Research On Modeling Of Anode Current Distribution In Aluminum Electrolytic Cell And Method For Cell Condition Diagnosis

The production of aluminum electrolysis is a complex and strong coupling dynamic process.In order to ensure the normal operation of the aluminum reduction cell,it needs to be real-time monitoring and analysis.Due to the fact that there are a lot of slot condition information in the anode current,it is an important method to detect the aluminum reduction cell malfunction by anode current.Firstly,based on the characteristics of aluminum reduction cells,in this paper,the aluminum reduction cell is equivalent to a number of anode branch circuit parallel circuit structure,each anode branch is made up of different resistive modules in series.The equivalent circuit model of the electrolytic cell is numerically solved by using the Fsolve function of MATLAB and the Levenberg Marquard optimization algorithm.Meanwhile,it eliminate the problem of the limited number of anode circuits which caused by the algebraic loop in Simulink simulation,optimize the model,and expand the number of model branches.Secondly,based on the large amount of data of the equivalent circuit model of aluminum reduction cell,this paper,by means of wavelet analysis,derives the algorithm of obtaining the fluctuation of aluminum liquid based on the anode current information.After verification,the fluctuation of liquid aluminum obtained by this algorithm is in good agreement with the initial input signal.Finally,the algorithm is extended to the case that the cell voltage can't be known accurately.The results show that the maximum error is less than 3%,which can meet the requirements of industrial analysis.Thirdly,based on the equivalent circuit model of aluminum electrolytic cell,this paper simulates the different local electrolytic cell condition by changing the bubble release,single branch polar distance condition,and makes analyses from the time domain and frequency domain respectively.Results show that changes of single branch anode bubble coverage and polar distance are reflected more obvious on the change of anode current of the branch than the cell voltage,which provides an important basis to judge the local features of the electrolytic cell;the influence of the frequency of bubble release on the change of the cell voltage and anode current is not obvious.Then,based on the simulation data generated by the model under different conditions,the algorithm for obtaining the fluctuation information of aluminum liquid is verified and improved.Finally,utilizing the spectrum analysis method,this paper analyzes the normal condition,the pole changing and the abnormal anode current based on the measured anode current data.Using the polar distance estimation model mentioned in this paper,it calculate the anode cathode distance of different electrolytic cell and different cell condition.It calculate the polar distance in normal cell condition for 3 50kA series aluminum reduction cell with 40 anode branches.In the case of the pole changing process in 400kA series aluminum reduction cell with 24 anode branches,according to the polar distance estimation result and the anode current spectrum,it is found that the fluctuation of aluminum liquid caused by pole changing has a great influence on the adjacent anode current.Then,based on the analysis of abnormal anode current data of 400kA series aluminum reduction cell,this paper diagnose the abnormal phenomenon that the anode cathode distance is too low that aluminum liquid intermittently contact the anode,resulting in anode branch instantaneous short circuit.