Documents disponibles écrits par cet auteur

Effect of distributor design on the bottom zone hydrodynamics in a fluidized bed dryer using 1-D X-ray densitometry imaging / Michael Wormsbecker in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7004–7015 Titre : Effect of distributor design on the bottom zone hydrodynamics in a fluidized bed dryer using 1-D X-ray densitometry imaging Type de document : texte imprimé Auteurs : Michael Wormsbecker, Auteur ; Todd Pugsley, Auteur ; J. Ruud van Ommen, Auteur Année de publication : 2009 Article en page(s) : pp. 7004–7015 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fluidized-bed  dryer  Porous  plate  distributors  One-dimensional  X-ray  densitometry  imaging Résumé : The hydrodynamics near the base of a 15 cm i.d. fluidized-bed dryer having perforated, punched, and porous plate distributors have been studied using one-dimensional X-ray densitometry imaging. The time-averaged solids concentration profiles of dry pharmaceutical granule and wet granule undergoing drying were compared. The porous plate creates good gas distribution over the bed cross section with dry granule but results in defluidization at the distributor level when the granule is wet. The perforated and punched plates exhibit different solids concentration profiles with dry granule; however, the presence of moisture results in similar hydrodynamics between the plates during drying. Standard deviation analysis of the high-frequency solids concentration data was used to corroborate the results of the time-averaged solids concentration measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900025n [article] Effect of distributor design on the bottom zone hydrodynamics in a fluidized bed dryer using 1-D X-ray densitometry imaging [texte imprimé] / Michael Wormsbecker, Auteur ; Todd Pugsley, Auteur ; J. Ruud van Ommen, Auteur . - 2009 . - pp. 7004–7015. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7004–7015 Mots-clés : Fluidized-bed  dryer  Porous  plate  distributors  One-dimensional  X-ray  densitometry  imaging Résumé : The hydrodynamics near the base of a 15 cm i.d. fluidized-bed dryer having perforated, punched, and porous plate distributors have been studied using one-dimensional X-ray densitometry imaging. The time-averaged solids concentration profiles of dry pharmaceutical granule and wet granule undergoing drying were compared. The porous plate creates good gas distribution over the bed cross section with dry granule but results in defluidization at the distributor level when the granule is wet. The perforated and punched plates exhibit different solids concentration profiles with dry granule; however, the presence of moisture results in similar hydrodynamics between the plates during drying. Standard deviation analysis of the high-frequency solids concentration data was used to corroborate the results of the time-averaged solids concentration measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900025n

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

Public ISBD [article]  in Industrial & 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, Editeur scientifique ; J. Ruud van Ommen, Editeur scientifique ; John Nijenhuis, Editeur 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, Editeur scientifique ; J. Ruud van Ommen, Editeur scientifique ; John Nijenhuis, Editeur 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

Influence of Distributed Secondary Gas Injection on the Performance of a Bubbling Fluidized-Bed Reactor / D. Christensen in Industrial & engineering chemistry research, Vol. 47 N°10 (Mai 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3601–3618 Titre : Influence of Distributed Secondary Gas Injection on the Performance of a Bubbling Fluidized-Bed Reactor Type de document : texte imprimé Auteurs : D. Christensen, Auteur ; J. Nijenhuis, Auteur ; J. Ruud van Ommen, Auteur ; M.-O. Coppen, Auteur Année de publication : 2008 Article en page(s) : p. 3601–3618 Langues : Anglais (eng) Mots-clés : Bubbling  Fluidized-bed  reactor  ;  Gas  injection Résumé : Distributed secondary gas injection via a fractal injector was studied in a lab-scale 3-D fluidized bed to determine its effect on bubble size, bubble fraction, residence time, mixing, and conversion. The experimental results indicate improved reactor performance and are consistent with earlier work in 2-D beds. A model was developed based on simple two-phase theory that describes the effect of distributed secondary injection on the performance of ozone decomposition in a bubbling fluidized bed. The model was used to predict the performance of a reactor for the production of maleic anhydride from n-butane, which includes consecutive and side reactions. The results showed that the production and selectivity of maleic anhydride were significantly improved. It can be concluded that distributed secondary gas injection improves the mass transfer and gas−solid contact, which results in increased reactor performance. It likely achieves these improvements by enhanced gas flow through the dense phase and more micromixing around the injection points, which causes greater interaction between the phases. Some aspects of applying this technology in industry are discussed. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie071376p [article] Influence of Distributed Secondary Gas Injection on the Performance of a Bubbling Fluidized-Bed Reactor [texte imprimé] / D. Christensen, Auteur ; J. Nijenhuis, Auteur ; J. Ruud van Ommen, Auteur ; M.-O. Coppen, Auteur . - 2008 . - p. 3601–3618. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3601–3618 Mots-clés : Bubbling  Fluidized-bed  reactor  ;  Gas  injection Résumé : Distributed secondary gas injection via a fractal injector was studied in a lab-scale 3-D fluidized bed to determine its effect on bubble size, bubble fraction, residence time, mixing, and conversion. The experimental results indicate improved reactor performance and are consistent with earlier work in 2-D beds. A model was developed based on simple two-phase theory that describes the effect of distributed secondary injection on the performance of ozone decomposition in a bubbling fluidized bed. The model was used to predict the performance of a reactor for the production of maleic anhydride from n-butane, which includes consecutive and side reactions. The results showed that the production and selectivity of maleic anhydride were significantly improved. It can be concluded that distributed secondary gas injection improves the mass transfer and gas−solid contact, which results in increased reactor performance. It likely achieves these improvements by enhanced gas flow through the dense phase and more micromixing around the injection points, which causes greater interaction between the phases. Some aspects of applying this technology in industry are discussed. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie071376p

Structured Packings for Multiphase Catalytic Reactors / Kalyani Pangarkar in Industrial & engineering chemistry research, Vol. 47 N°10 (Mai 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3720-3751 Titre : Structured Packings for Multiphase Catalytic Reactors Type de document : texte imprimé Auteurs : Kalyani Pangarkar, Auteur ; Tilman J. Schildhauer, Auteur ; J. Ruud van Ommen, Auteur Année de publication : 2008 Article en page(s) : p. 3720-3751 Langues : Anglais (eng) Mots-clés : Structured  packings Résumé : Reactor design for multiphase catalytic fixed bed reactors is always based on conflicting objectives. In the past, catalyst discovery and development preceded and motivated the selection of an appropriate multiphase reactor type. This type of sequential approach is increasingly been replaced by a parallel approach to catalyst and reactor selection. In nearly all respects, structured catalysts and reactors have the ability to outperform randomly packed reactors. Structured packings, apart from their advantages of high voidage and low-pressure drop, have the benefit of ease of scale-up and accurate description of the fluid mechanics. In this review we have evaluated the potential of using structured internals for multiphase catalytic reactions, which are currently carried out in randomly packed fixed bed reactors. Characteristics of various structured internals such as monoliths, corrugated sheet or gauze packings, knitted wire packings and foams are discussed in detail. Since designing a structured device for gas−liquid−solid contacting requires a sound knowledge of hydrodynamics and transport phenomena, a concise review of the above-mentioned structured packings and their characteristics based on hydrodynamics and transport phenomena is presented. Existing models (empirical, phenomenological and mechanistic) are outlined with respect to flow regime transition, pressure drop, liquid hold-up, gas−liquid interfacial area, gas to liquid mass transfer, liquid to solid mass transfer, residence time distribution (RTD), and heat transfer. The models are critically evaluated, and their limitations are discussed. An overview is given about what information is available, what needs to be evaluated and what kind of existing methodology can be applied in order to arrive at quantitative models for the physical parameters. Last, the structured internals are compared with each other and with randomly packed bed reactors, allowing a rational selection of the preferred packing for a given application. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie800067r [article] Structured Packings for Multiphase Catalytic Reactors [texte imprimé] / Kalyani Pangarkar, Auteur ; Tilman J. Schildhauer, Auteur ; J. Ruud van Ommen, Auteur . - 2008 . - p. 3720-3751. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3720-3751 Mots-clés : Structured  packings Résumé : Reactor design for multiphase catalytic fixed bed reactors is always based on conflicting objectives. In the past, catalyst discovery and development preceded and motivated the selection of an appropriate multiphase reactor type. This type of sequential approach is increasingly been replaced by a parallel approach to catalyst and reactor selection. In nearly all respects, structured catalysts and reactors have the ability to outperform randomly packed reactors. Structured packings, apart from their advantages of high voidage and low-pressure drop, have the benefit of ease of scale-up and accurate description of the fluid mechanics. In this review we have evaluated the potential of using structured internals for multiphase catalytic reactions, which are currently carried out in randomly packed fixed bed reactors. Characteristics of various structured internals such as monoliths, corrugated sheet or gauze packings, knitted wire packings and foams are discussed in detail. Since designing a structured device for gas−liquid−solid contacting requires a sound knowledge of hydrodynamics and transport phenomena, a concise review of the above-mentioned structured packings and their characteristics based on hydrodynamics and transport phenomena is presented. Existing models (empirical, phenomenological and mechanistic) are outlined with respect to flow regime transition, pressure drop, liquid hold-up, gas−liquid interfacial area, gas to liquid mass transfer, liquid to solid mass transfer, residence time distribution (RTD), and heat transfer. The models are critically evaluated, and their limitations are discussed. An overview is given about what information is available, what needs to be evaluated and what kind of existing methodology can be applied in order to arrive at quantitative models for the physical parameters. Last, the structured internals are compared with each other and with randomly packed bed reactors, allowing a rational selection of the preferred packing for a given application. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie800067r