CRUDE UNIT PRODUCT QUALITY-CONTROL

This paper describes the product quality controls installed on the crude unit at Cosmo Oil's Sakai Refinery during the summer of 1988. These controls were implemented using a hierarchy of regulators, including two levels of model-based controllers and one level of DCS controllers. Three series of identification step tests were conducted to assess how the unit responded while processing different crude feedstocks. Excellent levels of closed-loop performance were achieved with the model-based controllers using a single set of models, even through the nature of the crude charged to the unit was found to have a significant effect on the process models. Statistical results and closed-loop operating data illustrate this point and demonstrate the robustness of the model-based controls.