Experimental demonstration of non-linear model-based in-line control of pH

Abstract

Abstract A non-linear model-based control technique is developed and laboratory demonstrated for in-line acid neutralization using a multiple base injection approach. The controller chooses one of two simple, steady-state, three-parameter, non-linear phenomenological models which together mimic a wide range of titration curves from strong acid to highly buffered systems. The models are parameterized from on-line process data whenever nearly steady-state conditions are statistically identified. Results show excellent control performance in the presence of both ramp and step changes in acid type, acid concentration and flow rate upsets. Both industrial wastewater and mixtures prepared with acetic, phosphoric and sulphuric acids with and without common ion buffering and sodium carbonate were neutralized with sodium hydroxide in this study.