An Advanced Nonlinear Control Approach for Aluminum Reduction Process

Abstract

With the increase in amperage and associated reduction of electrolyte volume to anode surface ratio, the existing cell control method is facing more challenges due to greater variability in process conditions spatially and temporally. Therefore, it is beneficial to develop advanced control strategies that can achieve a more balanced cell with even distribution of, e.g., alumina concentration and individual anode current, and hence improve energy efficiency and reduce greenhouse gas emission. In this paper, an advanced nonlinear control approach is developed, which determines the optimal local control actions based on the measurements including the individual anode current and cell voltage. This new approach is flexible as it can optimize the control action to achieve different cell performance targets. This work illustrates the effectiveness of the proposed control with an example of improving the current efficiency. Also, different performance targets are discussed, which provide the potential for the proposed control method to have optimal control targets for best cell efficiency.