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Efficient polymerization inhibition systems for acrylic acid distillation / Jaroslav Mosnacek 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. 3910–3915 Titre : Efficient polymerization inhibition systems for acrylic acid distillation : New liquid - phase inhibitors Type de document : texte imprimé Auteurs : Jaroslav Mosnacek, Auteur ; Renaud Nicolay, Auteur ; Kishore K. Kar, Auteur Année de publication : 2012 Article en page(s) : pp. 3910–3915 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Polymerization  Acid  distillation Résumé : Phenothiazine and other compounds with similar structures, namely, phenoxazine, promazine, promazine hydrochloride, N,N′-dimethylphenazine, carbazole, N-ethylcarbazole, N-benzylphenothiazine, and N-(1-phenylethyl)phenothiazine were tested as liquid-phase inhibitors for acrylic acid. N-Alkylated phenothiazine (PTZ) derivatives, such as N-benzylphenothiazine and especially N-(1-phenylethyl)phenothiazine, showed improved efficiency for liquid-phase inhibition, in comparison with PTZ. It was also shown that N-alkylated PTZ derivatives could be used in combination with nitroso compounds that can be employed as vapor-phase inhibitors. The combination of N-(1-phenylethyl)phenothiazine and nitrosobenzene showed superior liquid-phase-inhibition efficiency, with time to gelation of >122 h, in comparison with 64 h obtained with PTZ alone. The structure of liquid-phase inhibitors had no influence on the extent of Michael addition reactions during heating of acrylic acid. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201708n [article] Efficient polymerization inhibition systems for acrylic acid distillation : New liquid - phase inhibitors [texte imprimé] / Jaroslav Mosnacek, Auteur ; Renaud Nicolay, Auteur ; Kishore K. Kar, Auteur . - 2012 . - pp. 3910–3915. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 3910–3915 Mots-clés : Polymerization  Acid  distillation Résumé : Phenothiazine and other compounds with similar structures, namely, phenoxazine, promazine, promazine hydrochloride, N,N′-dimethylphenazine, carbazole, N-ethylcarbazole, N-benzylphenothiazine, and N-(1-phenylethyl)phenothiazine were tested as liquid-phase inhibitors for acrylic acid. N-Alkylated phenothiazine (PTZ) derivatives, such as N-benzylphenothiazine and especially N-(1-phenylethyl)phenothiazine, showed improved efficiency for liquid-phase inhibition, in comparison with PTZ. It was also shown that N-alkylated PTZ derivatives could be used in combination with nitroso compounds that can be employed as vapor-phase inhibitors. The combination of N-(1-phenylethyl)phenothiazine and nitrosobenzene showed superior liquid-phase-inhibition efficiency, with time to gelation of >122 h, in comparison with 64 h obtained with PTZ alone. The structure of liquid-phase inhibitors had no influence on the extent of Michael addition reactions during heating of acrylic acid. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201708n

Efficient polymerization inhibition systems for acrylic acid distillation / Renaud Nicolay in Industrial & engineering chemistry research, Vol. 51 N° 12 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4467–4471 Titre : Efficient polymerization inhibition systems for acrylic acid distillation : Vapor - phase inhibitors Type de document : texte imprimé Auteurs : Renaud Nicolay, Auteur ; Jaroslav Mosnacek, Auteur ; Kishore K. Kar, Auteur Année de publication : 2012 Article en page(s) : pp. 4467–4471 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Acrylic  acid  Polymerization  Vapor  phase Résumé : Nitroso compounds, such as 2-methyl-2-nitrosopropane, nitrosobenzene, and 4-nitrosophenol, were tested as volatile inhibitors for vapor-phase inhibition of acrylic acid polymerization during its reflux at 113 °C under reduced pressure. The experimental parameters were set to mimic the conditions employed for the industrial distillation of acrylic acid. Nitrosobenzene was found to be the most efficient vapor-phase inhibitor for the distillation of acrylic acid. The inhibition time was also found to be dependent on the pressure used for the experiments. Decreasing the pressure from 110 to 85 mbar resulted in an almost 2-fold increase in the inhibition time. The combination of nitrosobenzene with a liquid-phase inhibitor, namely, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, significantly improved the efficiency of vapor-phase inhibition by decreasing the consumption of nitrosobenzene in the liquid phase. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201709y [article] Efficient polymerization inhibition systems for acrylic acid distillation : Vapor - phase inhibitors [texte imprimé] / Renaud Nicolay, Auteur ; Jaroslav Mosnacek, Auteur ; Kishore K. Kar, Auteur . - 2012 . - pp. 4467–4471. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4467–4471 Mots-clés : Acrylic  acid  Polymerization  Vapor  phase Résumé : Nitroso compounds, such as 2-methyl-2-nitrosopropane, nitrosobenzene, and 4-nitrosophenol, were tested as volatile inhibitors for vapor-phase inhibition of acrylic acid polymerization during its reflux at 113 °C under reduced pressure. The experimental parameters were set to mimic the conditions employed for the industrial distillation of acrylic acid. Nitrosobenzene was found to be the most efficient vapor-phase inhibitor for the distillation of acrylic acid. The inhibition time was also found to be dependent on the pressure used for the experiments. Decreasing the pressure from 110 to 85 mbar resulted in an almost 2-fold increase in the inhibition time. The combination of nitrosobenzene with a liquid-phase inhibitor, namely, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, significantly improved the efficiency of vapor-phase inhibition by decreasing the consumption of nitrosobenzene in the liquid phase. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201709y

KT-3: a novel tickler for solids removal from slurry vessels / Richard F. Cope in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4990–4997 Titre : KT-3: a novel tickler for solids removal from slurry vessels Type de document : texte imprimé Auteurs : Richard F. Cope, Auteur ; Kishore K. Kar, Auteur Année de publication : 2009 Article en page(s) : pp. 4990–4997 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ticklers  Slurry  vessels Résumé : Ticklers are relatively small impellers operating near the bottom of slurry-containing stirred-tank reactors and storage vessels. They maintain solids suspension after the level of a draining slurry recedes below the main impeller(s). Typical pitched-blade or flat-blade ticklers suspend solids, but often simultaneously starve the pump and protract drainage times by throwing material out toward the wall instead of in toward the centerline discharge nozzle. After the slurry liquid eventually drains, solids deposited on the vessel bottom and wall are often removable only by extraneous liquid sprays. By contrast, the recently designed KT-3 tickler minimizes solids heels while simultaneously avoiding pump starvation and prolonged drainage times. It does so by swirling the slurry so that it washes the unbaffled vessel bottom and sweeps solids toward the centerline exit. KT-3 ticklers have been successfully installed in vessels used in many processing industries including those for basic and fine chemicals, minerals, pharmaceuticals, and food products. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801221t [article] KT-3: a novel tickler for solids removal from slurry vessels [texte imprimé] / Richard F. Cope, Auteur ; Kishore K. Kar, Auteur . - 2009 . - pp. 4990–4997. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4990–4997 Mots-clés : Ticklers  Slurry  vessels Résumé : Ticklers are relatively small impellers operating near the bottom of slurry-containing stirred-tank reactors and storage vessels. They maintain solids suspension after the level of a draining slurry recedes below the main impeller(s). Typical pitched-blade or flat-blade ticklers suspend solids, but often simultaneously starve the pump and protract drainage times by throwing material out toward the wall instead of in toward the centerline discharge nozzle. After the slurry liquid eventually drains, solids deposited on the vessel bottom and wall are often removable only by extraneous liquid sprays. By contrast, the recently designed KT-3 tickler minimizes solids heels while simultaneously avoiding pump starvation and prolonged drainage times. It does so by swirling the slurry so that it washes the unbaffled vessel bottom and sweeps solids toward the centerline exit. KT-3 ticklers have been successfully installed in vessels used in many processing industries including those for basic and fine chemicals, minerals, pharmaceuticals, and food products. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801221t

Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems / Zhao Yu in Industrial & engineering chemistry research, Vol. 51 N° 46 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15282–15292 Titre : Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems Type de document : texte imprimé Auteurs : Zhao Yu, Auteur ; Richard F. Cope, Auteur ; Kishore K. Kar, Auteur Année de publication : 2013 Article en page(s) : pp. 15282–15292 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Laboratory  scale  Agitator  Mixer  Mixing Résumé : Small (<100 mL) lab-scale systems for rapid screening are widely employed in research and development in chemistry and biology, but commonly encounter significant mixing challenges. Researchers from the Engineering and Process Sciences Laboratory of The Dow Chemical Company developed and patented a novel Kar Dynamic Mixer (KDM) impeller for overhead mixing within such unbaffled systems. This impeller consists of multiple twisted ribbon elements mounted on a rotating shaft. Through laboratory experiments and computational fluid dynamics (CFD) simulations, the performance of the KDM impeller was compared to that of vendor-offered impellers in three different lab-scale mixing systems. In fluid viscosities ranging from 5000 to 30 000 cP, the KDM impeller produced the desired mixing in significantly less time than each commercially offered impeller system. Experiments and simulations characterized KDM impeller operations and yielded the recommended ratios of KDM diameter-to-vial diameter (D/T), liquid submergence-to-KDM diameter (s/D), and off-bottom clearance-to-KDM diameter (c/D). The optimal speed at which the KDM impeller rotates depends on the fluid system of interest. The design of the KDM impeller was refined for the applications described in this work by optimizing the length-to-diameter ratio (L/D) of the impeller elements, as well as the number of repeated KDM elements so as to meet the recommended values of s/D, c/D, and L/D. Other crucial features of the optimized KDM design included twisting all elements in the same direction (be it clockwise or counter-clockwise), and the 90 degree offset angle between adjacent elements. The KDM impeller is well suited to laboratory scales, but its high relative mass could make it impractical at some larger scales, depending on fluids of interest and materials of construction. Identifying the size at which the KDM becomes impractical was beyond the current effort. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679649 [article] Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems [texte imprimé] / Zhao Yu, Auteur ; Richard F. Cope, Auteur ; Kishore K. Kar, Auteur . - 2013 . - pp. 15282–15292. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15282–15292 Mots-clés : Laboratory  scale  Agitator  Mixer  Mixing Résumé : Small (<100 mL) lab-scale systems for rapid screening are widely employed in research and development in chemistry and biology, but commonly encounter significant mixing challenges. Researchers from the Engineering and Process Sciences Laboratory of The Dow Chemical Company developed and patented a novel Kar Dynamic Mixer (KDM) impeller for overhead mixing within such unbaffled systems. This impeller consists of multiple twisted ribbon elements mounted on a rotating shaft. Through laboratory experiments and computational fluid dynamics (CFD) simulations, the performance of the KDM impeller was compared to that of vendor-offered impellers in three different lab-scale mixing systems. In fluid viscosities ranging from 5000 to 30 000 cP, the KDM impeller produced the desired mixing in significantly less time than each commercially offered impeller system. Experiments and simulations characterized KDM impeller operations and yielded the recommended ratios of KDM diameter-to-vial diameter (D/T), liquid submergence-to-KDM diameter (s/D), and off-bottom clearance-to-KDM diameter (c/D). The optimal speed at which the KDM impeller rotates depends on the fluid system of interest. The design of the KDM impeller was refined for the applications described in this work by optimizing the length-to-diameter ratio (L/D) of the impeller elements, as well as the number of repeated KDM elements so as to meet the recommended values of s/D, c/D, and L/D. Other crucial features of the optimized KDM design included twisting all elements in the same direction (be it clockwise or counter-clockwise), and the 90 degree offset angle between adjacent elements. The KDM impeller is well suited to laboratory scales, but its high relative mass could make it impractical at some larger scales, depending on fluids of interest and materials of construction. Identifying the size at which the KDM becomes impractical was beyond the current effort. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679649