Heat recovery from aluminium reduction cells

Abstract

About half of the energy spent in aluminium electrolysis is lost as heat. A preliminary study concerning the possibilities of recovering part of that heat was carried out, primarily focusing on electrical power production. The three main heat sources (cathode sides, anode yokes, and gas) were combined in different ways, using different types of power cycles. The potential for electric power production is significant (up to 9 percent of the total consumption). The two most promising families of power cycles appear to be 1) distributed open Brayton cycle based on a turbo charger and 2) centralised power production with a Rankine cycle. The temperature and amount of heat available in the anode match well with the heat from the sides, while the potential of integrating the flue gas is limited. The main aims in energy recovery may be increased productivity or reduced energy consumption, which gives different strategies for heat collection.