Nonlinear model based multivariable control of a debutanizer

The debutanizer column control is a major economic incentive to a refinery owing to the importance of the product quality. The non-linear model-based multivariable control on a debutanizer has been shown to provide improved control performance of the top product and the bottom stream qualities using a steady-state process model with approximate dynamics. The control performance is much better than that achieved by the traditional PID-type control system. This chapter outlines the non-linear control method applied to an industrial debutanizer and discusses the use of inferential models to predict the iso-pentane contents in the overhead stream and the Reid vapour pressure in the bottom stream, in non-linear control applications.