Numerical modelling of mass transfer in an autoclave

• First compartment of an autoclave was modelled using CFD.
• CFD models predicting gas-liquid mass transfer were validated using experimental data.
• Gas-liquid mass transfer distribution displayed unusual characteristics and were uneven, asymmetric as well as low.

This paper investigates the numerical modelling of mass transfer in the first compartment of an autoclave. A scaled down model of an 80 m3 Sherritt Gordon horizontal autoclave agitated by a Smith turbine was used. The commercial code, ANSYS Fluent 13 was used for the CFD simulations. Gas–liquid mass transfer, kLa was modelled and validated against experimental data. The distribution of gas–liquid mass transfer was found to be poor as a result of the flow pattern and gas dispersion. The effect of operating conditions on kLa was found to be similar as observed in mixing vessels, that is increasing with impeller speed, gas flow-rate and temperature. An empirical correlation based on experimental data was also developed to estimate mass transfer.