Operational optimization of co-processing of heavy oil and bio-oil based on the coordination of desulfurization and deoxygenation

Abstract

Co-processing of heavy oil and bio-oil in an existing refinery has been proposed to reduce the production cost of bio-fuels by using the existing refinery infrastructures. Considering the high sulfur content in heavy oil and high oxygen content in bio-oil, an operational optimization model integrated impurity distributions of fluid catalytic cracker (FCC) and hydrogenation reaction kinetics of hydrotreating (HDT) unit is built to lower the utility cost of co-processing process based on coordination of desulfurization and deoxygenation. Polynomial fitting is adopted to reduce the non-linearity of kinetics and a solving strategy is proposed to guarantee the accuracy. Results indicate that the total utility cost of the co-processing process reduces by 6.7% by optimizing impurity removal degrees of all units in the co-processing process. The impurity removal of FCC should not be ignored as it can reduce more than 28% impurity of the total impurity from feed oil without consuming hydrogen gas. The advantages of integrating FCC impurity distributions and hydrogenation reaction kinetics into the proposed model are also discussed. It is necessary to integrate FCC and kinetics when optimizing the co-processing process or FCC and HDT units in refinery.