Effect of electrostatics on interaction of bubble pairs in a fluidized bed

• The effect of electrostatics on interaction of bubble pairs is investigated.
• The model predicts the pattern of bubble coalescence seen in the experiments.
• Coalescence of a vertically-aligned bubble pair results in a larger resultant bubble.
• Electrostatics can modify leading–trailing role of bubbles in horizontal alignment.

Electrostatic charges can influence the hydrodynamics of gas–solid fluidized beds. In our previous work (Jalalinejad et al., 2012), it was shown that high charge density modified the single bubble shape in fluidized beds. In this study, we investigate the effect of electrostatics on interaction of bubbles by simulating pairs of bubbles in vertical and horizontal alignment in uncharged and charged particles. The geometry simulated is based on the experiment of Clift and Grace (1970), with simulation results compared with their experiments for bubbles in vertical alignment. The model predicts the overall coalescence pattern, but the trailing bubble splits in simulations, unlike experiment.The effect of electrostatics is modeled by solving electrical equations and adopting the Two Fluid Model in MFIX (an open source code). Comparison of uncharged and charged cases for bubbles in vertical alignment shows different bubble coalescence behaviour, with greater asymmetry in the charged case, leading to larger resultant bubble. For bubbles in horizontal alignment, electric charges cause the side bubble to migrate towards the axis of the column, reversing the leading-trailing role of the two bubbles, which led to the decrease in the height of complete coalescence.

Figure optionsDownload as PowerPoint slide