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Cylindrical Column (cylindrical + column)
Selected AbstractsMicrowave regeneration of zeolites in a 1 meter columnAICHE JOURNAL, Issue 7 2009Matthias Meier Abstract Although sorption is a common method of removing volatile organic compounds (VOC's) from processes, the adsorbent must be regenerated to repeat the process. The use of microwaves to regenerate the bed of adsorbent can be more efficient than conventional heating methods. Desorption of methanol from a silicalite zeolite was studied by the use of microwaves in cylindrical column. Temperature probes at five axial and three radial positions monitored the temperature profile in time. A significant amount of microwave energy passed through the dry zeolite bed, whereas a strong attenuation occurs if methanol is adsorbed. The radial temperature distribution conforms to theoretical predictions; however, microwave reflections cause a distortion of the predictions in the axial direction. Irregularities during the saturation of the bed indicated a chemical reaction during the irradiation with microwaves. A fraction of the methanol reacted under microwave irradiation to form dimethylether and water, and to methoxylate the zeolite surface. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Study on conical columns for semi-preparative liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3-4 2003Ma Jiping Abstract The dynamic flow profiles and column efficiencies in conically shaped semi-preparative liquid chromatographic columns (inlet ID larger than outlet ID) with two different conical angles (7° and 15°) were studied. The dynamic flow profiles were studied by an on-column visualization method. Conical columns were compared with cylindrical column of the same length and internal volume. The results showed that the flow profile of a sample band in the conical column of 7° (50 mm×17 mm , 11 mm ID) was parabolic in shape. The sample band migrated slower in the wall region than in the central region, as in the cylindrical column (50 mm×14 mm ID). However, the sample band in the conical column of 15° (50 mm×20 mm , 7 mm ID) migrated slower in the central region than in the wall region, resulting in a reverse parabolic flow profile, in contrast to that in cylindrical column. This indicated that a flat flow profile might be realized in a conical column with a conical angle between 7° and 15°. The conical column of 15° had the highest column efficiency among the three columns under the same conditions. Compared with the cylindrical column packed with identical packing material, the conical column of 15° had 22%,45% higher column efficiency and 11%,27% higher peak height. [source] Hydrodynamic Characteristics of a Powder-Particle Spouted Bed with Powder Entrained in Spouting GasTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2005Qunyi Zhu Abstract Spouting of 3.7 mm polyvinyl chloride particles in a cone-based cylindrical column is subjected to entrainment of FCC powder in the spouting air. It is found that the powder entrainment reduces the minimum spouting velocity, increases the bed pressure drop and reduces the maximum spoutable bed height. At any given bed height and value of U/Ums, there is a critical value of powder loading ratio above which spouting gives way to slugging. Le jaillissement de particules de chlorure de polyvinyle dans une colonne cylindrique à base conique a été soumis à un entraînement de poudre de FCC dans l'air jaillissant. On a trouvé que l'entraînement de poudre réduisait la vitesse de jaillissement minimale, augmentait la perte de charge de lit et réduisait la hauteur maximum de lit jaillissant. À toute hauteur de lit et valeur de U/Ums données, il existe une valeur critique du rapport de charge de poudre au-dessus duquel le jaillissement conduit au pistonnage. [source] Mathematical model for mixing index in gas,solid fluidized bed: an analysisASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Abanti Sahoo Abstract An available theoretical model for mixing index in gas-solid fluidized bed has been analyzed for further modification and improvement. Assumption of 50% bed material moving in the upward direction and rest 50% in the downward direction considered for the above model (the counter-flow circulation model) has been analyzed for optimum result. A computer program was run for different bed conditions by varying operating parameters, namely, the mixture composition, fractions of bed materials, minimum fluidization velocity of the jetsam particles and that of the bed materials (i.e. mixture of the jetsam and the flotsam particles). The developed model was solved by finite difference (central differencing). Fraction of the bed material moving in the upward direction was varied from 0 to 100% and the minimum fluidization velocity was varied within the Umf of the flotsam to that of the jetsam particles (i.e. 0.465,1.0335 m/s). Optimum fraction of bed materials with respect to its distribution (as per the earlier proposed model) in the upward and downward streams during the fluidization process was found to be 20 and 80%, respectively. The modified model was validated by conducting experiments on fluidization and studying the mixing characteristics of regular homogeneous materials (sago) in a 15 × 100 cm cylindrical column. Fairly good agreement was observed between the values of mixing index obtained from the proposed modified model and the experimental observations. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Exploring a non-dimensional varying exponent equation relating minimum spouting velocity to maximum spoutable bed depthTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Wei Du Abstract The equation was critically examined for spouting both in small conical-cylindrical columns (Dc,<,0.5 m) and large cone-base or flat-bottom cylindrical columns (Dc,,,0.5 m). For small columns, a data base of 36 points with experimental measurements of both Hm and Um(=Ums at H,=,Hm) afforded some insights into the components of this equation and to the merits of the equation itself. For large columns, in the absence of verifiable methods of predicting Hm, correlation of Ums/Umf as a function of H/Hm, using the available experimental data on Ums, has not been achieved. L'équation a été examinée de manière critique pour le jaillissement dans de petites colonnes coniques et cylindriques, (Dc,<,0.5 m) et de larges colonnes cylindriques à base conique ou à fond plat, (Dc,,,0.5 m). Pour les petites colonnes, une base de données de 36 points composée des mesures expérimentales de Hm et Um (,=,Ums at H,=,Hm) a permis de mieux comprendre les composantes de cette équation et la qualité de l'équation elle-même. Pour les colonnes plus larges, en l'absence de méthodes vérifiables pour prédire Hm, la corrélation de Ums/Umf en fonction de H/Hm, à l'aide des données expérimentales disponibles sur Um, n'a pu être établie. [source] | ||||||||||