Bubble characterization in a fluidized bed with vertical tubes / Martin Rüdisüli in Industrial & engineering chemistry research, Vol. 51 N° 12 (Mars 2012)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4748–4758 Titre : Bubble characterization in a fluidized bed with vertical tubes Type de document : texte imprimé Auteurs : Martin Rüdisüli, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur Année de publication : 2012 Article en page(s) : pp. 4748–4758 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidized beds Heat exchanger Résumé : Vertical tubes are commonly used in industrial fluidized beds as heat exchanger tubes. In this study, the influence of vertical tube banks on the axial bubble growth in a 145-mm inner diameter (ID) fluidized bed with Geldart B particles is experimentally investigated by means of pressure fluctuation measurement (PFM) and optical probing (OP). The employed tube bank configurations differ in their tube-to-tube spacing, tube diameter, and tube arrangement (square versus triangular). PFM and OP show that immersed vertical tube banks, irrespective of their configuration, significantly reduce the axial bubble growth. The bubble size reduction is even more significant for higher gas velocities (u0/umf > 4.6, where u0 is the superficial gas velocity and umf is the minimum fluidization velocity) as well as if the tube-to-tube spacing is narrow and the tube diameter is small. The tube arrangement (square versus triangular), in turn, does not show any significant differences. Depending on the gas velocity, the ratio of the bubble diameter to the tube diameter and the tube-to-tube spacing is changed. This change invokes a different bubble flow pattern between the vertical tubes and different bubble growth mechanism, which defines the effectiveness of vertical tubes to delay slugging and makes the fluidization smoother. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2022306 [article] Bubble characterization in a fluidized bed with vertical tubes [texte imprimé] / Martin Rüdisüli, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur . - 2012 . - pp. 4748–4758. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4748–4758 Mots-clés : Fluidized beds Heat exchanger Résumé : Vertical tubes are commonly used in industrial fluidized beds as heat exchanger tubes. In this study, the influence of vertical tube banks on the axial bubble growth in a 145-mm inner diameter (ID) fluidized bed with Geldart B particles is experimentally investigated by means of pressure fluctuation measurement (PFM) and optical probing (OP). The employed tube bank configurations differ in their tube-to-tube spacing, tube diameter, and tube arrangement (square versus triangular). PFM and OP show that immersed vertical tube banks, irrespective of their configuration, significantly reduce the axial bubble growth. The bubble size reduction is even more significant for higher gas velocities (u0/umf > 4.6, where u0 is the superficial gas velocity and umf is the minimum fluidization velocity) as well as if the tube-to-tube spacing is narrow and the tube diameter is small. The tube arrangement (square versus triangular), in turn, does not show any significant differences. Depending on the gas velocity, the ratio of the bubble diameter to the tube diameter and the tube-to-tube spacing is changed. This change invokes a different bubble flow pattern between the vertical tubes and different bubble growth mechanism, which defines the effectiveness of vertical tubes to delay slugging and makes the fluidization smoother. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2022306

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Radial bubble distribution in a fluidized bed with vertical tubes / Martin Rüdisüli in Industrial & engineering chemistry research, Vol. 51 N° 42 (Octobre 2012)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 51 N° 42 (Octobre 2012) . - pp. 13815-13824 Titre : Radial bubble distribution in a fluidized bed with vertical tubes Type de document : texte imprimé Auteurs : Martin Rüdisüli, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur Année de publication : 2012 Article en page(s) : pp. 13815-13824 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Vertical tube Fluidized bed Fluidization Bubble Résumé : The radial distribution of bubble characteristics such as the bubble frequency, the bubble size, and the bubble rise velocity, is a key to better understanding the flow patterns of gas (and solids) in bubbling fluidized beds. Therefore, the radial distribution of bubble characteristics is investigated in a fluidized bed with vertical tubes by means of optical probes. Measurements are taken for Geldart B particles at two bed heights, three gas velocities, and three vertical tube bank configurations. While the bubble frequency shows a strong dependence on the radial position in the bed and the orientation of the vertical tubes, the bubble size and the bubble rise velocity, in particular in the lower portions of the bed, are more constant. Typical bubble pathways are shown to move from the column wall to the center axis of the bed with increased bed height. Therefore, in order to have a representative mean bubble size and mean bubble rise velocity, which accounts for the whole cross-section of the bed, an area-number weighted mean is introduced. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26508205 [article] Radial bubble distribution in a fluidized bed with vertical tubes [texte imprimé] / Martin Rüdisüli, Auteur ; Tilman J. Schildhauer, Auteur ; Serge M. A. Biollaz, Auteur . - 2012 . - pp. 13815-13824. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 42 (Octobre 2012) . - pp. 13815-13824 Mots-clés : Vertical tube Fluidized bed Fluidization Bubble Résumé : The radial distribution of bubble characteristics such as the bubble frequency, the bubble size, and the bubble rise velocity, is a key to better understanding the flow patterns of gas (and solids) in bubbling fluidized beds. Therefore, the radial distribution of bubble characteristics is investigated in a fluidized bed with vertical tubes by means of optical probes. Measurements are taken for Geldart B particles at two bed heights, three gas velocities, and three vertical tube bank configurations. While the bubble frequency shows a strong dependence on the radial position in the bed and the orientation of the vertical tubes, the bubble size and the bubble rise velocity, in particular in the lower portions of the bed, are more constant. Typical bubble pathways are shown to move from the column wall to the center axis of the bed with increased bed height. Therefore, in order to have a representative mean bubble size and mean bubble rise velocity, which accounts for the whole cross-section of the bed, an area-number weighted mean is introduced. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26508205

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