HYDRODYNAMIC MODEL FOR GAS-LIFT REACTORS

The hydrodynamic model of Young et al. (1991) for external-loop gas-li ft reactors was modified to account for buoyancy forces in the gas pha se. The revised model is based on macroscopic balances for the gas-liq uid separator and external downcomer and spatially-averaged, I-D mass and momentum balances in the riser. Using only the physical properties of the gas and liquid phases, the reactor dimensions, and the gas sup erficial velocity the model predicts gas holdup profiles, gas and liqu id velocity profiles, and pressure profiles in the riser for bubbly fl ow. Empirical correlations are used to represent frictional and drag e ffects, but there are no adjustable parameters in the model. The syste m of equations that must be solved to predict hydrodynamic behavior is simpler than that of Young et al. The sensitivity of the model to cho ice of drag coefficient correlation is analyzed The model predictions match experimental data of previous works.