Optimal pre-flash drum pressure and optimal inlet tray for pre-flashing vapor in a crude distillation unit

The Crude Oil Distillation Unit (CDU) plays a central role in petroleum refining. Building a new CDU is very expensive, so several retrofit projects must be considered on existing CDU facilities to increase production capacity and reduce energy consumption. The application of a pre-flash drum system to CDU in recent years has had a good effect on raising the performance of CDU, especially when dealing with light crude oil. In this paper, the existing CDU has been retrofitted to raise the performance of the unit, especially when dealing with light crude oil. The retrofit is based on the implementation of a pre-flash drum and pump after the crude oil heat exchanger network and just before the furnace. In addition, the present work determines the optimal pressure of the pre-flash drum and the optimal input tray of pre-flash vapors into the CDU. The choice of optimal values depends on the minimum power consumption of the CDU and the maximum obtained products. HYSYS simulation software version 11 was used. The results showed a reduction in CDU operating cost of 7.49% at the optimal pre-flash pressure and optimal input tray for pre-flashed vapors. The presented study can be used as a guide in retrofitting existing heavy crude oil units and units under design.