Mass transfer and liquid mixing in an airlift reactor with a net draft tube

Mass transfer and liquid mixing in an airlift reactor with a net draft tube were experimentally investigated. Four different column diameters were considered. The mass transfer was measured using the volumetric gas-liquid mass transfer coefficient which was determined by the dynamic method. The mass transfer coefficients in the airlift reactors with different column diameters were not always higher than those in the bubble columns. The liquid mixing was measured using mixing time which was determined by a pulse technique. Under the same superficial gas velocity, the mixing times of the airlift reactors with a net draft tube were always less than those of the bubble columns.List of Symbols C mol·dm^–3 bulk concentration of dissolved oxygen - C ₀ mol·dm^–3 initial concentration of dissolved oxygen - C _e mol·dm^–3 saturated concentration of dissolved oxygen - ¯C dimensionless dissolved oxygen concentration - D _c cm diameter of column - D _N cm diameter of the nozzle hole - D _T cm diameter of the net draft tube - H _L cm static liquid height - H _T cm height of the net draft tube - k _L a hr^–1 volumetric mass transfer coefficient - L _T cm length of the net draft tube - t _M sec mixing time of the liquid phase - t ₀ sec mixing time of the liquid phase in a bubble column - V _L dm³ volume of the liquid phase - U _g cm/s superficial air velocity