Characterization of Individual Anode Current Signals in Aluminum Reduction Cells

Abstract

Differing from cell voltage and line current, anode current signals can provide an insight into the localized anodic dynamic behavior in an operating Hall–Héroult reduction cell, and can be used as an alternative in-depth method to study the process in the hostile industrial potline environment. This work involves further investigations on changes in the frequency response of anode current signals (such as peaks and magnitudes) with anode age and anodic reactions. Furthermore, two process abnormalities, anode effect and anode slippage, are studied. This study demonstrates that anode current signals provide an earlier indication of an approaching anode effect than the conventional cell voltage measurements. Frequency domain analysis has been found to be an additional identifier, in separating anode effects from other abnormalities, that can also cause anode current redistribution.

Online Anode Current Signal in Aluminum Reduction Cells: Measurements and Prospects

“…16 Bearne et al examined the anode current variation with slots. 17 A similar study has also recently been conducted by Cheung et al 18 And most anode current-related studies have focused on the detection of an approaching AE. These studies suggested that the anode current signal changes in both time and frequency which makes it promising as a new logic to characterize the local cell conditions and a new monitor in industrial cells.…”

“…Some devices have been equipped with probes built into their superstructures to provide continuous ''isometric voltage drop'' measurements. [18][19][20] Since aging and installation position heavily influence the operating temperature and then the current of the rod, the measuring device also needs a K-type Teflon-coated thermocouple to monitor the change of anode rod temperature in order to compensate for temperature variation.…”

Simulation Method Based on Equivalent Circuit to Investigate the Circuit Characteristics in Aluminum Reduction Cell

“…The new anode is subsequently installed. At first, it is almost nonconductive when the new cold anode is set in the bath [16]. The anode comes to normal conductivity as the time goes.…”

“…Jeffrey T Keniry et al [5,6] confirmed that anode signal analysis offers significant potential for the improvement of cell control; James W. Evans et al [7][8][9][10] collected the individual anode current signals by sensing the magnetic fields produced by the anode current, and the signals were used to forecast anode effects (AE), unstable pots and other cell phenomena. Cheung et al [15,16] investigated the anode current signals by frequency response, and demonstrated that anode current signals provide an earlier indication of an approaching AE than the CV measurements. All of these studies prove that determining the CV and the anode current signals are the significant way to diagnose cell working conditions.…”

Testing and Characterization of Anode Current in Aluminum Reduction Cells

“…[1][2][3] Differing from the cell voltage, anode current has great significance for the early warnings of anode effects and diagnosis of localized cell conditions. [4][5][6] Although the anode current is a very important parameter in the aluminum electrolysis process, due to the difficulty of measurement and management, it is only as an auxiliary means for cell control in most of the aluminum smelters in China. At present, there are two main methods to measure the anode current.…”