Improved design of the automatic alumina feeding system in a prebaked-anode electrolyzer

This study aims to improve the design of the breaker tip used in the automatic alumina feeding system of RA-550 prebaked-anode electrolyzers. We examined a thermal stabilizer constructed as a hollow rod with a tip and spiral finning, partially filled with water as the heat-transfer medium. The stabilizer was tested using a FLIR thermal imager and the FLIR Tools image analysis software. Surface emissivity was corrected by verifying temperature readings with a type-K contact thermocouple. Experimental relationships were established and analytical correlations derived using MATLAB and Microsoft Excel. Pilot-scale tests of six thermal stabilizers were carried out at the RUSAL Sayanogorsk production site. The results show that the breaker tip remains in the electrolyte melt for no more than 2 min. The average rate of temperature change during both heating and cooling is 45°C/min. A tip temperature below 250°C prevents raw material adhesion and improves alumina delivery. Further improvements to the breaker tip design should include the integration of a digital temperature sensor to monitor the heat-transfer medium in the thermal stabilizer and the development of an algorithm to adjust the breaker actuation cycle. To ensure industrial safety and extend the service life of the thermal stabilizer, we are currently developing a periodic inspection protocol to assess the condition of the stabilizer and the integrity of its weld seams using non-destructive testing methods. These measures ensure stable and reliable operation of the automatic alumina feeding system in prebaked-anode electrolyzers.