CFD Prediction of Odour Dispersion and Plume Visibility for Alumina Refinery Calciner Stacks

Computational fluid dynamics (CFD) models are developed to examine the behaviour of moisture-laden buoyant plumes emitted from Alumina refinery calciner stacks. The CFD modelling is carried out to complement traditional atmospheric dispersion modelling undertaken as part of a study to develop odour reduction strategies for Alcoa's Wagerup refinery in Western Australia. The commercial package CFX-4.4 is used to develop a plume model which incorporates source terms for condensation, evaporation and associated heat transfer. The model is used to examine issues that cannot be assessed with standard atmospheric dispersion models, such as the impact of condensation on plume rise and ground-level odour and the impact of ambient air addition on plume visibility. A second model developed in the commercial package CFX-5.5 is used to examine the potential to reduce ground-level odour through the construction of a 100 m high multiflue stack. Solution-adaptive meshing is used to reduce initial model set-up time and to optimize the mesh size in regions of high concentration gradients. The relationship between the CFD models developed and traditional atmospheric dispersion models is discussed and the paper illustrates how the different techniques can be used in a complimentary fashion to develop engineering solutions to reduce the impact of emissions from an industrial plant.