Inferential Control of a Distillation Column Using an Online Estimator

Abstract

The time to measure and maintain distillate quality in the presence of disturbances is the main objective of the distillation process. To maintain the product quality, a suitable tray temperature is kept constant with the help of a control strategy near its set point. As the controlled variables cannot be measured online easily due to measurement lags and sampling delays, the secondary measurement techniques are used to estimate the distillate quality by adjusting the values of manipulated variables (inferential control). This paper presents an inferential control scheme for a distillation column using an Ethernet-based data acquisition system to provide a standard online estimator. In the present scheme the distillation parameters are acquired from a client PC connected to the network and the distillate composition is estimated online by a developed ANN-based estimator. The above estimator is used for an inferential control strategy to control distillate composition. The inferential control scheme is exercised for various disturbances and the effect of the disturbances is observed on distillate quality.