Modeling and Control of Electrodialysis Process

This study was developed and validated through industry-applied R&D in an industrial pilot plant at Arauco-Bioforest, in collaboration with AC3E, under ANID Crea y Valida funding program and FONDECYT REGULAR 1231896. This study aims to find an equivalent electrical model of a laboratory-scale electrodialysis process under pulsed voltage operation (pEDR), considering the number of ion exchange membranes in the process. Subsequently, a practical method is developed to obtain the resistance and capacitance parameters that represent it, along with a calibration method. The equivalent electrical model also incorporates the presence of fouling in the ion exchange membranes in the process, represented again by a resistance and a capacitance.Once the model is obtained, a controller is generated to minimize fouling in the ion exchange membranes by varying only the duty cycle of the pulsed voltage pEDR method (at a fixed frequency and magnitude of voltage). This is tested in a simulated environment using Simulink MATLAB. The controller employed is the Extremum Seeking Control (ESC) in cascade connection with a PI. In this way, the PI controls the average electrical current (by varying the duty cycle of the pulsed voltage pEDR) of the electrodialysis process, and then the ESC, by measuring the fouling level of the membranes, provides the PI with a new reference for average electrical current to continuously minimize fouling growth during the process operation. Finally, the controller is tested in a real electrodialysis pilot plant achieving favorable results in the reduction of fouling.