Numerical Investigation of Turbulent Diffusion Flame in the Aluminum Anode Baking Furnace Employing Presumed PDF

A modern aluminum smelter has a capacity of 1-2 million tons of aluminum per annum which requires more than 0.5-1.0 million tons of heat treated (baked) carbon anodes per year. Anode baking homogeneity strongly depends on flow distribution in the flue wall cavity which consists of several baffles with certain geometrical design. Moreover, fuel consumption and pollutants emissions are major concerns in the aluminum anode baking furnace (ABF). In the numerical modeling of the turbulent reactive flows, the accuracy of the model highly depends on the description of turbulence-chemistry interaction (TCI). Hence, the present study tested different TCI frameworks for confined diffusion flames and results are compared the results with the reported numerical and experimental data in the literature. It was observed thatk - ϵ realizable turbulence model combined with presumed probability density function (PDF) method shows an excellent agreement with the experimental data. The developed numerical framework was employed to investigate the effects of flue wall design modification on combustion and emissions characteristics of ABF. It is observed that by closing the openings at the top of the baffles, the same average flue gas temperature can be obtained by reducing the global equivalence ratio (φ_glob) from 1.0 to 0.125. Lower φ_glob value results in a lower fuel consumption which consequently translates into less CO, NOx and soot concentration.