Thermal effects by anode changing in prebake reduction cells

Abstract

Thermal effects caused by anode changing in prebake alumina reduction cells were studied by temperature measurements using thermocouples located at different positions inside the anodes. Anode changing caused a temperature reduction in the nearest neighbour anode of typically 20 to 40°C, as measured close to its working surface. The minimum temperature was recorded about 5 hours after the anode change, and it could take up to 24 hours before the old anode again showed a stable temperature reading. The cooling effect is due to heat radiation losses to the new anode, and thus the heat balance of the neighbouring anodes is altered significantly after an anode change. Temperatures were also measured inside the newly set anode. If the new anode on purpose was set too low by 20 mm to provoke formation of a spike on the working surface, the measured temperature inside this anode could reach as high as 1080 °C.