The impact of cell ventilation on the top heat losses and fugitive emissions in an aluminium smelting cell

Abstract

Problems associated with aluminium smelting cell ventilation, caused by leakage of fume gases through pots superstructure gaps into the potroom, are normally solved by increasing the fume suction rate (draught) above certain levels. It is also known that, fugitive emissions are associated with reducing the draught below certain critical levels. Top heat losses are increasing in smelting cells as line amperage is raised. This drives further fugitive emissions through greater buoyancy of the fume/air mixture. A quantitative understanding of the relationship between fugitive emissions, superstructure tightness, top heat loss, and cell draught is crucial in the environmental context. It is also important if this top heat loss could be recovered for re-use. This problem is studied here computationally using the ANSYSCFX software. Possibilities to improve cell ventilation and to decrease fugitive emissions are analysed for a typical industrial cell. The computed cell emissions and temperatures are compared with measured values. The impact of draught on ventilation and heat loss is also discussed.