Theory and Application of the Lang-Gilles Observer for Distillation Processes

This thesis deals with the nonlinear full state observer for distillation processes first introduced by Lang and Gilles in 1990. The observer is very attractive in practice as it requires only few temperature measurements in each section of a distillation column and only few observer parameters need to be tuned. We provide conditions under which this observer converges and derive a simple rule for the tuning of the observer parameters. We also give a method for the on-line estimation of the Murphree tray efficiency. Such on-line methods are rarely found in ­literature. In a sequence of simulation studies, we investigate the capabilities of the observer for the estimation of the tray efficiency and for model-predictive control. The simulation studies are based on distillation processes for separation of multicomponent mixtures and one of the studies introduces a plant-model mismatch. ...