Mass transfer in highly viscous liquids in a bubble column with constant-flow nozzles

Bubble columns with constant-flow nozzles were used to obtain high values of gas holdup e and volumetric mass transfer coefficient k_La for highly viscous liquids at relatively low gas-flow rates. Effects of various factors on £, k_La, mass transfer coefficient k_L, bubble volume V_Bformed at constant-flow nozzle, and gas-liquid interfacial area a were investigated experimentally. Liquid viscosity, superficial gas velocity, number of constant-flow nozzles and pitch affected e, k_La, k_L, V_Band a. The experimental results were correlated by dimensionless equations, which were compared with previous works. For a given energy input, a in this bubble column was larger than that in conventional bubble columns with a perforated plate as gas distributor.