Study And Application On The Online Monitoring System Of Anode-cathode Distance(ACD) And Aluminium Waves In Aluminium Electrolysis Cell

At present, the problem of aluminium wave and asymmetrical ACD(anode-cathode distance) become more and more serious along with the increase of cells' capacity. Therefore, it becomes more and more important, which can provide some basis for energy saving in aluminium industry.The study in this dissertation was performed on CHLCO. An instrument and its software (which is applying as a patent) were researched and developed to measure molten metal waves. So molten metal waves can be measured continually. The relationship among vertical local oscillations of molten metal, anodic current and anode-cathode distance was found by means of measure and analysis. The corresponding relationship between equal-distant voltage-drop and aluminium wave was found, and anode-bubble has little influence on anode current.As a great deal of experiment, five pantmeters including anodic equal-distant voltage drops, Anodic resistance, temperature of anodic leader, cell voltage and the percentage of vertical current and anodic current become assistant variables of the oft-measure model. Because the variables are non-linear and correlative, Soft-measure model based on FCM and Multiple Neural Network was set up by Fuzzy Logic Toolbox and Neural Network Toolbox of Matlab6.5. The relationship among Anodic resistance & temperature of anodic leader and numbers of days was expressed by formula. Current distributing of anodic bottom was researched. Because of simulation, the author indicate that the current which don't come through anodic bottom account for 18.7% of the anodic leader current. Then appropriate hardware was chosen to the system, and software of the system was developed with Delphi7.0. Anode-cathode distance(ACD) and three-dimensional of aluminium waves could be visualization online, and it could provide information to operational optimization to cells.The system was running for optimizing operation, and some representative cases was analysed. A thought make ACD equality which based on the system and its implement ways were developed. So, the cells can steadily work in low ACD and keep magnetohydrodynamic (MHD) steady and high current efficiency.The system was steady-going in Guangxi Filiale 320kA cell of CHLCO. During the experiment, cell voltage reduced to 4.17V, at the same time the cell was well-balanced. In the conclusion, electrical consumption went down 127kWh/t.