A New Optimisation based Retrofit Approach for Revamping an Egyptian Crude Oil Distillation Unit

Crude oil atmospheric distillation systems are an energy intensive processes; it was evaluated that the energy requirement for such plants is equivalent to a 2% of the total crude oil processed [1]. An existing crude oil atmospheric unit is very expensive to modify due its complex configuration and interactions, and existing constraints of structure, limited space area, matches, bottlenecked equipments, etc. Thus, a few new crude distillation units are built and projects for revamping existing equipments are rather common. Revamping an existing plant is a difficult task, more complex than a new process design; many parameters must be considered and sometimes it is not possible to quantify all of them.This paper presents a new methodology based on rigorous simulation and optimisation framework that addresses both the distillation column and the heat exchanger network simultaneously to maximise the use of existing equipments. The methodology considers process changes and structural modifications together with the interactions between the existing distillation process and heat recovery system. The new method includes multiple objective functions such as energy savings, emissions reduction, capacity enhancement, and profit improvement.An actual atmospheric plant for MIDOR, an Egyptian refinery, has been considered for applications of the new optimisation methodology. Several retrofit solutions have been obtained, ranging from zero-modifications and simple additional exchanger areas to additional units or equipments.