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Absorption Mass-Transfer Characteristics of Mellapak Packings Series / L. Valenz in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 12134-12142 Titre : Absorption Mass-Transfer Characteristics of Mellapak Packings Series Type de document : texte imprimé Auteurs : L. Valenz, Auteur ; F. J. Rejl, Auteur ; J. Síma, Auteur Année de publication : 2011 Article en page(s) : pp. 12134-12142 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Mass  transfer Résumé : Mass-transfer characteristics were measured for the Mellapak structured packing series 250Y, 350Y, 452Y, and 500Y. kLa was measured by oxygen desorption from water and the effective mass-transfer area a by absorption of CO2 into NaOH solution and also by oxygen absorption into a sulfite solution. Using Bodenstein numbers determined by means of the "cold" air-water dynamic experiments, effects of gas- and liquid-phase axial mixing on the characteristics were evaluated for Mellapak 250Y. Strikingly large differences found between the mass-transfer parameters and their flow dependencies measured in this work and those predicted by models especially designed for the prediction of the parameters in corrugated sheet structured packings (Billet, R.; Schultes, M. Chem. Eng. Res. Des. 1999, 77, 498; Rocha, J. A.; Bravo, J. L.; Fair, J. R. Ind. Eng. Chem. Res. 1996, 35, 1660; Olujić, Z.; Kamerbeek, A. B.; Graauw, J. Chem. Eng. Process. 1999,38,683) demonstrate the bad physical relevance of the parameters predicted. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697530 [article] Absorption Mass-Transfer Characteristics of Mellapak Packings Series [texte imprimé] / L. Valenz, Auteur ; F. J. Rejl, Auteur ; J. Síma, Auteur . - 2011 . - pp. 12134-12142. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 12134-12142 Mots-clés : Mass  transfer Résumé : Mass-transfer characteristics were measured for the Mellapak structured packing series 250Y, 350Y, 452Y, and 500Y. kLa was measured by oxygen desorption from water and the effective mass-transfer area a by absorption of CO2 into NaOH solution and also by oxygen absorption into a sulfite solution. Using Bodenstein numbers determined by means of the "cold" air-water dynamic experiments, effects of gas- and liquid-phase axial mixing on the characteristics were evaluated for Mellapak 250Y. Strikingly large differences found between the mass-transfer parameters and their flow dependencies measured in this work and those predicted by models especially designed for the prediction of the parameters in corrugated sheet structured packings (Billet, R.; Schultes, M. Chem. Eng. Res. Des. 1999, 77, 498; Rocha, J. A.; Bravo, J. L.; Fair, J. R. Ind. Eng. Chem. Res. 1996, 35, 1660; Olujić, Z.; Kamerbeek, A. B.; Graauw, J. Chem. Eng. Process. 1999,38,683) demonstrate the bad physical relevance of the parameters predicted. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697530

Gas and liquid axial mixing in the column packed with mellapak 250Y, pall rings 25, and intalox saddles 25 under flow conditions prevailing in distillation columns / L. Valenz in Industrial & engineering chemistry research, Vol. 49 N° 20 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 10016-10025 Titre : Gas and liquid axial mixing in the column packed with mellapak 250Y, pall rings 25, and intalox saddles 25 under flow conditions prevailing in distillation columns Type de document : texte imprimé Auteurs : L. Valenz, Auteur ; F. J. Rejl, Auteur ; V. Linek, Auteur Année de publication : 2011 Article en page(s) : pp. 10016-10025 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Distillation  column  Pall  ring  Axial  mixing Résumé : The axial dispersions of gas and liquid phase in a column of inner diameter 0.297 m packed with random packing of metal Pall rings 25 and Intalox saddles 25 and structured packing of Mellapak 250Y were measured using a dynamic method under hydraulic conditions common in distillation columns, i.e., liquid flow rate from 6.94 x 10-4 to 0.0111 m/s and gas flow rate from 0.25 to 2 m/s. The two-response method with a diffusion-type model was used to reproduce the experimental response curves. Axial mixing in the gas increases with gas and liquid rates for both random and structured packings, but the dependence on the gas rate is very weak for the structured packing. The largest gas mixing was found for the Pall rings at the highest gas rate; the least was found for the structured packing at the lowest gas and liquid rates. Liquid-phase axial mixing increases with decreasing liquid flow rate and is independent of gas flow rate for both random and structured packings. The largest liquid mixing was found for the Intalox saddles at the lowest liquid rate; the least was found for the structured packing. The correlations of BoL and BoG numbers deduced for all types of packings used reproduced the experimental data within ±22%. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23325824 [article] Gas and liquid axial mixing in the column packed with mellapak 250Y, pall rings 25, and intalox saddles 25 under flow conditions prevailing in distillation columns [texte imprimé] / L. Valenz, Auteur ; F. J. Rejl, Auteur ; V. Linek, Auteur . - 2011 . - pp. 10016-10025. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 10016-10025 Mots-clés : Distillation  column  Pall  ring  Axial  mixing Résumé : The axial dispersions of gas and liquid phase in a column of inner diameter 0.297 m packed with random packing of metal Pall rings 25 and Intalox saddles 25 and structured packing of Mellapak 250Y were measured using a dynamic method under hydraulic conditions common in distillation columns, i.e., liquid flow rate from 6.94 x 10-4 to 0.0111 m/s and gas flow rate from 0.25 to 2 m/s. The two-response method with a diffusion-type model was used to reproduce the experimental response curves. Axial mixing in the gas increases with gas and liquid rates for both random and structured packings, but the dependence on the gas rate is very weak for the structured packing. The largest gas mixing was found for the Pall rings at the highest gas rate; the least was found for the structured packing at the lowest gas and liquid rates. Liquid-phase axial mixing increases with decreasing liquid flow rate and is independent of gas flow rate for both random and structured packings. The largest liquid mixing was found for the Intalox saddles at the lowest liquid rate; the least was found for the structured packing. The correlations of BoL and BoG numbers deduced for all types of packings used reproduced the experimental data within ±22%. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23325824

“Profile method” for the measurement of kLa and kVa in distillation columns. validation of rate - based distillation models using concentration profiles measured along the column / F. J. Rejl in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp 4383–4398 Titre : “Profile method” for the measurement of kLa and kVa in distillation columns. validation of rate - based distillation models using concentration profiles measured along the column Type de document : texte imprimé Auteurs : F. J. Rejl, Auteur ; L. Valenz, Auteur ; V. Linek, Auteur Année de publication : 2010 Article en page(s) : pp 4383–4398 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Distillation  Columns Résumé : The “profile method” enables the determination of vapor- and liquid-side volumetric mass-transfer coefficients kVa and kLa by comparing the concentration profiles measured in both phases in a distillation column with the simulated profiles. The method is based on the fact that the shape of the concentration profiles along the column depend significantly on the distribution of the mass-transfer resistance between the liquid and vapor phases. This makes it possible to measure kLa and kVa directly in the distillation columns, in the same manner that is possible in absorption columns, and therefore to validate the distillation models more conclusively than by means of comparing the experimental and calculated height equivalent to a theoretical plate values. The coefficients were measured on structured packing Mellapak250Y. A small axial mixing of phases on this type of packing enables the use of a plug-flow model for both phases. Three distillation systems, methanol−ethanol, ethanol−propanol, and methanol−propanol, were used under total reflux and atmospheric pressure. Samples of the phases were withdrawn directly from the column packing by means of special sampling devices. The dependence of the individual transport coefficients on the phase flow rate was obtained by changing the reboiler duty. The dependencies were compared with those predicted by the following three mass-transfer correlations developed for packed columns: RBF (Rocha et al. Ind. Eng. Chem. Res. 1996, 35, 1660), BS (Billet, R.; Schultes, M. Trans. Inst. Chem. Eng. 1999, 77, 498), and DELFT (Olujic et al. Chem. Eng. Proc. 1999, 38, 683). The coefficients obtained by the profile method differ substantially from those calculated from the original models. Specifically, all of the original models considerably overvalue the kLa coefficients (RBF by up to 2 times, BS by up to 1.5 times, and DELFT by up to 6.3 times) and undervalue the kVa coefficients (all by up to 2 times). The dependence of the mass-transfer coefficients on the rate of the phases predicted by any of the original models is not consistent with that of the profile method. It has also been shown that the experimental concentration profiles strongly differ from the profiles calculated from the Aspen Plus simulation program. The correlations of the kLa and kVa coefficients with improved flow dependencies according to the profile method are presented. The concentration profiles calculated from the improved correlations fit the profiles accurately. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901690m [article] “Profile method” for the measurement of kLa and kVa in distillation columns. validation of rate - based distillation models using concentration profiles measured along the column [texte imprimé] / F. J. Rejl, Auteur ; L. Valenz, Auteur ; V. Linek, Auteur . - 2010 . - pp 4383–4398. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp 4383–4398 Mots-clés : Distillation  Columns Résumé : The “profile method” enables the determination of vapor- and liquid-side volumetric mass-transfer coefficients kVa and kLa by comparing the concentration profiles measured in both phases in a distillation column with the simulated profiles. The method is based on the fact that the shape of the concentration profiles along the column depend significantly on the distribution of the mass-transfer resistance between the liquid and vapor phases. This makes it possible to measure kLa and kVa directly in the distillation columns, in the same manner that is possible in absorption columns, and therefore to validate the distillation models more conclusively than by means of comparing the experimental and calculated height equivalent to a theoretical plate values. The coefficients were measured on structured packing Mellapak250Y. A small axial mixing of phases on this type of packing enables the use of a plug-flow model for both phases. Three distillation systems, methanol−ethanol, ethanol−propanol, and methanol−propanol, were used under total reflux and atmospheric pressure. Samples of the phases were withdrawn directly from the column packing by means of special sampling devices. The dependence of the individual transport coefficients on the phase flow rate was obtained by changing the reboiler duty. The dependencies were compared with those predicted by the following three mass-transfer correlations developed for packed columns: RBF (Rocha et al. Ind. Eng. Chem. Res. 1996, 35, 1660), BS (Billet, R.; Schultes, M. Trans. Inst. Chem. Eng. 1999, 77, 498), and DELFT (Olujic et al. Chem. Eng. Proc. 1999, 38, 683). The coefficients obtained by the profile method differ substantially from those calculated from the original models. Specifically, all of the original models considerably overvalue the kLa coefficients (RBF by up to 2 times, BS by up to 1.5 times, and DELFT by up to 6.3 times) and undervalue the kVa coefficients (all by up to 2 times). The dependence of the mass-transfer coefficients on the rate of the phases predicted by any of the original models is not consistent with that of the profile method. It has also been shown that the experimental concentration profiles strongly differ from the profiles calculated from the Aspen Plus simulation program. The correlations of the kLa and kVa coefficients with improved flow dependencies according to the profile method are presented. The concentration profiles calculated from the improved correlations fit the profiles accurately. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901690m