Developing CFD models of furnaces requires careful consideration of the key physical processes, which include the gas flow, turbulence, flow of solids particles and combustion. These processes are closely coupled and the interaction between the combustion process and feed solids must be correctly considered in order to produce a realistic simulation.

This example is a model of a furnace within an alumina flash calciner and includes heavy fuel oil combustion and the alumina calcination reaction. As the particles undergo the calcination process the chemical reaction produces water vapour and absorbs energy. Both these process have a significant effect on the gas volume and density.

By considering all the physical processes coupled together within one model, the complex behaviour of the furnace can be modelled. These furnace models greatly enhance the design process by providing the following information:

• solids feed and distribution within the furnace
• solids retention times
• calcination rates and particle composition exiting the furnace
• interaction between the combustion zone and calcination reaction
• gas distribution and effect of burner placement
• identify high temperature regions responsible for NOx production