An experimental study was performed to investigate the effect of sieve trays on the time-averaged gas holdup profiles and the overall gas holdup in a cold-flow bubble column that was scaled-down from a commercial unit. γ-ray computed tomography (CT) was used to scan the column at several axial locations in the presence and absence of trays from which the local variation of the gas holdup was extracted. The overall gas holdup was also determined using the same configuration by comparing the expanded and static liquid heights. Air and water were used as the gas-liquid system. The superficial gas and liquid velocities were selected to span the range of the commercial system using gas spargers having multiple lateral distributors that were also scaled-down from the commercial design. To investigate the impact of sparger hole density on the local and overall gas holdup, two difference sparger designs were used in which the hole density per lateral was varied. The gas hole velocity was maintained constant at ca. 245 m/s, which approached that used in the commercial reactor. It is shown that the local gas holdup determined by CT is generally higher in the tray down comer region and exhibits an asymmetric pattern when trays are present. The use of increased sparger hole density at a constant gas superficial velocity leads to steeper gradient in the gas holdup near the column centerline and a higher overall gas holdup. These findings suggest that the performance of bubble column reactors for various applications is sensitive to both sparger and tray design.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering