AN EXPERIMENTAL AND THEORETICAL STUDY OF THE HYDRODYNAMIC EFFECT OF GAS-LIQUID-SOLID VERTICAL UPFLOW SYSTEMS (FLOW REGIMES, GAS HOLDUP)

The objective of this project was to experimentally study the hydrodynamics of three phase gas-liquid-solid vertical upflow at various solids concentrations in two different test columns. The effect of solids concentration on flow regime transitions and average gas holdup was studied using air, water, and 40 - 80 (mu)m glass beads in a 5 cm ID and 14 cm ID Plexiglass test column.; Several simple models to predict the bubble to bubble-slug, bubble-slug to slug, and slug to churn flow transitions were developed utilizing criteria proposed for gas-liquid vertical flow. These criteria were shown to apply equally well in the absence or presence of the solid phase. The solid phase was found to affect the location at which bubble to bubble-slug and the bubble-slug to slug flow transitions occurred. However, the slug to churn flow transition was unaffected by the presence of the solid phase.; The effect of solids concentration was found to have a dual influence on gas holdup. At low slurry superficial velocities, the gas holdup decreased with increasing solids concentration. However, at high slurry superficial velocities, the gas holdup increased with increasing solids concentration. These results indicate that the presence of solid particles affects the rate of bubble coalescence as well as the turbulent forces of the liquid phase.; The gas holdup data obtained in this study were analyzed using a modified form of the drift velocity model. This analysis accounted for the nonuniform radial distribution of gas holdup, gas velocity and slurry velocity as well as the "slip" effect between the phases. The gas holdup data, correlated using this analysis, were within (+OR-)15% of the experimental observations for all solids concentrations and flow regimes studied.; A hydrodynamic model was developed for the bubble flow regime which utilized a solution to the time averaged Navier-Stokes equations coupled with the drift velocity phase relationships. The model predicted gas holdups which were within (+OR-)15% of the experimental values obtained in the 14 cm ID test column at each solids concentration.