Engineering Solutions for Cooling Aluminum Electrolyzer Exhaust Gases

Abstract

During aluminum production by self-fi ring anode technology, complete combustion of anode gas components (carbon monoxide, resin substances) is accomplished in electrolyzer burner units. With the aim of reducing combustion product temperature entering the gas conduit network of the electrolyzer body, air is fed into a burner unit in excess (α = 6). This amount considerably exceeds that recommended for burning gaseous fuel. As a result of the excessive air intake, excess air the temperature in the combustion zone may be reduced to 300°C. Unburned resin substance is carried with this into the gas exhaust system that is cooled, condensed, and together with dust particles contained in transported anode gases, is deposited on the walls of gas conduits reducing their useful cross section. An improvement in anode gas fuel component complete combustion by optimizing excess air within the limits of α = 1.5–1.2 provides a temperature within the combustion zone within the limits of 1270–1330°C. However, in the process the temperature of combustion products entering from a burner into the gas circuit increases to 1000°C and above, and this is connected with the risk of irreversible deformation of steel gas conduits and melting of gas cleaning unit (GCU) bag filters whose permissible operating temperature is in the range 140–160°C. Engineering solutions are proposed in this article aimed at providing safe operation of gas conduit circuits and electrolysis housing GCU with increased efficiency for burning resin substances in electrolyzer burner units.