An improved crude oil atmospheric distillation process for energy integration: Part I: Energy and exergy analyses of the process when a flash is installed in the preheating train

The purpose of this paper is to describe a specific application of energy integration improvement achieved by modifying the flowsheet of the crude oil atmospheric distillation process. It differs from other methods by the application of exergy analysis to visualize and better understand the distribution of energy degradations in the distillation column in order to find a suitable solution to reduce them. A close look at this distribution for a simple model process shows the unnecessary presence of light species throughout the whole column, whereas they could be separated before being fed to the furnace and sent directly to the upper part of the column. Since the crude oil is continuously vaporized, the installation of flashes in the preheating train ensures this separation, avoids the unnecessary overheating of the vaporized species and offers a considerable potential in reduction of fuel consumption in the furnace. However, this potential reduction is obtained under a simplification that needs to be revisited in the framework of a more realistic and more complex flowsheet. This will be done in the second part, of which this first part sets the background.