Modeling, control, and optimization of crude distillation units

Abstract

The crude distillation unit performs the initial distillation of the crude oil into several boiling range fractions, and it is one of the most energy consuming and complex distillation columns in a refinery. The operational objectives are to maximize the yields of on specification distillates, increase crude capacity, reduce fuel consumption, maximize the heat recovery, stabilize the column operation, and enhance the operators`` tasks. A mathematical model for the rigorous steady-state simulation of a crude tower is presented and also the efficient algorithms are discussed. In order to solve the control problems when decentralized control scheme is used, we apply multivariable control scheme that is QDMC(Quadratic Dynamic Matrix Control). Here we also discuss off-line optimization studies under changing market environments - several sets ocost scenarios. Finally, we present a straightforward method of on-line optimization through the integration of the following capabilities - modeling, simulation, advanced process control, optimization, data reconciliation, model update, and dynamic enforcement. If this system is installed in a real plant, it can be translated into savings or increased earnings worth up to several million dollars per year.