(165a) Revamp of Heat-Integrated Crude Oil Distillation Systems for Energy Reduction and New Product Demands

Heat-integrated crude oil distillation systems (i.e. the preheat train and crude oil distillation columns) are complex, energy intensive and expensive to modify. Strong interactions exist between the distillation system and the preheat train. Therefore, many degrees of freedom and many constraints need to be taken into account during process revamps.

An optimisation-based design methodology is proposed for the retrofit design and analysis of heat-integrated crude oil distillation systems. The approach considers the distillation column and preheat train in a single framework and aims to improve the overall performance of the system. In the approach, distillation units are simulated using simplified models that allow the specification of the products and the heat exchanger network is studied in terms of its detailed structure. The hydraulic constraints of the existing distillation column design are accounted for, and the existing numbers of stages in each section are considered. Moreover, exiting product qualities are constrained within acceptable range. Simulated Annealing has been employed as the optimisation algorithm because of its ability to optimise both structural and operational process variables. The number of structural modifications to the existing system can also be controlled to allow practical and simple retrofit solutions to be obtained.

Case studies are presented addressing the reduction of energy consumption in an existing heat-integrated atmospheric distillation column, and for improving profit by adjusting product yields according to market value.