Simultaneous optimization of crude oil refinery vacuum distillation column and corresponding ejector system

Abstract

A vacuum distillation unit (VDU) is a relatively complex crude oil refining process that usually overlooked in researches. A detailed review of the corresponding literature reveals that most of the limited existing researches focus on either the study of the vacuum tower alone or its vacuum creating ejector system. For the first time, the combination of VDU tower and corresponding ejectors are studied in this article by resorting to coupling of Aspen-HYSYS simulation software with Ansys-FLUENT computational fluid dynamic. Both simulations were initially validated by using two sets of experimental and industrial data, borrowed from literature.Optimization of an industrial unit improved its process economics by boosting the heavy vacuum gasoil production around 38% and reducing the less valuable cut of vacuum residue by 28%, which increases the overall earnings of the optimal VDU column economics over 140 MM$/year. Furthermore, sensitivity analysis of the VDU ejector system revealed that the primary steam cost does not depend on the corresponding temperature, while, it rapidly rises, when the motive fluid pressure increases. The overall simulation results of the VDU tower and corresponding ejector system concluded that the lower primary steam pressures are more favorable both from operational and economical standpoints.