Environmental and Economics Trade-Offs for the Optimal Design of a Bitumen Upgrading Plant

This work presents a novel multiobjective optimization model for bitumen upgrading operations. The proposed model considers five basic upgrading stages; which are the base of any bitumen/heavy oil upgrading operation. These stages include: primary distillation, vacuum distillation, cracking, hydrotreating, and blending. The model includes different processing units per upgrading stage. Each unit includes a set of operating modes; which are defined in terms of particular products yield and energy requirements. The proposed model takes into account two competing objective functions that must be minimized: 1) operating energy costs, and 2) associated CO₂ emissions. The optimization approach seeks for the optimal bitumen upgrading configuration by selecting the most suitable upgrading steps based on their corresponding unit's operating modes. This is done to obtain a particular type of synthetic crude oil (SCO) blend according to composition specifications. The problem was modeled as a mixed-integer nonlinear program (MINLP) using the GAMS modeling system. The model was validated using historical data of the Canadian heavy oil industry. The results show that the proposed model is a practical tool to (1) select and plan the most suitable bitumen upgrading configuration according to product specifications, (2) determine the upgrading energy costs, (3) and mitigate CO₂ emissions. (Figure Presented).