Effect of solid particles on gas hold‐up in bubble columns

The gas hold‐up in bubble columns containing fluidised plastic particles as solid phase was measured as a function of superficial gas velocity and solids concentration. The effects of particle size, density, wettability and concentration on gas hold‐up and bubble coalescence were studied. It was found that the addition of non‐wettable solids to the air/water mixture promotes bubble coalescence and, therefore, reduces the gas hold‐up, while the addition of wettable solids suppresses bubble coalescence and increases the gas hold‐up.