Investigating the Influence of the Configuration of the Bundle of Heat Exchanging Tubes and Column Size on the Gas Holdup Distributions in Bubble Columns Via Gamma-Ray Computed Tomography
The impact of dense vertical internal tubes and their configurations on the gas holdup distributions and their diametrical profiles in pilot-scale bubble column is visualized and quantified for the first time ever using an advanced gamma-ray computed tomography (CT) technique. Two arrangements of vertical internals (circular and hexagonal configurations) occupying the same cross-sectional area (CSA) of the column (about 25% of the total cross-sectional area to represent the heat exchanging tubes that are used in the Fischer-Tropsch synthesis), were examined in addition to the measurement in the bubble column without vertical internals. Moreover, the gas holdup distribution results of the 18-inch (0.46 m in outer diameter, O.D.) bubble column are compared with an available data of 6-inch (0.15 m in O.D.) bubble columns with and without vertical internals. CT scans have been conducted for 18-inch bubble columns with and without vertical internals for the air-water system under a wide range of superficial gas velocity (0.05-0.45 m/s). The experimental results indicate that an improvement in the gas holdup distribution over the column's cross-sectional area is obtained when the vertical internal tubes (arranged in either a circular or a hexagonal configuration) were used. However, better cross-sectional gas holdup distribution was achieved in the bubble column with vertical internals arranged in a hexagonal configuration as compared to the bubble column without and with vertical internals arranged in a circular arrangement. Additionally, the averages of the cross-sectional gas holdup and their profiles for bubble column with and without vertical internals are close to each other when the bubble column with vertical internals is operating at a high superficial gas velocity, which is calculated based on the free cross-sectional area for the flow. Furthermore, the gas holdup distributions are further improved when the larger bubble column with vertical internals was used as compared to the 6-inch bubble columns with and without vertical internals.
A. J. Sultan et al., "Investigating the Influence of the Configuration of the Bundle of Heat Exchanging Tubes and Column Size on the Gas Holdup Distributions in Bubble Columns Via Gamma-Ray Computed Tomography," Experimental Thermal and Fluid Science, vol. 98, pp. 68-85, Elsevier, Nov 2018.
The definitive version is available at https://doi.org/10.1016/j.expthermflusci.2018.05.005
Chemical and Biochemical Engineering
Keywords and Phrases
Computed Tomography (CT); Configurations of Vertical Internals; Gas Holdup Distribution; Pilot-Scale Bubble Column; Vertical Internal Tubes
International Standard Serial Number (ISSN)
Article - Journal
© 2018 Elsevier, All rights reserved.
01 Nov 2018