Robust decentralized PI controllers for crude unit product quality

Decentralized PI controllers are designed for a crude distillation tower. The controller design method takes into account the variations in the transfer function matrix of all three possible crude feed stocks. The performances of the proposed controllers simulated on each of the crudes are compared with those of the controller designed for a nominal crude and are also compared with those based on an average model of all the crudes. The performance of the proposed controllers is the best. The interactions are least severe. The proposed decentralized PI controllers with fixed settings are able to provide a better response for all the crude feed stocks without changing the controller settings.