A Numerical Approach on Waste Heat Recovery through Sidewall Heat-Exchanging in an Aluminum Electrolysis Cell

This paper proposes a technical viewpoint for the recovery of waste heat in aluminum electrolysis. The idea of combining heat-generating electrolysis process and the heat-consuming alumina tube digestion process is discussed in detail. The structural design of the heat-exchanging system as well as the matching problems between the heat exchanger and cell design are also mentioned. Several major concerns including the automatic temperature regulation of the cell sidewall and the preferred selection principles for the heat medium are introduced. A 2 kA heat exchangeable cell is developed and a series of tests are carried out in the laboratory. It is found that approximate 80% of the sidewall waste heat can be recovered while the cell behaves steadily. It is also proved possible to control the thickness of the frozen ledge through adjusting the heat convection rate of the heat exchanger. The heat-exchanging system is also suitable for aluminum cells when the fluctuating wind power is applied as a major energy supply.