Controle de pH no tratamento de efluente de unidade desmineralizadora em uma indústria petroquímica

Abstract

This work aims to automate the regulation of the pH neutralization process of the effluent generated by the Demineralizing Unit in a specific Petrochemical Industry. The pH of the effluent can undergo rapid changes to acidic or basic values as it approaches the point of neutrality, due to its logarithmic curve. Currently, regulation is carried out manually by the field operator, resulting in a significant waste of inputs used to ensure compliance with process specifications. To achieve this goal, samples of the real system were taken, which allowed the creation of a mathematical model to analyze the system’s behavior and characteristics. The NARX (Nonlinear Auto Regressive with external input) non-linear model structures were used to describe the behavioral dynamics of the effluent pH in relation to the dosage of sulfuric acid. Based on this mathematical model, we proposed regulating the system using a classic PI-type control strategy, using a linearization condition at the pH equilibrium point, as well as analyzing the system’s closed-loop performance.