Numerical modelling of hydrodynamics and gas dispersion in an autoclave

This paper investigates the numerical modelling of hydrodynamics and gas dispersion in the first compartment of an autoclave. A scaled down model of an 80 m3 Sherritt Gordon horizontal autoclave agitated by a radial Smith turbine was used. The CFD simulations were implemented using the commercial code, ANSYS Fluent 13. The CFD model was validated using experimentally determined power draw, velocity flow field and bubble size data. Hydrodynamics and gas dispersion displayed unusual characteristics compared to conventional stirred tanks. Fluid flow leaving the impeller was found to have a negative inclination to the horizontal. Mixing was found to be asymmetric and non-ideal. Gas dispersion was found to be relatively poor, non-homogeneous with accumulation of oxygen gas below the impeller, asymmetric and with low gas hold-ups.

► First compartment of an autoclave was modelled using CFD.
► CFD models were validated using experimental data.
► Hydrodynamics and gas dispersion displayed unusual characteristics.
► Fluid flow leaving impeller was found to have a negative inclination to horizontal.
► Gas dispersion was poor, with low gas hold-ups.