Study of Liquid Weeping at a Tapered Orifice in a Bubble Column Reactor by a Computer-Aided Image Analysis Algorithm

Abstract

Understanding the phenomenon of liquid weeping requires knowledge of the bubbling and weeping cycle. Hence, an image analysis algorithm is developed and subsequently coupled with high-speed imaging techniques to examine the different stages in the bubbling and weeping cycle automatically. The bubbling and weeping cycle is studied under various operating conditions, using the developed algorithm, coupled with high-speed imaging techniques and the pressure fluctuation measurement. The effect of orifice angle (where the orifice angle is a measure of the orifice taperness) on the liquid weeping rate is evaluated over a range of superficial orifice gas velocities and justified with the aid of the developed algorithm, coupled with high-speed imaging techniques. A gas distributor plate with negative angle orifices is recommended for improved operation of industrial bubble column reactors over the range of superficial orifice gas velocities considered in this study, because it substantially decreases the liquid weeping rate.

Mass transfer studies in shallow bubble column reactors

“…Since the orifice size of the perforated plate is large, low pressure drop across the 11 distributor is present. The bubble formation process can generate substantial pressure fluctuation in the plenum [5,29]. The variation in k L is likely due to the uneven distribution of bubbles caused by the substantial pressure fluctuation at the plenum.…”

Effects of Orifice Angle and Surface Roughness on the Bubbling-to-Jetting Regime Transition in a Bubble Column

“…A study of liquid weeping at a single orifice reported that orifice angles between 0 and π/2 generate higher liquid weeping rates than an orifice angle equal to 0 . A high weeping rate is directly associated with a high regime-transition velocity.…”

“…Bubbling and liquid weeping occur simultaneously, and no bridging stage is observed. As a result, gas is present at the orifice at all times . The occasional presence of liquid weeping essentially reduces the effective orifice diameter and, in turn, causes regime transition to occur at a lower gas velocity.…”

“…Few studies have taken into account the effects of the surface roughness of the orifice and the orifice angle on the regime transition. Both orifice surface roughness and orifice angle were found to have significant impacts on the liquid weeping rate in previous studies. , It is highly possible that the two parameters will also affect the bubbling/jetting regime transition.…”

“…Both orifice surface roughness and orifice angle were found to have significant impacts on the liquid weeping rate in previous studies. 13,14 It is highly possible that the two parameters will also affect the bubbling/jetting regime transition.…”