experimental measurements, with reasonably good agreement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004868 [article] Entrance effects on gas-solid riser flow structure [texte imprimé] / Jun You, Éditeur scientifique ; Dawei Wang, Éditeur scientifique ; Chao Zhu, Éditeur scientifique . - 2009 . - P. 310-319. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 310-319 Mots-clés : Gas-Solid Flow structure dynamics Résumé : The gas−solid flow in a riser has strong inherent nonuniformities both in the flow structure and in the dynamic phases. The flow structure in a riser can be altered with the implementation of different solids feeding devices, and hence may affect the reactor performance. This paper is aimed at investigating the effect of various riser entrances on the overall flow structure and its stability at different operation conditions. Three riser entrances are selected to simulate the common solids feeding devices of risers, namely, the J-bend feeder, the L-valve feeder with a distributor, and the L-valve feeder after a taper section. The study is first focused on the flow dynamics in the riser entrance region. This is to identify the characteristic height of the entrance region as well as to obtain the radial distributions of phase transport properties at the end of the entrance region. These radial profiles are then used as the flow inlet conditions in the mechanistic model for the study of overall flow structure and stability in the riser main region. The study shows that the flow structure in the entrance region can be strongly affected by the selection of solids feeding patterns but weakly dependent upon the operation conditions. The flow structure in the main riser region, however, is weakly dependent upon the selection of solids feeding patterns but strongly affected by the operation conditions. The riser characteristic length of the entrance region is nearly independent of the gas inlet velocity and solids mass flow rate; however, it is moderately influenced by the solid feeding pattern. As part of model validation, some simulation results are directly compared with available experimental measurements, with reasonably good agreement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004868

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Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds / Wajeeh O. Moughrabiah in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 320-325 Titre : Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds Type de document : texte imprimé Auteurs : Wajeeh O. Moughrabiah, Éditeur scientifique ; John R. Grace, Éditeur scientifique ; Xiaotao T. Bi, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 320-325 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Effects of Pressure Temperature Electrostatics Gas−  Solid Résumé : The influences of operating pressure, temperature, and gas velocity on the degree of electrification in a fluidized bed of glass beads and different grades of polyethylene resin were investigated in a fluidization column of 150-mm inner diameter and 2.0-m height. Eight collision ball probes at different levels and radial positions measured the degree of electrification in the bed. Faraday cups also measured the charge density in the bed by taking samples from three different online sampling ports at different levels. The degree of electrification increased as pressure increased from 1.0 to 8.0 bar, probably due to an increase in bubble rise velocity, frequency, and volume fraction. The maximum static charges were found at approximately two-thirds of the bed height and near the axis. As the pressure increased, particle−particle and particle−wall collisions near the distributor and wall contributed heavily to static charge generation. At higher temperatures (up to 75 °C), the bed exhibited smoother fluidization. Temperature played a significant role in determining electrostatic charging. As the superficial gas velocity increased from 0.23 to 0.40 m/s, the degree of electrification increased. However, at higher gas velocities, the polarity in the freeboard region was opposite to that in the bed, indicating that fines entrained from the column carried charges, resulting in a net charge of polarity opposite to that inside the bed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800556y [article] Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds [texte imprimé] / Wajeeh O. Moughrabiah, Éditeur scientifique ; John R. Grace, Éditeur scientifique ; Xiaotao T. Bi, Éditeur scientifique . - 2009 . - P. 320-325. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 320-325 Mots-clés : Effects of Pressure Temperature Electrostatics Gas−  Solid Résumé : The influences of operating pressure, temperature, and gas velocity on the degree of electrification in a fluidized bed of glass beads and different grades of polyethylene resin were investigated in a fluidization column of 150-mm inner diameter and 2.0-m height. Eight collision ball probes at different levels and radial positions measured the degree of electrification in the bed. Faraday cups also measured the charge density in the bed by taking samples from three different online sampling ports at different levels. The degree of electrification increased as pressure increased from 1.0 to 8.0 bar, probably due to an increase in bubble rise velocity, frequency, and volume fraction. The maximum static charges were found at approximately two-thirds of the bed height and near the axis. As the pressure increased, particle−particle and particle−wall collisions near the distributor and wall contributed heavily to static charge generation. At higher temperatures (up to 75 °C), the bed exhibited smoother fluidization. Temperature played a significant role in determining electrostatic charging. As the superficial gas velocity increased from 0.23 to 0.40 m/s, the degree of electrification increased. However, at higher gas velocities, the polarity in the freeboard region was opposite to that in the bed, indicating that fines entrained from the column carried charges, resulting in a net charge of polarity opposite to that inside the bed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800556y

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Kinetic theory explanation of a circulating fluidized bed ring structure near choking / Mehmet Tartan in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 326-329 Titre : Kinetic theory explanation of a circulating fluidized bed ring structure near choking Type de document : texte imprimé Auteurs : Mehmet Tartan, Éditeur scientifique ; Dimitri Gidaspow, Éditeur scientifique ; Veeraya Jiradilok, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 326-329 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Kinetic theory Ring structure Fluidized catalytic cracking (FCC) Résumé : The objective of this technical note is to give an alternate explanation of the ring structure behavior for the flow of fluidized catalytic cracking (FCC) particles in a riser recently obtained in L. S. Fan’s laboratory. Their recent explanation of this phenomenon is due to the low velocity at the center. While indeed this is one of the causes of the high concentration near the center, we show that an additional driving force for the higher concentration at the center is the low granular temperature caused by the dissipation of random kinetic energy at the center of the riser. An approximate analytical solution applied to the flow of FCC particles obtained in Fan’s laboratory again produces a dip in the granular temperature in the center and hence a rise in the particle concentration. This phenomenon occurs as a result of the constancy of solids pressure in the developed region of the riser. It is the so-called shear-induced diffusion effect well-known for neutrally buoyant particles in liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007192 [article] Kinetic theory explanation of a circulating fluidized bed ring structure near choking [texte imprimé] / Mehmet Tartan, Éditeur scientifique ; Dimitri Gidaspow, Éditeur scientifique ; Veeraya Jiradilok, Éditeur scientifique . - 2009 . - P. 326-329. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 326-329 Mots-clés : Kinetic theory Ring structure Fluidized catalytic cracking (FCC) Résumé : The objective of this technical note is to give an alternate explanation of the ring structure behavior for the flow of fluidized catalytic cracking (FCC) particles in a riser recently obtained in L. S. Fan’s laboratory. Their recent explanation of this phenomenon is due to the low velocity at the center. While indeed this is one of the causes of the high concentration near the center, we show that an additional driving force for the higher concentration at the center is the low granular temperature caused by the dissipation of random kinetic energy at the center of the riser. An approximate analytical solution applied to the flow of FCC particles obtained in Fan’s laboratory again produces a dip in the granular temperature in the center and hence a rise in the particle concentration. This phenomenon occurs as a result of the constancy of solids pressure in the developed region of the riser. It is the so-called shear-induced diffusion effect well-known for neutrally buoyant particles in liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007192

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Analysis of hydrodynamics and microstructure in a bubble column by planar shadow image velocimetry / M. Sommerfeld in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 330-340 Titre : Analysis of hydrodynamics and microstructure in a bubble column by planar shadow image velocimetry Type de document : texte imprimé Auteurs : M. Sommerfeld, Éditeur scientifique ; D. Bröder, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 330-340 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrodynamics Microstructure PTV (particle tracking velocimetry) Résumé : The hydrodynamics and bubble behavior in a laboratory-scale bubble column (diameter 140 mm) was analyzed using planar shadow image velocimetry. Different air flow rates were considered by using capillary aerators with different capillary diameter. This implies that a gas hold-up between 1 and 5% and a bubble number mean diameter between about 2 and 4 mm was realized. The imaging system consists of a background illumination utilizing a LED-array and a single CCD-camera which records simultaneously bubble and tracer images. The demarcation of the thickness of the imaging plane was realized by using a macrolens adjusted to small depth of field. To discard out-of-focus images of bubbles and tracer particles and to discriminate between both phases different gradient filters were applied. A Sobel filter was used to evaluate the bubble contours in order to obtain the area equivalent diameter, the eccentricity, and the bubble orientation. The velocity fields of both phases and horizontal profiles along the bubble column were determined by applying PTV (particle tracking velocimetry) for the bubbles and PIV (particle imaging velocimetry) for the tracer particles. For both phases axial and radial mean velocities as well as their fluctuating components were determined by averaging a sufficient number of double images. From these results also cross-sectional averages and global averages of turbulent kinetic energy and fluctuation energy of the bubbles were determined. It was found that the bubble fluctuation in the radial direction was higher than in the axial one for bubble sizes in the range between about 2.0 and 3.8 mm which is a result of the zigzag or helical motion of the bubbles. Finally also the bubble behavior was further analyzed by determining bubble eccentricity and orientation of the bubbles in the flow. These data are especially useful for modeling bubble oscillation and tumbling motion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800838u [article] Analysis of hydrodynamics and microstructure in a bubble column by planar shadow image velocimetry [texte imprimé] / M. Sommerfeld, Éditeur scientifique ; D. Bröder, Éditeur scientifique . - 2009 . - P. 330-340. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 330-340 Mots-clés : Hydrodynamics Microstructure PTV (particle tracking velocimetry) Résumé : The hydrodynamics and bubble behavior in a laboratory-scale bubble column (diameter 140 mm) was analyzed using planar shadow image velocimetry. Different air flow rates were considered by using capillary aerators with different capillary diameter. This implies that a gas hold-up between 1 and 5% and a bubble number mean diameter between about 2 and 4 mm was realized. The imaging system consists of a background illumination utilizing a LED-array and a single CCD-camera which records simultaneously bubble and tracer images. The demarcation of the thickness of the imaging plane was realized by using a macrolens adjusted to small depth of field. To discard out-of-focus images of bubbles and tracer particles and to discriminate between both phases different gradient filters were applied. A Sobel filter was used to evaluate the bubble contours in order to obtain the area equivalent diameter, the eccentricity, and the bubble orientation. The velocity fields of both phases and horizontal profiles along the bubble column were determined by applying PTV (particle tracking velocimetry) for the bubbles and PIV (particle imaging velocimetry) for the tracer particles. For both phases axial and radial mean velocities as well as their fluctuating components were determined by averaging a sufficient number of double images. From these results also cross-sectional averages and global averages of turbulent kinetic energy and fluctuation energy of the bubbles were determined. It was found that the bubble fluctuation in the radial direction was higher than in the axial one for bubble sizes in the range between about 2.0 and 3.8 mm which is a result of the zigzag or helical motion of the bubbles. Finally also the bubble behavior was further analyzed by determining bubble eccentricity and orientation of the bubbles in the flow. These data are especially useful for modeling bubble oscillation and tumbling motion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800838u

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Exploratory design study on reactor configurations for carbon dioxide capture from conventional power plants employing regenerable solid sorbents / Wen-Ching Yang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 341-351 Titre : Exploratory design study on reactor configurations for carbon dioxide capture from conventional power plants employing regenerable solid sorbents Type de document : texte imprimé Auteurs : Wen-Ching Yang, Éditeur scientifique ; James Hoffman, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 341-351 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon dioxide Reactor configurations CO2 Résumé : Preliminary commercial designs were carried out for a fluidized bed as a CO2 adsorber and a moving bed as a regenerator. Reverse engineering methodology was employed on the basis of a commercial 500 MW supercritical PC power plant whereby the boundaries required for a particular reactor design and configuration could be set. Employing the proposed moving bed for regenerator is, however, not promising because of poor heat transfer, evolution of CO2 during regeneration, and high pressure drop when small particles are used. If regeneration kinetics is as slow as reported in tens of minutes, the bed height can be quite high and the reactor can be quite costly. In its place, a so-called assisted self-fluidization bed with embedded heat transfer surface was proposed. Theoretically, there is no reason why the fluidized bed cannot be successfully designed and operated both as an adsorber and a regenerator under proper adsorption and regeneration kinetics. Recent publications, where fluidized beds, circulating fluidized beds, or a combination of them were employed both as an adsorber and a regenerator, were cited. Staging may not be necessary employing the fluidized bed technology because of the capability to control reaction temperature at the optimum operating temperature through embedded heat transfer surface in the fluidized beds. Even if the staging is necessary, the implementation of staging in fluidized beds at ambient pressure and moderate temperature is relatively easy and with minimum cost penalty. Example designs are presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800172e [article] Exploratory design study on reactor configurations for carbon dioxide capture from conventional power plants employing regenerable solid sorbents [texte imprimé] / Wen-Ching Yang, Éditeur scientifique ; James Hoffman, Éditeur scientifique . - 2009 . - P. 341-351. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 341-351 Mots-clés : Carbon dioxide Reactor configurations CO2 Résumé : Preliminary commercial designs were carried out for a fluidized bed as a CO2 adsorber and a moving bed as a regenerator. Reverse engineering methodology was employed on the basis of a commercial 500 MW supercritical PC power plant whereby the boundaries required for a particular reactor design and configuration could be set. Employing the proposed moving bed for regenerator is, however, not promising because of poor heat transfer, evolution of CO2 during regeneration, and high pressure drop when small particles are used. If regeneration kinetics is as slow as reported in tens of minutes, the bed height can be quite high and the reactor can be quite costly. In its place, a so-called assisted self-fluidization bed with embedded heat transfer surface was proposed. Theoretically, there is no reason why the fluidized bed cannot be successfully designed and operated both as an adsorber and a regenerator under proper adsorption and regeneration kinetics. Recent publications, where fluidized beds, circulating fluidized beds, or a combination of them were employed both as an adsorber and a regenerator, were cited. Staging may not be necessary employing the fluidized bed technology because of the capability to control reaction temperature at the optimum operating temperature through embedded heat transfer surface in the fluidized beds. Even if the staging is necessary, the implementation of staging in fluidized beds at ambient pressure and moderate temperature is relatively easy and with minimum cost penalty. Example designs are presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800172e

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In situ synthesis of TiO2-functionalized metal nanoparticles / David M. King in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 352-360 Titre : In situ synthesis of TiO2-functionalized metal nanoparticles Type de document : texte imprimé Auteurs : David M. King, Éditeur scientifique ; Yun Zhou, Éditeur scientifique ; Louis F. Hakim, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 352-360 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Metal nanoparticles Atomic layer deposition (ALD) Gas-phase TiO2 ALD Résumé : The ability to prepare and functionalize passivated nanosized metal powders was demonstrated using TiO2 films that were deposited via atomic layer deposition (ALD). Metal nanopowders were synthesized from the dehydration and subsequent decomposition of bulk quantities of metal oxalates in a fluidized-bed reactor. The gas-phase TiO2 ALD coating process was used to passivate these particles in situ, which alleviated the need to expose the oxygen-sensitive materials to air. Metal oxalate size reduction was achieved using a cryogenic milling process that reduced the micrometer-sized oxalate feed powder and yielded metal nanopowders with an average primary diameter of ∼50 nm. The metal oxalates that have received the most attention are those of iron, nickel, cobalt, and copper. Al2O3-based ALD films have been deposited on each of these metals, whereas TiO2:metal nanocomposite powder research has been performed here and is the basis for this work. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800196h [article] In situ synthesis of TiO2-functionalized metal nanoparticles [texte imprimé] / David M. King, Éditeur scientifique ; Yun Zhou, Éditeur scientifique ; Louis F. Hakim, Éditeur scientifique . - 2009 . - P. 352-360. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 352-360 Mots-clés : Metal nanoparticles Atomic layer deposition (ALD) Gas-phase TiO2 ALD Résumé : The ability to prepare and functionalize passivated nanosized metal powders was demonstrated using TiO2 films that were deposited via atomic layer deposition (ALD). Metal nanopowders were synthesized from the dehydration and subsequent decomposition of bulk quantities of metal oxalates in a fluidized-bed reactor. The gas-phase TiO2 ALD coating process was used to passivate these particles in situ, which alleviated the need to expose the oxygen-sensitive materials to air. Metal oxalate size reduction was achieved using a cryogenic milling process that reduced the micrometer-sized oxalate feed powder and yielded metal nanopowders with an average primary diameter of ∼50 nm. The metal oxalates that have received the most attention are those of iron, nickel, cobalt, and copper. Al2O3-based ALD films have been deposited on each of these metals, whereas TiO2:metal nanocomposite powder research has been performed here and is the basis for this work. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800196h

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Development of biomass charcoal combustion heater for household utilization / Masayuki Horio in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 361-372 Titre : Development of biomass charcoal combustion heater for household utilization Type de document : texte imprimé Auteurs : Masayuki Horio, Éditeur scientifique ; Amit Suri, Éditeur scientifique ; Junji Asahara, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 361-372 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biomass Charcoal Thin bed cross-flow (TBCF) Résumé : In the present work a prototype powdered biomass charcoal fired heater with a heat output of 6 kW is designed and developed so that a new powdered charcoal market can be initiated to enhance greenhouse gas (GHG) reduction through massive biomass utilization. The combustion heater was designed based on the concept of charcoal combustion in a thin bed cross-flow (TBCF) mode, where a very thin uniform bed of charcoal is fixed by air flow on the wall of a cylindrical chamber with an air-penetrable wall. The distinct advantage of using such a thin bed cross-flow is low fuel inventory and good air−fuel contact, resulting in fast startup/shutdown and low CO emissions in the exhaust gases. Fundamental data for realizing such a combustion heater are presented, and the performance characterization of the thus manufactured heater is investigated. The combustion heater was characterized for charcoal prepared from Japanese oak (Quercus serrata) and from several waste biomass sources, such as a pruned apple branch and charcoal formed from spent coffee waste and soybean fiber. For wood charcoal the heater’s thermal efficiency was about 65−86%, and for waste biomass charcoal species it was found to be in the range of 60−81%. When the combustion heater was operated at the stable combustion mode, the CO concentration in the exhaust after the flue gas passed through catalyst was less than 5 ppm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006243 [article] Development of biomass charcoal combustion heater for household utilization [texte imprimé] / Masayuki Horio, Éditeur scientifique ; Amit Suri, Éditeur scientifique ; Junji Asahara, Éditeur scientifique . - 2009 . - P. 361-372. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 361-372 Mots-clés : Biomass Charcoal Thin bed cross-flow (TBCF) Résumé : In the present work a prototype powdered biomass charcoal fired heater with a heat output of 6 kW is designed and developed so that a new powdered charcoal market can be initiated to enhance greenhouse gas (GHG) reduction through massive biomass utilization. The combustion heater was designed based on the concept of charcoal combustion in a thin bed cross-flow (TBCF) mode, where a very thin uniform bed of charcoal is fixed by air flow on the wall of a cylindrical chamber with an air-penetrable wall. The distinct advantage of using such a thin bed cross-flow is low fuel inventory and good air−fuel contact, resulting in fast startup/shutdown and low CO emissions in the exhaust gases. Fundamental data for realizing such a combustion heater are presented, and the performance characterization of the thus manufactured heater is investigated. The combustion heater was characterized for charcoal prepared from Japanese oak (Quercus serrata) and from several waste biomass sources, such as a pruned apple branch and charcoal formed from spent coffee waste and soybean fiber. For wood charcoal the heater’s thermal efficiency was about 65−86%, and for waste biomass charcoal species it was found to be in the range of 60−81%. When the combustion heater was operated at the stable combustion mode, the CO concentration in the exhaust after the flue gas passed through catalyst was less than 5 ppm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006243

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Characteristics of solid residues obtained from hot-compressed-water treatment of woody biomass / Nobusuke Kobayashi in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 373-379 Titre : Characteristics of solid residues obtained from hot-compressed-water treatment of woody biomass Type de document : texte imprimé Auteurs : Nobusuke Kobayashi, Éditeur scientifique ; Nobuhiko Okada, Éditeur scientifique ; Ayumu Hirakawa, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 373-379 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hot-Compressed-Water Treatment Solid Residues Woody biomass Résumé : Hydrolysis experiment of woody biomass in hot compressed water (HCW) was conducted in a batch-type reactor and the characteristics of solid residue after the HCW hydrolysis treatment were measured to understand the hydrolysis mechanism of woody biomass. Woody slurry of Douglas fir was used in this HCW experiment. Reaction temperature was controlled from 423 to 523 K, and the reaction time was set at 1 min. After separation of solid residues from the hydrolysis liquid material, the solid residue characteristics, such as proximate and ultimate analysis, particle size distribution, particle shape, surface area, pore size distribution, chemical composition, and equilibrium moisture content ratio, were measured and then the decomposition mechanism of woody biomass in HCW was discussed. It was found that the solid residue characteristics yielded in HCW changed drastically depending on the reaction temperature. For example, cellulose crystallinity decreased with increasing reaction temperature, and the physical characteristics of solid residue, such as particle shape, particle diameter, and pore size distribution, also changed dramatically depending on the reaction temperature. The physical or chemical characteristic change in HCW was strongly related to the decomposition of components of woody biomass at that reaction temperature. Dehydration of woody components was one of the most important factors to understand physical characteristics during HCW treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800870k [article] Characteristics of solid residues obtained from hot-compressed-water treatment of woody biomass [texte imprimé] / Nobusuke Kobayashi, Éditeur scientifique ; Nobuhiko Okada, Éditeur scientifique ; Ayumu Hirakawa, Éditeur scientifique . - 2009 . - P. 373-379. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 373-379 Mots-clés : Hot-Compressed-Water Treatment Solid Residues Woody biomass Résumé : Hydrolysis experiment of woody biomass in hot compressed water (HCW) was conducted in a batch-type reactor and the characteristics of solid residue after the HCW hydrolysis treatment were measured to understand the hydrolysis mechanism of woody biomass. Woody slurry of Douglas fir was used in this HCW experiment. Reaction temperature was controlled from 423 to 523 K, and the reaction time was set at 1 min. After separation of solid residues from the hydrolysis liquid material, the solid residue characteristics, such as proximate and ultimate analysis, particle size distribution, particle shape, surface area, pore size distribution, chemical composition, and equilibrium moisture content ratio, were measured and then the decomposition mechanism of woody biomass in HCW was discussed. It was found that the solid residue characteristics yielded in HCW changed drastically depending on the reaction temperature. For example, cellulose crystallinity decreased with increasing reaction temperature, and the physical characteristics of solid residue, such as particle shape, particle diameter, and pore size distribution, also changed dramatically depending on the reaction temperature. The physical or chemical characteristic change in HCW was strongly related to the decomposition of components of woody biomass at that reaction temperature. Dehydration of woody components was one of the most important factors to understand physical characteristics during HCW treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800870k

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Thermogravimetric analysis of copper oxide for chemical-looping hydrogen generation / Sung Real Son in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 380-387 Titre : Thermogravimetric analysis of copper oxide for chemical-looping hydrogen generation Type de document : texte imprimé Auteurs : Sung Real Son, Éditeur scientifique ; Kang Seok Go, Éditeur scientifique ; Sang Done Kim, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 380-387 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Thermogravimetric Copper Oxide Chemical-Looping Metal oxide Résumé : The chemical-looping hydrogen generation (CLH) system consists of reduction of metal oxide and water decomposition by oxidizing reduced metal oxide. In the present study, water decomposition by the reduction and oxidation of metal oxide (CuO) was conducted in a thermogravimetric analysis (TGA) system for the CLH process. The particles are reduced completely in an atmosphere of synthesis gas (H2 + CO), and the fully reduced particles decompose water to produce 3.7 L of H2 per kilogram of metal oxide. The particles prepared by the impregnation exhibits better reactivity than those by coprecipitation and the solid phase method, and the particles supported on Al2O3 exhibit better reactivity than those on SiO2. Based on the TGA, the reduction and oxidation of CuO/Al2O3 prepared via impregnation are characterized by the kinetic equations from the solid-state reaction rate models. The phase-controlled-boundary model was successfully applied to predict the initial stages of reduction and oxidation of the metal oxide, and the activation energies for reduction and oxidation are determined to be 4.13−19.5 and −55.8 kJ/mol, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800174c [article] Thermogravimetric analysis of copper oxide for chemical-looping hydrogen generation [texte imprimé] / Sung Real Son, Éditeur scientifique ; Kang Seok Go, Éditeur scientifique ; Sang Done Kim, Éditeur scientifique . - 2009 . - P. 380-387. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 380-387 Mots-clés : Thermogravimetric Copper Oxide Chemical-Looping Metal oxide Résumé : The chemical-looping hydrogen generation (CLH) system consists of reduction of metal oxide and water decomposition by oxidizing reduced metal oxide. In the present study, water decomposition by the reduction and oxidation of metal oxide (CuO) was conducted in a thermogravimetric analysis (TGA) system for the CLH process. The particles are reduced completely in an atmosphere of synthesis gas (H2 + CO), and the fully reduced particles decompose water to produce 3.7 L of H2 per kilogram of metal oxide. The particles prepared by the impregnation exhibits better reactivity than those by coprecipitation and the solid phase method, and the particles supported on Al2O3 exhibit better reactivity than those on SiO2. Based on the TGA, the reduction and oxidation of CuO/Al2O3 prepared via impregnation are characterized by the kinetic equations from the solid-state reaction rate models. The phase-controlled-boundary model was successfully applied to predict the initial stages of reduction and oxidation of the metal oxide, and the activation energies for reduction and oxidation are determined to be 4.13−19.5 and −55.8 kJ/mol, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800174c

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Ion-exchange resins / Spiro D. Alexandratos in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 388-398 Titre : Ion-exchange resins : a retrospective from industrial and engineering chemistry research Type de document : texte imprimé Auteurs : Spiro D. Alexandratos, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 388-398 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chemistry Research Wastewater treatment Hydrometallurgy Chromatography Résumé : Ion-exchange resins comprise one of the most important scientific developments of the 20th century. Their applicability to water softening, environmental remediation, wastewater treatment, hydrometallurgy, chromatography, biomolecular separations, and catalysis was recognized in numerous publications. The principle of covalently bonding ligands to cross-linked polymer networks became the basis for the area of polymer-supported reagents. The journal Industrial & Engineering Chemistry Research and its predecessors have published some of the most important papers in this field. In celebration of its 100th anniversary, this review provides a retrospective of ion-exchange resins through publications appearing in this journal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801242v [article] Ion-exchange resins : a retrospective from industrial and engineering chemistry research [texte imprimé] / Spiro D. Alexandratos, Éditeur scientifique . - 2009 . - P. 388-398. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 388-398 Mots-clés : Chemistry Research Wastewater treatment Hydrometallurgy Chromatography Résumé : Ion-exchange resins comprise one of the most important scientific developments of the 20th century. Their applicability to water softening, environmental remediation, wastewater treatment, hydrometallurgy, chromatography, biomolecular separations, and catalysis was recognized in numerous publications. The principle of covalently bonding ligands to cross-linked polymer networks became the basis for the area of polymer-supported reagents. The journal Industrial & Engineering Chemistry Research and its predecessors have published some of the most important papers in this field. In celebration of its 100th anniversary, this review provides a retrospective of ion-exchange resins through publications appearing in this journal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801242v

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Neutralization of acidic wastewater by the use of waste limestone from the marble industry. Mechanistic aspects and mass transfer phenomena of the acid-base reaction at the liquid-solid interface / Domenico Petruzzelli in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 399-405 Titre : Neutralization of acidic wastewater by the use of waste limestone from the marble industry. Mechanistic aspects and mass transfer phenomena of the acid-base reaction at the liquid-solid interface Type de document : texte imprimé Auteurs : Domenico Petruzzelli, Éditeur scientifique ; Mario Petrelle, Éditeur scientifique ; Giancarlo Boghetich, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 399-405 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Acidic wastewater Limestone Waste limestone Résumé : Waste limestone from marble cutting operations was adopted as a neutralizing agent of acidic wastewater from the glass industry. Hydrogen fluoride containing wastewater from the glass matting operations was investigated with the final aim of studying the influence of mass-transfer phenomena at the liquid−solid interface of the heterogeneous neutralization reaction as the rate determining step of the overall process. In this context, chemicals interdiffusion at the stationary liquid film (Nernst film) around the particles and/or in the particles themselves may play a relevant role as kinetic rate determining step. Specifically, the influence of the stirring speed, temperature of the liquid−solid mixture, and grain size of the limestone particles during batch neutralization operations were analyzed in order to carry-out a mechanistic study of the acid−base reaction at the liquid−solid interface. Apparently, limestone is not the best material to be used in the neutralization of HF containing wastewater because of molecular interdiffusion hindrances of the involved species. The present work is essentially aimed to the interpretation of mechanistic aspects of the neutralization reaction in the reference heterogeneous solid−liquid system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014268 [article] Neutralization of acidic wastewater by the use of waste limestone from the marble industry. Mechanistic aspects and mass transfer phenomena of the acid-base reaction at the liquid-solid interface [texte imprimé] / Domenico Petruzzelli, Éditeur scientifique ; Mario Petrelle, Éditeur scientifique ; Giancarlo Boghetich, Éditeur scientifique . - 2009 . - P. 399-405. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 399-405 Mots-clés : Acidic wastewater Limestone Waste limestone Résumé : Waste limestone from marble cutting operations was adopted as a neutralizing agent of acidic wastewater from the glass industry. Hydrogen fluoride containing wastewater from the glass matting operations was investigated with the final aim of studying the influence of mass-transfer phenomena at the liquid−solid interface of the heterogeneous neutralization reaction as the rate determining step of the overall process. In this context, chemicals interdiffusion at the stationary liquid film (Nernst film) around the particles and/or in the particles themselves may play a relevant role as kinetic rate determining step. Specifically, the influence of the stirring speed, temperature of the liquid−solid mixture, and grain size of the limestone particles during batch neutralization operations were analyzed in order to carry-out a mechanistic study of the acid−base reaction at the liquid−solid interface. Apparently, limestone is not the best material to be used in the neutralization of HF containing wastewater because of molecular interdiffusion hindrances of the involved species. The present work is essentially aimed to the interpretation of mechanistic aspects of the neutralization reaction in the reference heterogeneous solid−liquid system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014268

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Relationship between the surface properties and the catalytic performance of Al-, Ga-, and AlGa-pillared saponites / Miguel Angel Vicente in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 406-414 Titre : Relationship between the surface properties and the catalytic performance of Al-, Ga-, and AlGa-pillared saponites Type de document : texte imprimé Auteurs : Miguel Angel Vicente, Éditeur scientifique ; Carolina Belver, Éditeur scientifique ; Mikhail Sychev, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 406-414 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Surface properties Catalytic performance Physicochemical characteristics Résumé : A saponite from Ballarat, CA was intercalated with solutions containing only-Al, only-Ga, and two mixed AlGa-polycations, with various Al/Ga ratios. The pillared solids were obtained by calcination of the intercalated precursors at two temperatures, 300 and 500 °C. The physicochemical characteristics of the solids were studied by several techniques (XRD, N2 adsorption at −196 °C, TG, DTA, FT-IR and UV−vis−NIR) and also by means of their behavior in various acid-catalyzed reactions. All the solids showed layered, ordered structure with basal spacings of ca. 18 Å and high specific surface areas between 247 and 387 m2/g (intercalated solids), 236 and 320 m2/g (calcined at 300 °C), and 201 and 331 m2/g (calcined at 500 °C). The materials were tested as catalysts in several reactions, including liquid-phase (rearrangement of α-pinene to camphene and methanol addition to 3,4-dihydropyran) and gas-phase processes (dehydration of the alcohols 2-methyl-3-butyn-2-ol and 2-propanol and cumene conversion). The catalytic behavior of the solids was discussed in terms of their surface properties and synthesis procedure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801301a [article] Relationship between the surface properties and the catalytic performance of Al-, Ga-, and AlGa-pillared saponites [texte imprimé] / Miguel Angel Vicente, Éditeur scientifique ; Carolina Belver, Éditeur scientifique ; Mikhail Sychev, Éditeur scientifique . - 2009 . - P. 406-414. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 406-414 Mots-clés : Surface properties Catalytic performance Physicochemical characteristics Résumé : A saponite from Ballarat, CA was intercalated with solutions containing only-Al, only-Ga, and two mixed AlGa-polycations, with various Al/Ga ratios. The pillared solids were obtained by calcination of the intercalated precursors at two temperatures, 300 and 500 °C. The physicochemical characteristics of the solids were studied by several techniques (XRD, N2 adsorption at −196 °C, TG, DTA, FT-IR and UV−vis−NIR) and also by means of their behavior in various acid-catalyzed reactions. All the solids showed layered, ordered structure with basal spacings of ca. 18 Å and high specific surface areas between 247 and 387 m2/g (intercalated solids), 236 and 320 m2/g (calcined at 300 °C), and 201 and 331 m2/g (calcined at 500 °C). The materials were tested as catalysts in several reactions, including liquid-phase (rearrangement of α-pinene to camphene and methanol addition to 3,4-dihydropyran) and gas-phase processes (dehydration of the alcohols 2-methyl-3-butyn-2-ol and 2-propanol and cumene conversion). The catalytic behavior of the solids was discussed in terms of their surface properties and synthesis procedure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801301a

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Method for determination of the main bottleneck enzyme in a metabolic reaction network by dynamic sensitivity analysis / Fumihide Shiraishi in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 415-423 Titre : Method for determination of the main bottleneck enzyme in a metabolic reaction network by dynamic sensitivity analysis Type de document : texte imprimé Auteurs : Fumihide Shiraishi, Éditeur scientifique ; Yusuke Suzuki, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 415-423 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Enzyme Dynamic logarithmic gains Résumé : In fermentation processes, it is important to identify the bottleneck enzyme in a given metabolic reaction network, because increasing its activity would lead to an enhancement in the productivity of a desired metabolite. To efficiently identify the bottleneck enzyme, the present work discusses a systematic approach using dynamic logarithmic gains, i.e., percentage changes in the concentration of the desired metabolite in the response to an infinitesimal percentage change in enzyme activities, as an indicator. A penicillin V fed-batch fermentation model proposed by other researchers was used as an example of application. The calculated results showed that not only the time courses of the dynamic logarithmic gains but also the ranking of the magnitudes of their values is changed with time, implying that the bottleneck enzyme is changed with time in this fermentation process. To determine the bottleneck enzyme from such time-transient behaviors, the dynamic logarithmic gains were integrated over the entire fermentation period and divided by the total process time. The time-averaged dynamic logarithmic gains thus calculated were then ranked according to the magnitudes of their values. However, this ranking, corresponding to the ranking of candidate bottleneck enzymes, was not identical to that obtained with regard to the total amount of the desired metabolite produced as a result of finite change in each enzyme activity. This is because the concentration of the substrate for the reaction catalyzed by the relevant enzyme displays a decreasing behavior, so that the degree of increase in the corresponding flux was smaller for the finite increase of the enzyme activity and the total amount of the desired metabolite did not proportionally increase. When the concentration of the substrate for the reaction catalyzed by the most likely bottleneck enzyme displays a decreasing behavior, therefore, it is necessary to check not only the ranking of the time-average dynamic logarithmic gains but also whether the total amount of the desired metabolite is ranked first when the relevant enzyme activity is finitely changed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005963 [article] Method for determination of the main bottleneck enzyme in a metabolic reaction network by dynamic sensitivity analysis [texte imprimé] / Fumihide Shiraishi, Éditeur scientifique ; Yusuke Suzuki, Éditeur scientifique . - 2009 . - P. 415-423. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 415-423 Mots-clés : Enzyme Dynamic logarithmic gains Résumé : In fermentation processes, it is important to identify the bottleneck enzyme in a given metabolic reaction network, because increasing its activity would lead to an enhancement in the productivity of a desired metabolite. To efficiently identify the bottleneck enzyme, the present work discusses a systematic approach using dynamic logarithmic gains, i.e., percentage changes in the concentration of the desired metabolite in the response to an infinitesimal percentage change in enzyme activities, as an indicator. A penicillin V fed-batch fermentation model proposed by other researchers was used as an example of application. The calculated results showed that not only the time courses of the dynamic logarithmic gains but also the ranking of the magnitudes of their values is changed with time, implying that the bottleneck enzyme is changed with time in this fermentation process. To determine the bottleneck enzyme from such time-transient behaviors, the dynamic logarithmic gains were integrated over the entire fermentation period and divided by the total process time. The time-averaged dynamic logarithmic gains thus calculated were then ranked according to the magnitudes of their values. However, this ranking, corresponding to the ranking of candidate bottleneck enzymes, was not identical to that obtained with regard to the total amount of the desired metabolite produced as a result of finite change in each enzyme activity. This is because the concentration of the substrate for the reaction catalyzed by the relevant enzyme displays a decreasing behavior, so that the degree of increase in the corresponding flux was smaller for the finite increase of the enzyme activity and the total amount of the desired metabolite did not proportionally increase. When the concentration of the substrate for the reaction catalyzed by the most likely bottleneck enzyme displays a decreasing behavior, therefore, it is necessary to check not only the ranking of the time-average dynamic logarithmic gains but also whether the total amount of the desired metabolite is ranked first when the relevant enzyme activity is finitely changed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005963

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Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model / Qinghua Zhang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 424-429 Titre : Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model Type de document : texte imprimé Auteurs : Qinghua Zhang, Éditeur scientifique ; Zai-Sha Mao, Éditeur scientifique ; Chao Yang, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 424-429 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Barium sulfate Mixing of reagents Precipitation processes Résumé : Mixing of reagents is very important in precipitation processes, as it can significantly affect the size distribution and morphology of products. In this work, the influence of turbulent mixing on the course of barium sulfate precipitation process in a continuous stirred tank was investigated with multiple-time-scale turbulent mixer model. The effect of various operating conditions such as feed concentration, stirrer speed, and mean residence time on the barium sulfate precipitation process was clearly demonstrated. The simulation results were compared to the literature data, and good agreement is observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800722f [article] Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model [texte imprimé] / Qinghua Zhang, Éditeur scientifique ; Zai-Sha Mao, Éditeur scientifique ; Chao Yang, Éditeur scientifique . - 2009 . - P. 424-429. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 424-429 Mots-clés : Barium sulfate Mixing of reagents Precipitation processes Résumé : Mixing of reagents is very important in precipitation processes, as it can significantly affect the size distribution and morphology of products. In this work, the influence of turbulent mixing on the course of barium sulfate precipitation process in a continuous stirred tank was investigated with multiple-time-scale turbulent mixer model. The effect of various operating conditions such as feed concentration, stirrer speed, and mean residence time on the barium sulfate precipitation process was clearly demonstrated. The simulation results were compared to the literature data, and good agreement is observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800722f

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Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction / Diogo Mendes in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 430-439 Titre : Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction Type de document : texte imprimé Auteurs : Diogo Mendes, Éditeur scientifique ; Hermenegildo Garcia, Éditeur scientifique ; V. B. Silva, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 430-439 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-gas Gold and copper Electron microscopy CO2 H2 Résumé : In this paper the catalytic performances for the low-temperature water−gas shift reaction of Au/TiO2 type A (from World Gold Council), Au/CeO2 (developed at UPV-CSIC), CuO/Al2O3 (from BASF), and CuO/ZnO/Al2O3 (from REB Research & Consulting) have been compared. The catalysts were characterized by different techniques such as Raman spectroscopy, BET surface area measurements, temperature-programmed reduction, and high-resolution transmission electron microscopy, which gave additional information on the redox properties and textural and morphological structure of the investigated samples. The performances of these catalysts were evaluated in a wide range of operating conditions in a micro packed-bed reactor. It was observed that the presence of reaction products in the feed (CO2 and H2), as well as CO and H2O feed concentrations, have significant effects on the catalytic performances. With a typical reformate feed the Au/CeO2 catalyst reveals the highest CO conversion at the lowest temperature investigated (150 °C). However, while in the long tests performed the CuO/ZnO/Al2O3 catalyst showed a good stability for the entire range of temperatures tested (150−300 °C), the Au/CeO2 sample clearly showed two distinct behaviors: a progressive deactivation at lower temperatures and a good stability at higher ones. The selection of the best catalytic system is therefore clearly dependent upon the range of temperatures used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010676 [article] Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction [texte imprimé] / Diogo Mendes, Éditeur scientifique ; Hermenegildo Garcia, Éditeur scientifique ; V. B. Silva, Éditeur scientifique . - 2009 . - P. 430-439. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 430-439 Mots-clés : Water-gas Gold and copper Electron microscopy CO2 H2 Résumé : In this paper the catalytic performances for the low-temperature water−gas shift reaction of Au/TiO2 type A (from World Gold Council), Au/CeO2 (developed at UPV-CSIC), CuO/Al2O3 (from BASF), and CuO/ZnO/Al2O3 (from REB Research & Consulting) have been compared. The catalysts were characterized by different techniques such as Raman spectroscopy, BET surface area measurements, temperature-programmed reduction, and high-resolution transmission electron microscopy, which gave additional information on the redox properties and textural and morphological structure of the investigated samples. The performances of these catalysts were evaluated in a wide range of operating conditions in a micro packed-bed reactor. It was observed that the presence of reaction products in the feed (CO2 and H2), as well as CO and H2O feed concentrations, have significant effects on the catalytic performances. With a typical reformate feed the Au/CeO2 catalyst reveals the highest CO conversion at the lowest temperature investigated (150 °C). However, while in the long tests performed the CuO/ZnO/Al2O3 catalyst showed a good stability for the entire range of temperatures tested (150−300 °C), the Au/CeO2 sample clearly showed two distinct behaviors: a progressive deactivation at lower temperatures and a good stability at higher ones. The selection of the best catalytic system is therefore clearly dependent upon the range of temperatures used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010676

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A mild simple method for liquid-phase selective catalytic oxidation of toluene with ozone over CeO2 promoted sulfated TiO2 / Bo Wang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 440-445 Titre : A mild simple method for liquid-phase selective catalytic oxidation of toluene with ozone over CeO2 promoted sulfated TiO2 Type de document : texte imprimé Auteurs : Bo Wang, Éditeur scientifique ; Wei Mao, Éditeur scientifique ; Hongzhu Ma, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 440-445 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oxidation of toluene Ozone ozone−  air Résumé : A new clean catalytic process for liquid phase selective oxidation of toluene has been carried out on CeO2 promoted sulfated TiO2 (SO42−/TiO2−CeO2, abbreviated as STC) catalyst with ozone−air at ambient temperature and atmospheric pressure. Neither solvent nor promoters are needed in the reaction system. STC were found to exhibit good catalytic reactivity for the selective oxidation of toluene. For comparison, a series of single and complex oxides were also investigated including pure TiO2, SO42−/TiO2 (abbreviated as ST). The total conversion and yield to the selective products exhibited by STC were superior to those catalysts exhibited in the presence of ozone. The highest conversion of toluene was found to be 9.7% with 77% selectivity to benzaldehyde and benzyl alcohol on the STC. The anatase phase was found to be dominating in the STC by means of X-ray diffraction. By utilization of the N2 adsorption method, it was detected that the Brunauer−Emmett−Teller surface area of STC was higher than other samples. Other techniques such as scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy were also employed to characterize the property of catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800725h [article] A mild simple method for liquid-phase selective catalytic oxidation of toluene with ozone over CeO2 promoted sulfated TiO2 [texte imprimé] / Bo Wang, Éditeur scientifique ; Wei Mao, Éditeur scientifique ; Hongzhu Ma, Éditeur scientifique . - 2009 . - P. 440-445. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 440-445 Mots-clés : Oxidation of toluene Ozone ozone−  air Résumé : A new clean catalytic process for liquid phase selective oxidation of toluene has been carried out on CeO2 promoted sulfated TiO2 (SO42−/TiO2−CeO2, abbreviated as STC) catalyst with ozone−air at ambient temperature and atmospheric pressure. Neither solvent nor promoters are needed in the reaction system. STC were found to exhibit good catalytic reactivity for the selective oxidation of toluene. For comparison, a series of single and complex oxides were also investigated including pure TiO2, SO42−/TiO2 (abbreviated as ST). The total conversion and yield to the selective products exhibited by STC were superior to those catalysts exhibited in the presence of ozone. The highest conversion of toluene was found to be 9.7% with 77% selectivity to benzaldehyde and benzyl alcohol on the STC. The anatase phase was found to be dominating in the STC by means of X-ray diffraction. By utilization of the N2 adsorption method, it was detected that the Brunauer−Emmett−Teller surface area of STC was higher than other samples. Other techniques such as scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy were also employed to characterize the property of catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800725h

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Direct preparation kinetics of 1,3-dichloro-2-propanol from glycerol using acetic acid catalyst / Zheng-Hong Luo in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 446-452 Titre : Direct preparation kinetics of 1,3-dichloro-2-propanol from glycerol using acetic acid catalyst Type de document : texte imprimé Auteurs : Zheng-Hong Luo, Éditeur scientifique ; Xiao-Zi You, Éditeur scientifique ; Hua-Rong Li, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 446-452 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dichloropropène Glycerol Acetic Acid Catalyst Kinetic model Résumé : Direct preparation of 1,3-dichloro-2-propanol from glycerol is carried out in a batch reactor using acetic acid catalyst at 363−393 K. The analytical technique, gas chromatography, is employed in order to follow the time evolution of the reagents. The kinetic model of the process is developed. Furthermore, the model parameters of the process are also determined by data fitting. The results show that direct preparation follows the SN2 mechanism. A kinetic model corresponding to the mechanism is proposed in this work. The experimental results show that the kinetic model agrees well with the experiments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011177 [article] Direct preparation kinetics of 1,3-dichloro-2-propanol from glycerol using acetic acid catalyst [texte imprimé] / Zheng-Hong Luo, Éditeur scientifique ; Xiao-Zi You, Éditeur scientifique ; Hua-Rong Li, Éditeur scientifique . - 2009 . - P. 446-452. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 446-452 Mots-clés : Dichloropropène Glycerol Acetic Acid Catalyst Kinetic model Résumé : Direct preparation of 1,3-dichloro-2-propanol from glycerol is carried out in a batch reactor using acetic acid catalyst at 363−393 K. The analytical technique, gas chromatography, is employed in order to follow the time evolution of the reagents. The kinetic model of the process is developed. Furthermore, the model parameters of the process are also determined by data fitting. The results show that direct preparation follows the SN2 mechanism. A kinetic model corresponding to the mechanism is proposed in this work. The experimental results show that the kinetic model agrees well with the experiments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011177

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Thermal stability and dispersion behavior of nanostructured CexZr1-xO2 mixed oxides over anatase-TiO2 / Benjaram M. Reddy in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 453-462 Titre : Thermal stability and dispersion behavior of nanostructured CexZr1-xO2 mixed oxides over anatase-TiO2 : a combined study of CO oxidation and characterization by XRD, XPS, TPR, HREM, and UV-Vis DRS Type de document : texte imprimé Auteurs : Benjaram M. Reddy, Éditeur scientifique ; Pankaj Bharali, Éditeur scientifique ; Pranjal Saikia, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 453-462 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nanostructured CexZr1−  xO2 Thermal stability Oxides Anatase-TiO2 Résumé : A study has been undertaken on the thermal stability and dispersion behavior of nanostructured CexZr1−xO2 mixed oxides over anatase-TiO2 support, synthesized by a deposition coprecipitation method and subjected to heat treatments at different temperatures. An unsupported CexZr1−xO2 mixed oxide was also synthesized by coprecipitation method for the purpose of comparison. The structural/morphological characterization was performed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HREM), X-ray photoelectron spectroscopy (XPS), UV−visible diffuse reflectance spectroscopy (UV−vis DRS), and temperature-programmed reduction (TPR) techniques. XRD measurements revealed the presence of cubic Ce0.75Zr0.25O2 phase at 773 K and incorporation of more zirconium into the ceria lattice at higher temperatures. HREM analysis conformed highly dispersed Ce−Zr nano-oxides over anatase-TiO2 support having the sizes in the range of 3−5 nm at 773 K. At higher temperatures, a slight increase in the crystallite size (5−10 nm) has been observed. The XPS measurements revealed the stabilization of Ce3+ at higher temperatures and presence of Zr and Ti in 4+ oxidation states. UV−vis DRS studies showed that oxygen to metal (Ce4+/Ce3+) charge-transfer transitions occur at lower wavelengths in the case of CexZr1−xO2/TiO2 compared to pure CexZr1−xO2. TPR experiments revealed that the surface reduction of CexZr1−xO2/TiO2 takes place at lower temperatures, which facilitates better CO oxidation activity in comparison to the unsupported CexZr1−xO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012677 [article] Thermal stability and dispersion behavior of nanostructured CexZr1-xO2 mixed oxides over anatase-TiO2 : a combined study of CO oxidation and characterization by XRD, XPS, TPR, HREM, and UV-Vis DRS [texte imprimé] / Benjaram M. Reddy, Éditeur scientifique ; Pankaj Bharali, Éditeur scientifique ; Pranjal Saikia, Éditeur scientifique . - 2009 . - P. 453-462. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 453-462 Mots-clés : Nanostructured CexZr1−  xO2 Thermal stability Oxides Anatase-TiO2 Résumé : A study has been undertaken on the thermal stability and dispersion behavior of nanostructured CexZr1−xO2 mixed oxides over anatase-TiO2 support, synthesized by a deposition coprecipitation method and subjected to heat treatments at different temperatures. An unsupported CexZr1−xO2 mixed oxide was also synthesized by coprecipitation method for the purpose of comparison. The structural/morphological characterization was performed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HREM), X-ray photoelectron spectroscopy (XPS), UV−visible diffuse reflectance spectroscopy (UV−vis DRS), and temperature-programmed reduction (TPR) techniques. XRD measurements revealed the presence of cubic Ce0.75Zr0.25O2 phase at 773 K and incorporation of more zirconium into the ceria lattice at higher temperatures. HREM analysis conformed highly dispersed Ce−Zr nano-oxides over anatase-TiO2 support having the sizes in the range of 3−5 nm at 773 K. At higher temperatures, a slight increase in the crystallite size (5−10 nm) has been observed. The XPS measurements revealed the stabilization of Ce3+ at higher temperatures and presence of Zr and Ti in 4+ oxidation states. UV−vis DRS studies showed that oxygen to metal (Ce4+/Ce3+) charge-transfer transitions occur at lower wavelengths in the case of CexZr1−xO2/TiO2 compared to pure CexZr1−xO2. TPR experiments revealed that the surface reduction of CexZr1−xO2/TiO2 takes place at lower temperatures, which facilitates better CO oxidation activity in comparison to the unsupported CexZr1−xO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012677

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Integrated model for refinery planning, oil procuring, and product distribution / Pierre Guyonnet in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 463-482 Titre : Integrated model for refinery planning, oil procuring, and product distribution Type de document : texte imprimé Auteurs : Pierre Guyonnet, Éditeur scientifique ; F. Hank Grant, Éditeur scientifique ; Miguel J. Bagajewicz, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 463-482 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Refinery production planning Oil Procuring Product Distribution Résumé : Refinery production planning is usually performed using the refinery battery limit constraints. Two associated problems are the oil uploading and product distribution problems. These problems have traditionally been solved separately, and they have constraints that could render the solution of the planning problem infeasible or less profitable. The goal of this paper is to explore the benefits of the integration of production planning with these two models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701712z [article] Integrated model for refinery planning, oil procuring, and product distribution [texte imprimé] / Pierre Guyonnet, Éditeur scientifique ; F. Hank Grant, Éditeur scientifique ; Miguel J. Bagajewicz, Éditeur scientifique . - 2009 . - P. 463-482. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 463-482 Mots-clés : Refinery production planning Oil Procuring Product Distribution Résumé : Refinery production planning is usually performed using the refinery battery limit constraints. Two associated problems are the oil uploading and product distribution problems. These problems have traditionally been solved separately, and they have constraints that could render the solution of the planning problem infeasible or less profitable. The goal of this paper is to explore the benefits of the integration of production planning with these two models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701712z

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A continuous-time tightened formulation for single-stage batch scheduling with sequence-dependent changeovers / Pablo A. Marchetti in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 483-498 Titre : A continuous-time tightened formulation for single-stage batch scheduling with sequence-dependent changeovers Type de document : texte imprimé Auteurs : Pablo A. Marchetti, Éditeur scientifique ; Jaime Cerdá, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 483-498 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mixed-integer linear programming (MILP) Multiproduct batch plants Résumé : This work presents a new mixed-integer linear programming (MILP) continuous-time approach for the short-term scheduling of single-stage multiproduct batch plants with parallel units and sequence-dependent changeovers. It uses a unit-specific precedence-based representation, combined with effective, nontrivial tightening constraints, to develop a very efficient problem formulation. The additional cuts account for the updated information provided by allocation and sequencing binary variables to systematically reduce the solution space of the corresponding LP at every node of the enumeration tree. In this way, close bounds for key variables like makespan, task earliness, and task starting/completion times are generated and continually improved throughout the search in order to accelerate the node pruning process. Alternative problem objectives like the minimum total earliness or the shortest makespan can be managed. To make a thorough comparison with previous continuous-time scheduling approaches, several benchmark examples have been solved. Results show that the proposed approach usually presents the best computational performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701774w [article] A continuous-time tightened formulation for single-stage batch scheduling with sequence-dependent changeovers [texte imprimé] / Pablo A. Marchetti, Éditeur scientifique ; Jaime Cerdá, Éditeur scientifique . - 2009 . - P. 483-498. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 483-498 Mots-clés : Mixed-integer linear programming (MILP) Multiproduct batch plants Résumé : This work presents a new mixed-integer linear programming (MILP) continuous-time approach for the short-term scheduling of single-stage multiproduct batch plants with parallel units and sequence-dependent changeovers. It uses a unit-specific precedence-based representation, combined with effective, nontrivial tightening constraints, to develop a very efficient problem formulation. The additional cuts account for the updated information provided by allocation and sequencing binary variables to systematically reduce the solution space of the corresponding LP at every node of the enumeration tree. In this way, close bounds for key variables like makespan, task earliness, and task starting/completion times are generated and continually improved throughout the search in order to accelerate the node pruning process. Alternative problem objectives like the minimum total earliness or the shortest makespan can be managed. To make a thorough comparison with previous continuous-time scheduling approaches, several benchmark examples have been solved. Results show that the proposed approach usually presents the best computational performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701774w

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Mnemonic enhancement optimization (MEO) for real-time optimization of industrial processes / Xueyi Fang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 499-509 Titre : Mnemonic enhancement optimization (MEO) for real-time optimization of industrial processes Type de document : texte imprimé Auteurs : Xueyi Fang, Éditeur scientifique ; Zhijiang Shao, Éditeur scientifique ; Zhiqiang Wang, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 499-509 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mnemonic Enhancement Optimization (MEO) of Industrial Real-time optimization (RTO) Résumé : In this paper, the model-based real-time optimization (RTO) is viewed as a kind of nonlinear parametric optimization problem which is solved repeatedly when parameter values change. A novel RTO strategy—mnemonic enhancement optimization (MEO)—is proposed. The method preserves the past optimal solutions and corresponding parameter values as experience and approximates the optimum based on the experience. The approximation is used by the optimization algorithm as a starting point to find the real optimum. The optimum is proved to be a continuous function of the parameter. This ensures that the distance between the optimum and the initial point tends to decrease as RTO continues to run. Thus MEO can improve the performance of RTO continually. Numerical experiments illustrate the continuity of the optimal set mapping, and the MEO method is compared with the traditional method. The results show that MEO outperforms the traditional method concerning the solution time, the number of iterations, and the percentage of successful optimizations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800166p [article] Mnemonic enhancement optimization (MEO) for real-time optimization of industrial processes [texte imprimé] / Xueyi Fang, Éditeur scientifique ; Zhijiang Shao, Éditeur scientifique ; Zhiqiang Wang, Éditeur scientifique . - 2009 . - P. 499-509. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 499-509 Mots-clés : Mnemonic Enhancement Optimization (MEO) of Industrial Real-time optimization (RTO) Résumé : In this paper, the model-based real-time optimization (RTO) is viewed as a kind of nonlinear parametric optimization problem which is solved repeatedly when parameter values change. A novel RTO strategy—mnemonic enhancement optimization (MEO)—is proposed. The method preserves the past optimal solutions and corresponding parameter values as experience and approximates the optimum based on the experience. The approximation is used by the optimization algorithm as a starting point to find the real optimum. The optimum is proved to be a continuous function of the parameter. This ensures that the distance between the optimum and the initial point tends to decrease as RTO continues to run. Thus MEO can improve the performance of RTO continually. Numerical experiments illustrate the continuity of the optimal set mapping, and the MEO method is compared with the traditional method. The results show that MEO outperforms the traditional method concerning the solution time, the number of iterations, and the percentage of successful optimizations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800166p

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Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes / Zhigang Wang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 510-516 Titre : Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes Type de document : texte imprimé Auteurs : Zhigang Wang, Éditeur scientifique ; Naitao Yang, Éditeur scientifique ; Bo Meng, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 510-516 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oxygen Hollow fiber membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite powders having a submicrometer size were synthesized by a sol−gel autocombustion method. From these powders, the gastight LSCF hollow-fiber membranes with a highly asymmetric structure comprising a dense layer of thickness ca. 88 μm integrated with a porous substrate were fabricated in a single step through a phase inversion/sintering technique with a mixture of N-methyl-2-pyrrolidone (NMP) and water as internal coagulant. Oxygen permeation fluxes through the obtained hollow-fiber membranes were measured under air/He gradients at different temperatures. The results indicate that the highly asymmetric hollow-fiber membranes possess an oxygen permeation flux of 0.11−2.19 mL cm−2 min−1 in the temperature range of 650−1000 °C, which is 2.6−10.5 times higher than that of the sandwich-structured hollow-fiber membranes. Oxygen permeation in the hollow-fiber membranes is limited primarily by the surface exchange reactions at lower temperatures, but ionic bulk diffusion will have a rate-limiting effect at temperatures higher than 900 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010462 [article] Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes [texte imprimé] / Zhigang Wang, Éditeur scientifique ; Naitao Yang, Éditeur scientifique ; Bo Meng, Éditeur scientifique . - 2009 . - P. 510-516. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 510-516 Mots-clés : Oxygen Hollow fiber membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite powders having a submicrometer size were synthesized by a sol−gel autocombustion method. From these powders, the gastight LSCF hollow-fiber membranes with a highly asymmetric structure comprising a dense layer of thickness ca. 88 μm integrated with a porous substrate were fabricated in a single step through a phase inversion/sintering technique with a mixture of N-methyl-2-pyrrolidone (NMP) and water as internal coagulant. Oxygen permeation fluxes through the obtained hollow-fiber membranes were measured under air/He gradients at different temperatures. The results indicate that the highly asymmetric hollow-fiber membranes possess an oxygen permeation flux of 0.11−2.19 mL cm−2 min−1 in the temperature range of 650−1000 °C, which is 2.6−10.5 times higher than that of the sandwich-structured hollow-fiber membranes. Oxygen permeation in the hollow-fiber membranes is limited primarily by the surface exchange reactions at lower temperatures, but ionic bulk diffusion will have a rate-limiting effect at temperatures higher than 900 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010462

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Effect of perforated ratios of distributor on the fluidization characteristics in a gas-solid fluidized bed / Shuqin Dong in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 517-527 Titre : Effect of perforated ratios of distributor on the fluidization characteristics in a gas-solid fluidized bed Type de document : texte imprimé Auteurs : Shuqin Dong, Éditeur scientifique ; Changqing Cao, Éditeur scientifique ; Chongdian Si, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 517-527 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas−  Solid Fluid dynamics Résumé : A gas−solid fluidized bed, 0.14 m in diameter and 1.6 m in height, was employed to investigate systematically the effects of perforated ratios of distributor on fluidization characteristics with air as gas phase and fluid catalytic cracking particles as solid phase. The distributions of the distributor pressure drop, solid particle concentration, and bed pressure drop were obtained by means of different perforated ratios of distributors. The particle concentration distribution and bed pressure drop were measured by a PV-6A particles velocity measurer and a U-manometer, respectively. The parameters of bed pressure drop, distributor pressure drop, the instantaneous evolution of bubbles, and profile of radial solid holdups adopted three perforated ratios of distributors were simulated using computational fluid dynamics code Fluent 6.2. The results showed that the distributor pressure drop decreased with increasing perforated ratios and decreasing superficial gas velocity. The global solid holdup decreased from the wall to center region, and it had parabolic concentration profile under pressure-driven force for different perforated ratios of three distributors investigated. However, the distribution of radial solid holdup was more homogeneous, and it had a better agreement with experiment values for perforated ratio 0.46% of distributor than that for perforated ratio 0.86 or 1.10% of distributors. The bubble size at the region of distributor decreased with increasing perforated ratio of distributors, and it had more obvious circulation motion of solid particles for the perforated ratio 0.46% of distributor than that for perforated ratio 0.86 or 1.10% of distributor. The bed pressure drop and root mean square (rms) of bed pressure drop in gas−solid fluidized bed appeared differently for three perforated ratios of distributors. The rms of bed pressure drop for the perforated ratio 0.46% of distributor was larger than that for perforated ratio 0.86 or 1.10% of distributors, and the larger discrepancy occurred as the perforated ratio of distributor was 0.46%. The numerical simulation results agreed well with the experimental data at low superficial gas velocity for calculation of distributor pressure drop. However, larger error occurred at high superficial gas velocity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801073r [article] Effect of perforated ratios of distributor on the fluidization characteristics in a gas-solid fluidized bed [texte imprimé] / Shuqin Dong, Éditeur scientifique ; Changqing Cao, Éditeur scientifique ; Chongdian Si, Éditeur scientifique . - 2009 . - P. 517-527. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 517-527 Mots-clés : Gas−  Solid Fluid dynamics Résumé : A gas−solid fluidized bed, 0.14 m in diameter and 1.6 m in height, was employed to investigate systematically the effects of perforated ratios of distributor on fluidization characteristics with air as gas phase and fluid catalytic cracking particles as solid phase. The distributions of the distributor pressure drop, solid particle concentration, and bed pressure drop were obtained by means of different perforated ratios of distributors. The particle concentration distribution and bed pressure drop were measured by a PV-6A particles velocity measurer and a U-manometer, respectively. The parameters of bed pressure drop, distributor pressure drop, the instantaneous evolution of bubbles, and profile of radial solid holdups adopted three perforated ratios of distributors were simulated using computational fluid dynamics code Fluent 6.2. The results showed that the distributor pressure drop decreased with increasing perforated ratios and decreasing superficial gas velocity. The global solid holdup decreased from the wall to center region, and it had parabolic concentration profile under pressure-driven force for different perforated ratios of three distributors investigated. However, the distribution of radial solid holdup was more homogeneous, and it had a better agreement with experiment values for perforated ratio 0.46% of distributor than that for perforated ratio 0.86 or 1.10% of distributors. The bubble size at the region of distributor decreased with increasing perforated ratio of distributors, and it had more obvious circulation motion of solid particles for the perforated ratio 0.46% of distributor than that for perforated ratio 0.86 or 1.10% of distributor. The bed pressure drop and root mean square (rms) of bed pressure drop in gas−solid fluidized bed appeared differently for three perforated ratios of distributors. The rms of bed pressure drop for the perforated ratio 0.46% of distributor was larger than that for perforated ratio 0.86 or 1.10% of distributors, and the larger discrepancy occurred as the perforated ratio of distributor was 0.46%. The numerical simulation results agreed well with the experimental data at low superficial gas velocity for calculation of distributor pressure drop. However, larger error occurred at high superficial gas velocity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801073r

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Production of AlN by carbothermal and methanothermal reduction of Al2O3 in a N2 flow using concentrated thermal radiation / M. E Gálvez in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 528-533 Titre : Production of AlN by carbothermal and methanothermal reduction of Al2O3 in a N2 flow using concentrated thermal radiation Type de document : texte imprimé Auteurs : M. E Gálvez, Éditeur scientifique ; A. Frei, Éditeur scientifique ; F. Meier, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 528-533 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Production of AlN Carbothermal and Methanothermal Reduction Thermal Radiation Carbon metals (Fe, Ni) Résumé : The production of AlN by thermal reduction of Al2O3 in a N2 flow, with C/CH4 as reducing agents, is investigated using concentrated thermal radiation as the energy source of high-temperature process heat. Samples were directly exposed to radiative fluxes equivalent to peak solar concentration ratios exceeding 4500 suns (1 sun = 1 kW/m2) and subjected to temperatures in the 2100−2300 K range. Experimental data were fitted to an Arrhenius-type solid−solid kinetic model with an apparent activation energy of 360 kJ·mol−1. The catalytic effect of activated carbon and metals (Fe, Ni) was examined, revealing that metallic particles served as nucleation sites for carbon filamental growth. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011193 [article] Production of AlN by carbothermal and methanothermal reduction of Al2O3 in a N2 flow using concentrated thermal radiation [texte imprimé] / M. E Gálvez, Éditeur scientifique ; A. Frei, Éditeur scientifique ; F. Meier, Éditeur scientifique . - 2009 . - P. 528-533. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 528-533 Mots-clés : Production of AlN Carbothermal and Methanothermal Reduction Thermal Radiation Carbon metals (Fe, Ni) Résumé : The production of AlN by thermal reduction of Al2O3 in a N2 flow, with C/CH4 as reducing agents, is investigated using concentrated thermal radiation as the energy source of high-temperature process heat. Samples were directly exposed to radiative fluxes equivalent to peak solar concentration ratios exceeding 4500 suns (1 sun = 1 kW/m2) and subjected to temperatures in the 2100−2300 K range. Experimental data were fitted to an Arrhenius-type solid−solid kinetic model with an apparent activation energy of 360 kJ·mol−1. The catalytic effect of activated carbon and metals (Fe, Ni) was examined, revealing that metallic particles served as nucleation sites for carbon filamental growth. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011193

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Physical mechanism of ultrasound-assisted synthesis of biodiesel / Abhishek Kalva in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 534-544 Titre : Physical mechanism of ultrasound-assisted synthesis of biodiesel Type de document : texte imprimé Auteurs : Abhishek Kalva, Éditeur scientifique ; Thirugnanasambandam Sivasankar, Éditeur scientifique ; Vijayanand S. Moholkar, Éditeur scientifique Année de publication : 2009 Article en page(s) : P. 534-544 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrasound-Assisted Physical Mechanism Synthesis of Biodiesel Résumé : Acceleration of the transesterification reaction for synthesis of biodiesel by application of ultrasound is known. This paper tries to establish the mechanism of this enhancement by discriminating between physical and chemical effects of ultrasound. Experiments with different conditions have been coupled to a bubble dynamics model. It is revealed that influence of ultrasound on transesterification reaction is of purely physical nature. Formation of fine emulsion between oil and alcohol due to microturbulence generated by cavitation bubbles generates enormous interfacial area, which accelerates the reaction. For the power input used in the present experiments, the temperature peak reached in transient collapse of cavitation bubble in methanol is found to be too low to produce any radical species, which can induce transesterification reaction. The yield of the reaction is found to have an optimum with respect to alcohol to oil molar ratio. This result is attributed to the difference in intensity of microturbulence produced by cavitation bubbles in oil and methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800269g [article] Physical mechanism of ultrasound-assisted synthesis of biodiesel [texte imprimé] / Abhishek Kalva, Éditeur scientifique ; Thirugnanasambandam Sivasankar, Éditeur scientifique ; Vijayanand S. Moholkar, Éditeur scientifique . - 2009 . - P. 534-544. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 534-544 Mots-clés : Ultrasound-Assisted Physical Mechanism Synthesis of Biodiesel Résumé : Acceleration of the transesterification reaction for synthesis of biodiesel by application of ultrasound is known. This paper tries to establish the mechanism of this enhancement by discriminating between physical and chemical effects of ultrasound. Experiments with different conditions have been coupled to a bubble dynamics model. It is revealed that influence of ultrasound on transesterification reaction is of purely physical nature. Formation of fine emulsion between oil and alcohol due to microturbulence generated by cavitation bubbles generates enormous interfacial area, which accelerates the reaction. For the power input used in the present experiments, the temperature peak reached in transient collapse of cavitation bubble in methanol is found to be too low to produce any radical species, which can induce transesterification reaction. The yield of the reaction is found to have an optimum with respect to alcohol to oil molar ratio. This result is attributed to the difference in intensity of microturbulence produced by cavitation bubbles in oil and methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800269g

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