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Backmixing characterization of a bubble column with short venturi throats by multipoint internal tracer injections / Zi-Bin Huang in Industrial & engineering chemistry research, Vol. 51 N° 29 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9733-9741 Titre : Backmixing characterization of a bubble column with short venturi throats by multipoint internal tracer injections Type de document : texte imprimé Auteurs : Zi-Bin Huang, Auteur ; Zhen-Min Cheng, Auteur ; Jian-Ding Chen, Auteur Année de publication : 2012 Article en page(s) : pp. 9733-9741 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Tracers  Venturi  Bubble  column  Backmixing Résumé : In reduction of liquid backmixing in bubble columns, Wu et al. [Wu, Y; Cheng, Z. M.; Huang, Z. B. Backmixing reduction of a bubble column by interruption of the global liquid circulation. Ind. Eng. Chem. Res. 2009, 48, 6558― 6563] have shown that the backmixing could be substantially reduced by interrupting the global liquid circulation using four identical short Venturi throats (SVTs). Considering the advantages of such structures, it is necessary to further investigate the backmixing characteristics of a bubble column with SVTs. In the present work, a multipoint tracer injection and detection device was employed to enhance the insight into where and how the liquid tracer was backmixed in different stages of a 50-cm diameter column. Tracer response profiles were measured to track the liquid backmixing trajectory in different stages at various operating conditions. The results showed that the backmixing of the column was sensitive to the throat diameter of SVTs. Based on the observed physical phenomena, a tanks-in-series with backflow (TISB) model was adopted to interpret the tracer experiment data, which shows an excellent agreement between the prediction and experimental measurements. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26184951 [article] Backmixing characterization of a bubble column with short venturi throats by multipoint internal tracer injections [texte imprimé] / Zi-Bin Huang, Auteur ; Zhen-Min Cheng, Auteur ; Jian-Ding Chen, Auteur . - 2012 . - pp. 9733-9741. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9733-9741 Mots-clés : Tracers  Venturi  Bubble  column  Backmixing Résumé : In reduction of liquid backmixing in bubble columns, Wu et al. [Wu, Y; Cheng, Z. M.; Huang, Z. B. Backmixing reduction of a bubble column by interruption of the global liquid circulation. Ind. Eng. Chem. Res. 2009, 48, 6558― 6563] have shown that the backmixing could be substantially reduced by interrupting the global liquid circulation using four identical short Venturi throats (SVTs). Considering the advantages of such structures, it is necessary to further investigate the backmixing characteristics of a bubble column with SVTs. In the present work, a multipoint tracer injection and detection device was employed to enhance the insight into where and how the liquid tracer was backmixed in different stages of a 50-cm diameter column. Tracer response profiles were measured to track the liquid backmixing trajectory in different stages at various operating conditions. The results showed that the backmixing of the column was sensitive to the throat diameter of SVTs. Based on the observed physical phenomena, a tanks-in-series with backflow (TISB) model was adopted to interpret the tracer experiment data, which shows an excellent agreement between the prediction and experimental measurements. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26184951

Backmixing reduction of a bubble column by interruption of the global liquid circulation / Yang Wu in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6558–6563 Titre : Backmixing reduction of a bubble column by interruption of the global liquid circulation Type de document : texte imprimé Auteurs : Yang Wu, Auteur ; Zhen-Min Cheng, Auteur ; Zi-Bin Huang, Auteur Année de publication : 2009 Article en page(s) : pp. 6558–6563 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Backmixing  reduction  Bubble  column  Lliquid  circulation  route Résumé : The strong backmixing of the liquid phase which is prevalent in a bubble column should be ascribed to its global circulation which is upward in the central region while downward near the wall on the reactor scale. To suppress the backmixing behavior, interruption of the liquid circulation route should be effective. To verify this presumption, an investigation was conducted with a bubble column 550 cm in height and 50 cm in diameter, which was equipped with four channels of the same size installed at different heights so as to cut the downward motion of the liquid and therefore prevent the global circulation the liquid. It shows that although the radial velocity distribution of the liquid remains parabolic in the short column constituted by two neighbor channels, the velocity profile tends to be flat in the upward direction as the channel is approached. The residence time distribution analysis shows that the backmixing of liquid could be reduced by 60% when four channels 12 cm in diameter were applied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900128j [article] Backmixing reduction of a bubble column by interruption of the global liquid circulation [texte imprimé] / Yang Wu, Auteur ; Zhen-Min Cheng, Auteur ; Zi-Bin Huang, Auteur . - 2009 . - pp. 6558–6563. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6558–6563 Mots-clés : Backmixing  reduction  Bubble  column  Lliquid  circulation  route Résumé : The strong backmixing of the liquid phase which is prevalent in a bubble column should be ascribed to its global circulation which is upward in the central region while downward near the wall on the reactor scale. To suppress the backmixing behavior, interruption of the liquid circulation route should be effective. To verify this presumption, an investigation was conducted with a bubble column 550 cm in height and 50 cm in diameter, which was equipped with four channels of the same size installed at different heights so as to cut the downward motion of the liquid and therefore prevent the global circulation the liquid. It shows that although the radial velocity distribution of the liquid remains parabolic in the short column constituted by two neighbor channels, the velocity profile tends to be flat in the upward direction as the channel is approached. The residence time distribution analysis shows that the backmixing of liquid could be reduced by 60% when four channels 12 cm in diameter were applied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900128j

Determination of liquid multiscale circulation structure in a bubble column by tracing the liquid flowing trajectory / Zi-Bin Huang 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. 11843-11852 Titre : Determination of liquid multiscale circulation structure in a bubble column by tracing the liquid flowing trajectory Type de document : texte imprimé Auteurs : Zi-Bin Huang, Auteur ; Zhen-Min Cheng, Auteur Année de publication : 2011 Article en page(s) : pp. 11843-11852 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Bubble  column Résumé : To identify the liquid circulation flow structure in a bubble column, a set of multipoint tracer injection and detection device was developed for a systematic study in a bubble column of 550 cm in height and 50 cm in diameter. Tracer response profiles were measured to track the liquid flowing trajectory under various flow conditions in the column with and without draft tubes. They showed that only when the draft tube length was greater than 3 m could the tracer response exhibit obvious periodicity. To resolve the liquid circulation flow structure in the time and frequency domain, wavelet multiresolution analysis was adopted. The results showed that the liquid circulation frequency increased with superficial gas velocity, which is in agreement with the published literature. It was also found that the macroscale, mesoscale, and microscale circulation loops coexisted in the bubble column. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697500 [article] Determination of liquid multiscale circulation structure in a bubble column by tracing the liquid flowing trajectory [texte imprimé] / Zi-Bin Huang, Auteur ; Zhen-Min Cheng, Auteur . - 2011 . - pp. 11843-11852. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11843-11852 Mots-clés : Bubble  column Résumé : To identify the liquid circulation flow structure in a bubble column, a set of multipoint tracer injection and detection device was developed for a systematic study in a bubble column of 550 cm in height and 50 cm in diameter. Tracer response profiles were measured to track the liquid flowing trajectory under various flow conditions in the column with and without draft tubes. They showed that only when the draft tube length was greater than 3 m could the tracer response exhibit obvious periodicity. To resolve the liquid circulation flow structure in the time and frequency domain, wavelet multiresolution analysis was adopted. The results showed that the liquid circulation frequency increased with superficial gas velocity, which is in agreement with the published literature. It was also found that the macroscale, mesoscale, and microscale circulation loops coexisted in the bubble column. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697500

Regulation of catalytic reaction via vapor - phase condensation. 1. / Ye-Mao Yu in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8735–8741 Titre : Regulation of catalytic reaction via vapor - phase condensation. 1. : Experimental study on the reaction rate hysteresis loops Type de document : texte imprimé Auteurs : Ye-Mao Yu, Auteur ; Zhen-Min Cheng, Auteur ; Zhi-Ming Zhou, Auteur Année de publication : 2012 Article en page(s) : pp. 8735–8741 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Regulation  catalytic  reaction Résumé : To experimentally verify the existence of reaction rate hysteresis in the gas phase operation due to capillary condensation, benzene hydrogenation was carried out in a fixed bed under isothermal condition. Through changing the flow rate of benzene and cyclohexane mixture in a sequence from low to high and then vice versa, a group of distinctive conversion profiles was obtained. By plotting the reaction rate against the relative vapor pressure, hysteresis loops in reaction rate are confirmed to exist. It was observed the reaction rate kept nearly constant in the region of p/p0 < 0.6 and decreased rapidly in the region of p/p0 > 0.8. In providing an intrinsic understanding on the influence of vapor condensation on the reaction rate of a partially wetted catalyst, the reaction rate and internal effectiveness factor are plotted against the catalyst wetting fraction, from which a new correlation between the overall reaction rate and catalyst wetting fraction was proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201901z [article] Regulation of catalytic reaction via vapor - phase condensation. 1. : Experimental study on the reaction rate hysteresis loops [texte imprimé] / Ye-Mao Yu, Auteur ; Zhen-Min Cheng, Auteur ; Zhi-Ming Zhou, Auteur . - 2012 . - pp. 8735–8741. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8735–8741 Mots-clés : Regulation  catalytic  reaction Résumé : To experimentally verify the existence of reaction rate hysteresis in the gas phase operation due to capillary condensation, benzene hydrogenation was carried out in a fixed bed under isothermal condition. Through changing the flow rate of benzene and cyclohexane mixture in a sequence from low to high and then vice versa, a group of distinctive conversion profiles was obtained. By plotting the reaction rate against the relative vapor pressure, hysteresis loops in reaction rate are confirmed to exist. It was observed the reaction rate kept nearly constant in the region of p/p0 < 0.6 and decreased rapidly in the region of p/p0 > 0.8. In providing an intrinsic understanding on the influence of vapor condensation on the reaction rate of a partially wetted catalyst, the reaction rate and internal effectiveness factor are plotted against the catalyst wetting fraction, from which a new correlation between the overall reaction rate and catalyst wetting fraction was proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201901z

Regulation of Catalytic Reaction via Vapor-Phase Condensation. 2. / Si-Cao Wu in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8742–8747 Titre : Regulation of Catalytic Reaction via Vapor-Phase Condensation. 2. : Operational Realization in a Two-Stage Reactor Type de document : texte imprimé Auteurs : Si-Cao Wu, Auteur ; Zhen-Min Cheng, Auteur ; Peng Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 8742–8747 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Regulation  catalytic  reaction  Vapor  phase Résumé : A two-stage reactor composed of a slurry bubble column and a fixed bed was proposed. The slurry column, installed with a radio frequency conductance liquid level controller, was considered not only as a preliminary reactor for the vaporization of the liquid reactants, but also as a protector to prevent liquid flooding in the fixed bed. Preliminary experiments were carried out to investigate the effects of different operating factors on the reactor performance, and the results showed that even under the optimal condition the benzene concentration should be kept at a low level of 21.9% to avoid high temperature rise. Therefore, side stream injection of cyclohexane into the fixed bed was proposed, and benzene conversion of 99.82% was reached even at a much higher concentration of 32.8%. To verify whether capillary condensation inside the catalyst particle in the fixed bed would exist in the presence of coolant injection, a criterion was proposed which is based on the understanding that once vapor condensation is occurring it will lead to multiplicity in reaction rate, which will consequently result in hysteresis in temperature profile under adiabatic condition. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2019036 [article] Regulation of Catalytic Reaction via Vapor-Phase Condensation. 2. : Operational Realization in a Two-Stage Reactor [texte imprimé] / Si-Cao Wu, Auteur ; Zhen-Min Cheng, Auteur ; Peng Liu, Auteur . - 2012 . - pp. 8742–8747. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8742–8747 Mots-clés : Regulation  catalytic  reaction  Vapor  phase Résumé : A two-stage reactor composed of a slurry bubble column and a fixed bed was proposed. The slurry column, installed with a radio frequency conductance liquid level controller, was considered not only as a preliminary reactor for the vaporization of the liquid reactants, but also as a protector to prevent liquid flooding in the fixed bed. Preliminary experiments were carried out to investigate the effects of different operating factors on the reactor performance, and the results showed that even under the optimal condition the benzene concentration should be kept at a low level of 21.9% to avoid high temperature rise. Therefore, side stream injection of cyclohexane into the fixed bed was proposed, and benzene conversion of 99.82% was reached even at a much higher concentration of 32.8%. To verify whether capillary condensation inside the catalyst particle in the fixed bed would exist in the presence of coolant injection, a criterion was proposed which is based on the understanding that once vapor condensation is occurring it will lead to multiplicity in reaction rate, which will consequently result in hysteresis in temperature profile under adiabatic condition. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2019036