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Simulation of settling of solid particles due to sudden impeller stoppage / Madhavi V. Sardeshpande in Industrial & engineering chemistry research, Vol. 51 N° 10 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 4112–4118 Titre : Simulation of settling of solid particles due to sudden impeller stoppage Type de document : texte imprimé Auteurs : Madhavi V. Sardeshpande, Auteur ; Vivek V. Ranade, Auteur Année de publication : 2012 Article en page(s) : pp. 4112–4118 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Process  industries  Catalytic  reactions Résumé : Stirred tank reactors (STRs), which are used in process industries (for a variety of operations, such as catalytic reactions, dissolution of a solid, crystallization, and so on), often involve handling of solid–liquid (−gas) systems. The solid suspension and the quality of the suspension are key issues in the design and operation of such stirred reactors. Despite extensive experimental work over previous decades, comprehensive understanding and reliable methods to predict the solids suspension and the quality of the suspension are not yet available. Advances in computational fluid dynamics (CFD) and new experimental techniques offer potentially effective ways of understanding solids suspension in stirred tanks. The present work highlights the potential of using transient measurements by way of the dynamic settling of solid particles because of the sudden stoppage of an impeller to evaluate CFD models. Sudden impeller stoppage results in significantly different conditions, in terms of the ratio of particle diameter to Kolomogorov length scale (dp/λ), as well as the solids volume fraction experienced by solid particles. Therefore, experimental data under such sudden impeller stoppage offer a better way to evaluate the influence of prevailing turbulence and solids volume fraction on effective drag and therefore offer a more-stringent test to CFD models than steady-state profiles. Besides facilitating the development of computational models, the experimental and simulation studies of sudden impeller stoppage also provide useful data to gain insight into the behavior of the stirred tank after abrupt impeller stoppage due to sudden power failure. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2028987 [article] Simulation of settling of solid particles due to sudden impeller stoppage [texte imprimé] / Madhavi V. Sardeshpande, Auteur ; Vivek V. Ranade, Auteur . - 2012 . - pp. 4112–4118. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 4112–4118 Mots-clés : Process  industries  Catalytic  reactions Résumé : Stirred tank reactors (STRs), which are used in process industries (for a variety of operations, such as catalytic reactions, dissolution of a solid, crystallization, and so on), often involve handling of solid–liquid (−gas) systems. The solid suspension and the quality of the suspension are key issues in the design and operation of such stirred reactors. Despite extensive experimental work over previous decades, comprehensive understanding and reliable methods to predict the solids suspension and the quality of the suspension are not yet available. Advances in computational fluid dynamics (CFD) and new experimental techniques offer potentially effective ways of understanding solids suspension in stirred tanks. The present work highlights the potential of using transient measurements by way of the dynamic settling of solid particles because of the sudden stoppage of an impeller to evaluate CFD models. Sudden impeller stoppage results in significantly different conditions, in terms of the ratio of particle diameter to Kolomogorov length scale (dp/λ), as well as the solids volume fraction experienced by solid particles. Therefore, experimental data under such sudden impeller stoppage offer a better way to evaluate the influence of prevailing turbulence and solids volume fraction on effective drag and therefore offer a more-stringent test to CFD models than steady-state profiles. Besides facilitating the development of computational models, the experimental and simulation studies of sudden impeller stoppage also provide useful data to gain insight into the behavior of the stirred tank after abrupt impeller stoppage due to sudden power failure. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2028987

Solid suspension and liquid phase mixing in solid−liquid stirred tanks / Madhavi V. Sardeshpande in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9713–9722 Titre : Solid suspension and liquid phase mixing in solid−liquid stirred tanks Type de document : texte imprimé Auteurs : Madhavi V. Sardeshpande, Auteur ; Aparna R. Sagi, Auteur ; Vinay A. Juvekar, Auteur Année de publication : 2010 Article en page(s) : pp. 9713–9722 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Stirred  tanks  Catalytic  reactions  Crystallization Résumé : Stirred tanks are widely used in chemical process industries for catalytic reactions, dissolution of solids, crystallization, and so on. In designing and optimizing such processes, suspension quality of slurry is an important parameter. Suspension quality depends upon complex interactions of impeller generated flow, turbulence, and solid loading. Most of the earlier work on solid suspension focuses on identifying critical impeller speed for just suspension of solids (Njs). In this study, apart from Njs, aspects like cloud height and liquid phase mixing in solid−liquid suspensions were also studied. A new way of characterizing solid−liquid suspensions and liquid phase mixing using nonintrusive wall pressure fluctuation measurements has been developed. Systematic experimental data on Njs, cloud height, power consumption, mixing time, and circulation time over a range of solid volume fraction and impeller speeds have been presented here. The results and discussion presented here will have useful implications for designing solid−liquid stirred tanks. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801858a [article] Solid suspension and liquid phase mixing in solid−liquid stirred tanks [texte imprimé] / Madhavi V. Sardeshpande, Auteur ; Aparna R. Sagi, Auteur ; Vinay A. Juvekar, Auteur . - 2010 . - pp. 9713–9722. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9713–9722 Mots-clés : Stirred  tanks  Catalytic  reactions  Crystallization Résumé : Stirred tanks are widely used in chemical process industries for catalytic reactions, dissolution of solids, crystallization, and so on. In designing and optimizing such processes, suspension quality of slurry is an important parameter. Suspension quality depends upon complex interactions of impeller generated flow, turbulence, and solid loading. Most of the earlier work on solid suspension focuses on identifying critical impeller speed for just suspension of solids (Njs). In this study, apart from Njs, aspects like cloud height and liquid phase mixing in solid−liquid suspensions were also studied. A new way of characterizing solid−liquid suspensions and liquid phase mixing using nonintrusive wall pressure fluctuation measurements has been developed. Systematic experimental data on Njs, cloud height, power consumption, mixing time, and circulation time over a range of solid volume fraction and impeller speeds have been presented here. The results and discussion presented here will have useful implications for designing solid−liquid stirred tanks. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801858a