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Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide / Xuemei Zhang in Industrial & engineering chemistry research, Vol. 51 N° 18 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 18 (Mai 2012) . - pp. 6563-6570 Titre : Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide Type de document : texte imprimé Auteurs : Xuemei Zhang, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur Année de publication : 2012 Article en page(s) : pp. 6563-6570 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Density  functional  method Résumé : The reductive decomposition of calcium sulfate (CaSO4) to calcium sulfide (CaS) was one of the most important methods for anhydrite resource utilization. When CaSO4 was decomposed reductively by carbon monoxide (CO), usually there were CaS and/or calcium oxide (CaO) in the decomposition products of CaSO4 depending on the reaction temperature and readant concentrations. In this paper, the mechanism of CaSO4 reductive decomposition by CO was studied in the framework of density functional theory (DFT). In the calculation, the exchange-correlation term was approximated by Perdew―Wang (PW91), a functional within the generalized gradient approximation (GGA) family. To study the interaction of CO and CaSO4, the transition states of CaSO4 decomposition and the minimum energy path (MEP) were analyzed. The results showed that the CaS product could be obtained when CaSO4 was reduced by CO with the 4:1 stoichiometric ratio of CO and CaSO4, and the decomposition of CaSO4 to CaSO3 was the rate-determining step, and activation energy in this step was 191.19 kJ/mol. With the inaease of the reaction temperature, the CaO product could be obtained with a 1:1 stoichiometric ratio of CO and CaSO4, and the activation energy is 318.28 kj/mol during the process. It was found that the CaS product was formatted at a lower reaction temperature and a higher mole ratio of CO and CaSO4, and the CaO product was preferred at a higher reaction temperature and a lower mole ratio of CO and CaSO4. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25867306 [article] Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide [texte imprimé] / Xuemei Zhang, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur . - 2012 . - pp. 6563-6570. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 18 (Mai 2012) . - pp. 6563-6570 Mots-clés : Density  functional  method Résumé : The reductive decomposition of calcium sulfate (CaSO4) to calcium sulfide (CaS) was one of the most important methods for anhydrite resource utilization. When CaSO4 was decomposed reductively by carbon monoxide (CO), usually there were CaS and/or calcium oxide (CaO) in the decomposition products of CaSO4 depending on the reaction temperature and readant concentrations. In this paper, the mechanism of CaSO4 reductive decomposition by CO was studied in the framework of density functional theory (DFT). In the calculation, the exchange-correlation term was approximated by Perdew―Wang (PW91), a functional within the generalized gradient approximation (GGA) family. To study the interaction of CO and CaSO4, the transition states of CaSO4 decomposition and the minimum energy path (MEP) were analyzed. The results showed that the CaS product could be obtained when CaSO4 was reduced by CO with the 4:1 stoichiometric ratio of CO and CaSO4, and the decomposition of CaSO4 to CaSO3 was the rate-determining step, and activation energy in this step was 191.19 kJ/mol. With the inaease of the reaction temperature, the CaO product could be obtained with a 1:1 stoichiometric ratio of CO and CaSO4, and the activation energy is 318.28 kj/mol during the process. It was found that the CaS product was formatted at a lower reaction temperature and a higher mole ratio of CO and CaSO4, and the CaO product was preferred at a higher reaction temperature and a lower mole ratio of CO and CaSO4. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25867306

Effect of electromagnetic field on three - phase flow behavior / Ze Sun in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10798-10803 Titre : Effect of electromagnetic field on three - phase flow behavior Type de document : texte imprimé Auteurs : Ze Sun, Auteur ; Ping Li, Auteur ; Guimin Lu, Auteur Année de publication : 2011 Article en page(s) : pp. 10798-10803 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Three  phase  flow Résumé : The multiphase transport phenomena frequently take place in metallurgical processes, for example, in the electrolysis process of magnesium, where there exists three-phase flow including liquid magnesium, molten electrolyte, and chlorine gas under the electromagnetic field. In this paper, the three-phase flow behaviors under the electromagnetic field in the advanced diaphragmless electrolytic cell were investigated by CFD simulation. The governing equations of the internal flow field in the electrolytic cell were established, where the standard k-e turbulence model and the VOF multiphase flow model were adopted for the comprehensive description of the flow characteristics of multiphase flow in the electrolytic cell, and the Lorentz force was added to the momentum equation of fluids as the momentum source term to combine the effect of electromagnetic field with the flow field. The order coupling method was adopted for the calculation of the coupled field. The numerical simulation on the three-phase flow field considering the effect of electromagnetic field was done using FLUENT6.3 software, the numerical simulations on the electric field and the magnetic field were carried out using Ansys 11.0 software, respectively, and the connection between the finite element software ANSYS and the control volume software Fluent was built using the user-defined function (UDF). According to the analysis on the distributions of the electromagnetic field and the flow field, the optimum flow circulation in the advanced diaphragmless electrolytic cell was obtained, which is very helpful for the design in the electrolysis process of molten magnesium salt. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447972 [article] Effect of electromagnetic field on three - phase flow behavior [texte imprimé] / Ze Sun, Auteur ; Ping Li, Auteur ; Guimin Lu, Auteur . - 2011 . - pp. 10798-10803. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10798-10803 Mots-clés : Three  phase  flow Résumé : The multiphase transport phenomena frequently take place in metallurgical processes, for example, in the electrolysis process of magnesium, where there exists three-phase flow including liquid magnesium, molten electrolyte, and chlorine gas under the electromagnetic field. In this paper, the three-phase flow behaviors under the electromagnetic field in the advanced diaphragmless electrolytic cell were investigated by CFD simulation. The governing equations of the internal flow field in the electrolytic cell were established, where the standard k-e turbulence model and the VOF multiphase flow model were adopted for the comprehensive description of the flow characteristics of multiphase flow in the electrolytic cell, and the Lorentz force was added to the momentum equation of fluids as the momentum source term to combine the effect of electromagnetic field with the flow field. The order coupling method was adopted for the calculation of the coupled field. The numerical simulation on the three-phase flow field considering the effect of electromagnetic field was done using FLUENT6.3 software, the numerical simulations on the electric field and the magnetic field were carried out using Ansys 11.0 software, respectively, and the connection between the finite element software ANSYS and the control volume software Fluent was built using the user-defined function (UDF). According to the analysis on the distributions of the electromagnetic field and the flow field, the optimum flow circulation in the advanced diaphragmless electrolytic cell was obtained, which is very helpful for the design in the electrolysis process of molten magnesium salt. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447972

Novel method based on electric field simulation and optimization for designing an energy-saving magnesium electrolysis cell / Ze Sun in Industrial & engineering chemistry research, Vol. 50 N° 10 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6161-6173 Titre : Novel method based on electric field simulation and optimization for designing an energy-saving magnesium electrolysis cell Type de document : texte imprimé Auteurs : Ze Sun, Auteur ; Yun Zhao, Auteur ; Guimin Lu, Auteur Année de publication : 2011 Article en page(s) : pp. 6161-6173 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Electrolysis  cell  Energy  conservation  Optimization  Electric  field Résumé : In this study, on the basis of simulation of the electric field, the design optimization methods for 120 and 250 kA magnesium electrolysis cells were developed. A 3D numerical model was built to simulate the electric field at the steady state to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The major optimization was focused on adjustment of structural parameters, such as the relative positions of the anode and cathode, electrolyte height in the cell, and so on. An orthogonal design approach was used to optimize the structural parameters in a 120 kA cell, and the optimization criterion was applied to magnify the design of a 250 kA cell. The resistance voltage in the optimized 250 kAcell was computed, and the minimum resistance voltage was 1631.3 mV among the provided solutions. Hence, the developed model and simulation results would be useful for the design optimization of a magnesium electrolysis cell. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158915 [article] Novel method based on electric field simulation and optimization for designing an energy-saving magnesium electrolysis cell [texte imprimé] / Ze Sun, Auteur ; Yun Zhao, Auteur ; Guimin Lu, Auteur . - 2011 . - pp. 6161-6173. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6161-6173 Mots-clés : Electrolysis  cell  Energy  conservation  Optimization  Electric  field Résumé : In this study, on the basis of simulation of the electric field, the design optimization methods for 120 and 250 kA magnesium electrolysis cells were developed. A 3D numerical model was built to simulate the electric field at the steady state to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The major optimization was focused on adjustment of structural parameters, such as the relative positions of the anode and cathode, electrolyte height in the cell, and so on. An orthogonal design approach was used to optimize the structural parameters in a 120 kA cell, and the optimization criterion was applied to magnify the design of a 250 kA cell. The resistance voltage in the optimized 250 kAcell was computed, and the minimum resistance voltage was 1631.3 mV among the provided solutions. Hence, the developed model and simulation results would be useful for the design optimization of a magnesium electrolysis cell. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158915

Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures / Yanxia Xu in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 443–453 Titre : Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures Type de document : texte imprimé Auteurs : Yanxia Xu, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur Année de publication : 2012 Article en page(s) : pp. 443–453 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Multiphase  flow  Hydrocyclones Résumé : A hydrocyclone, as a common liquid/solid grading instrument, was chosen to separate calcium sulfate particles from crude carnallite during the KCl production process on the Tibetan Plateau in China, because CaSO4 particles are independent of KCl particles and have a smaller particle size distribution. The local altitude on the Tibetan Plateau in China is over 3000 m, so the effects of low atmospheric pressure on the separation performance of the hydrocyclone should be considered. In this article, the computational fluid dynamics (CFD) simulation technique was used to investigate the hydrodynamics and particles separation performance of an industrial hydrocyclone with a 428-mm diameter at both plain and plateau atmospheric pressures. In this CFD approach, the Reynolds stress model (RSM) was used to describe the turbulent fluid flow, the volume of fluid (VOF) multiphase model was used to simulate the interface between the liquid phase and the air core, and the stochastic Lagrangian model was used to track the particle flow. The mathematical models deveoped for the industrial hydrocyclone were tested by comparing the predicted results with the flow fields measured by Hsieh (Ph.D. Thesis, The University of Utah, Salt Lake City, UT, 1988). According to the simulation results, the environmental atmospheric pressures on the plain and plateau had effects mainly on the flow field inside the air core and near the interface between the air core and the liquid phase. It was found the direction of the axial velocity on the cylinder part and the values of the tangential velocity changed under the different environmental atmospheric pressures. When the industrial hydrocyclone was operated in the plateau environment, the separation efficiency for small particles decreased about 10% at the overflow, which was not good for CaSO4 removal, but there was no effect on the particles size larger than 350 μm, and more energy was consumed, although the difference in the split ratio was small. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201147e [article] Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures [texte imprimé] / Yanxia Xu, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur . - 2012 . - pp. 443–453. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 443–453 Mots-clés : Multiphase  flow  Hydrocyclones Résumé : A hydrocyclone, as a common liquid/solid grading instrument, was chosen to separate calcium sulfate particles from crude carnallite during the KCl production process on the Tibetan Plateau in China, because CaSO4 particles are independent of KCl particles and have a smaller particle size distribution. The local altitude on the Tibetan Plateau in China is over 3000 m, so the effects of low atmospheric pressure on the separation performance of the hydrocyclone should be considered. In this article, the computational fluid dynamics (CFD) simulation technique was used to investigate the hydrodynamics and particles separation performance of an industrial hydrocyclone with a 428-mm diameter at both plain and plateau atmospheric pressures. In this CFD approach, the Reynolds stress model (RSM) was used to describe the turbulent fluid flow, the volume of fluid (VOF) multiphase model was used to simulate the interface between the liquid phase and the air core, and the stochastic Lagrangian model was used to track the particle flow. The mathematical models deveoped for the industrial hydrocyclone were tested by comparing the predicted results with the flow fields measured by Hsieh (Ph.D. Thesis, The University of Utah, Salt Lake City, UT, 1988). According to the simulation results, the environmental atmospheric pressures on the plain and plateau had effects mainly on the flow field inside the air core and near the interface between the air core and the liquid phase. It was found the direction of the axial velocity on the cylinder part and the values of the tangential velocity changed under the different environmental atmospheric pressures. When the industrial hydrocyclone was operated in the plateau environment, the separation efficiency for small particles decreased about 10% at the overflow, which was not good for CaSO4 removal, but there was no effect on the particles size larger than 350 μm, and more energy was consumed, although the difference in the split ratio was small. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201147e