Thermodynamic analysis and techno-economic assessment of fluid catalytic cracking unit in the oil refining process

Abstract

Fluid catalytic cracking is an important, expensive, and energy-consuming unit that produces light olefins, gases, and naphtha from heavy residues. This study aims to increase light products and reduce heavy products at the FCC unit, simulated using Aspen HYSYS software. Exergoeconomic analysis using the Sankey diagram was performed for the first time for this unit, which provides the possibility of determining the important quantities in the process from a thermodynamic and thermo-economic perspective. Based on the results, the atmospheric tower consumes the most energy (about 64%) and is the most destructive unit which is responsible for 61% of exergy destruction. In terms of energy consumption, the FCC unit is ranked second with 16%. However, the FCC unit with 11% share is the third destructive unit, but an exergy efficiency of 98% was observed in this unit. A total of 267 MW of the tower's exergy was destroyed, making it the second most destructive unit in the plant. Compared to other process units, the FCC unit accounts for 9% of the total cost, while the fractionator tower is the most expensive unit in the process at 48%. The Sankey chart shows crude oil has the highest cost stream at $744,145 per hour. The FCC unit has the highest exergoeocomic factor, while the cooler has the lowest exergoeconomic factor, with 2.4 M$/h cost of exergy destruction, as well as the lowest exergy efficiency.