Alternative Formulations and Improvements with Valid Inequalities for the Refinery Production Scheduling Problem Involving Operational Transitions

Abstract

Operation mode switching of production units would result in long transitions with fluctuant product yields, production costs, and key product properties. To formulate the remarkable process dynamics, a mixed-integer linear programming (MILP) model involving operational transitions of mode switching was proposed for the refinery production scheduling problem in Shi et al. (Ind. Eng. Chem. Res. 2014, 53 (19), 8155−8170), which can describe transitional behaviors and provide implementable schedules. However, the model is very computationally expensive because it involves a large number of discrete and continuous variables, and the constraints about operational transitions are numerous and complex. In this paper, we study a scheduling problem similar to that in Shi et al. (Ind. Eng. Chem. Res. 2014, 53 (19), 8155−8170) and aim at improving the computational efficiency of MILP models by alternative formulations and valid inequalities. First, we redefine some sets, variables and introduce new variables to prop...