Enhanced mass transfer from the installation of a sieve tray subject to the variation of liquid heights and flow regimes in a bubble column

Abstract

This work addressed the gas–liquid (G/L) mass transfer limitation coming from the increasing liquid height and the circumvention of the limitation by introducing a sieve tray in a bubble column. Either monoethylene glycol (MEG) solution or n-hexane was adopted as a liquid phase and argon was used as a gas phase in the bubble column. The gas holdup and the mass transfer coefficient became lowered by the static liquid height increase due to the increase of bubble size. The loss of mass transfer was overcome by installing a sieve tray inside the column. The two sieve trays with different hole sizes were employed and both bubble diameter and standard deviation of pressure were investigated to understand the effect of the sieve tray on the mass transfer. With a smaller size hole sieve (1 mm), the mass transfer deteriorated in both liquid systems (MEG and n-hexane) due to the formation of gas cap below the sieve while with a larger hole sieve (3 mm), it was enhanced because of the reduction of bubble diameters without any gas cap formation. However, it was found that the sieve tray effect was weakened when the flow regime changes from homogeneous to heterogeneous. © 2018 Institution of Chemical Engineers