CFD analysis of the intensification mechanism of bubble breakup by perforated plates in a bubble column

Abstract

Conventional bubble column reactors suffer from some drawbacks like severe backmixing and poor heat/mass transfer performance. The process intensification by the utilization of perforated plates has been an important strategy to overcome these problems. However, a fundamental understanding of the bubble breakup by perforated plates is still very limited. CFD simulations are carried out to reveal the interaction between the rising bubbles and perforated plates. It is found that no bubbles break up when they just pass through the hole. A bubble can be broken into three small daughter bubbles when it collides with the bridge connecting three holes. The bubble breakup is mainly attributed to the bridge cutting, whereas it is not sensitive to large hole diameters. A large bubble cap is formed underneath the plate due to very small hole diameter. The plate thickness has no significant influence on bubble breakup. When the inclined angle of a perforated plate is larger than 45°, the bubbles slide beneath the plate more readily and no bubbles pass through it. The perforated plate with large inclined angle fails to induce bubble breakup. This study would provide deep insights into bubble breakup mechanism related to process intensification by perforated plates.