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.