Dense phase viscosities of fluidised beds at elevated pressures

Abstract The dense phase viscosities of gas-fluidised beds have been measured at pressures up to 20 bar by a falling-sphere technique. Glass powders of mean sizes 64, 101 and 475 μm were fluidised by carbon dioxide or nitrogen. An increase in gas pressure leads to a substantial decrease in the viscosity of the fine powder when fluidised but the viscosity of fluidised beds of powders larger than about 100 μm is almost independent of pressure. The implications of the experimental observations on the stability of bubbles in high-pressure fluidised beds are discussed.