Identification and modeling of distillation columns from transient response data

Mathematical models that predict the behavior of the column are highly useful to improve the working conditions of distillation columns, i.e. increase throughput or lower energy consumption. They are a prerequisite for advanced control strategies. White-box models of distillation columns already exist, but they are often too time consuming to calibrate in real industrial cases. This paper models a binary distillation column using a black-box model in the frequency domain. One of the identification challenges of distillation columns is the long transient response that causes leakage errors in the frequency domain. This problem is solved using a recently developed local polynomial method. Furthermore, we propose a simple expedient to model the variations in the column response that are caused by the changes in ambient temperature. The results are illustrated using both simulation data of a white-box model and using real measurements.