Sustainable Coprocessing of Biomass and Petroleum Residue in Delayed Coker Units: A Multiobjective Optimization Approach

The process parameters for copyrolysis of biomass and petroleum vacuum residue in a delayed coker are optimized. For the first time, multiobjective optimization using NSGA-II genetic algorithm and simulated annealing algorithm are deployed in conjunction with response surface methodology to obtain Pareto optimal solutions for different combinations of both yield and product property-based objectives. Biomass dosing and temperature govern Pareto fronts for maximizing coke yield and minimizing TAN. Pressure strongly influences naphtha yield, forming Pareto fronts for the maximization of LPG + naphtha yield and minimization of TAN, with a high temperature and minimal biomass dosing as optimal. Minimizing the FG yield and TAN while maximizing the naphtha + gasoil yield is favored at low biomass dosing and pressure. The opposite effect of temperature on TAN (negative) and gasoil, naphtha, and FG yields (positive) results in the formation of Pareto fronts. Biomass dosing and pressure positively affect coke and FG yields, causing the formation of Pareto fronts for maximizing the coke yield and minimizing the FG yield. The negative impact of temperature on the coke yield and coke sulfur content results in Pareto front formation for maximizing coke yield and minimizing coke sulfur. The opposing effects of temperature and pressure on calorific value versus other objectives further shape Pareto fronts for maximizing liquid yield and calorific value, while minimizing sulfur and TAN. The results offer refiners a pathway to reduce fossil carbon intensity of fuel products by coutilizing renewable biomass.